Cogprints: No conditions. Results ordered -Date, Title. 2018-01-17T14:26:09ZEPrintshttp://cogprints.org/images/sitelogo.gifhttp://cogprints.org/2014-08-24T21:07:30Z2015-04-20T11:40:47Zhttp://cogprints.org/id/eprint/9756This item is in the repository with the URL: http://cogprints.org/id/eprint/97562014-08-24T21:07:30ZCo-Variations among Cognition, Cerebellar
Disorders and Cortical Areas With
Regional Glucose-Metabolic Activities in a
Homogeneous Sample with Uner Tan Syndrome:
Holistic Functioning of the Human BrainPatients with Uner Tan syndrome (UTS) exhibit habitual quadrupedal locomotion (QL), intellectual disability, dysarthric speech and truncal ataxia. Examination of cognitive ability in this syndrome has not yet been demonstrated in the scientific literature. Aims: (i) To analyze the cognitive abilities of the siblings with UTS; (ii) to assess the grade of their ataxia in relation to cerebellar disorders; (iii) to measure the metabolic activities of various cerebral regions in comparison with healthy individuals; (iv) to detect the interrelationships among all of the measured variables (IQ test scores, ataxia scores, cerebro-cerebellar areas and their metabolic activity levels) to reveal the holistic activity of the
brain. The Minimental State Examination (MMSE) and Wechsler Adult Intelligence Scale (WAIS-R) were applied to the affected cases and healthy subjects. Cerebellar disorders were assessed by the International Cooperative Ataxia Rating Scale (ICARS). Brain MRI scans were performed and cerebro-cerebellar areas were measured on MRI scans, including their metabolic activities (SUV), measured by positron emission tomography (PET) scanning. MMSE and WAIS-R scores both correlated with cerebro-cerebellar areas. Cerebello-vermial areas and their metabolic activities were significantly smaller in patients than in normal controls; areas of the remaining structures were not significantly different between patients and healthy subjects. Brain areas significantly inter-correlated: ICARS negatively correlated with WAIS-R,MMSE scores, SUV, and cerebro-cerebellar areas, which significantly correlated with each other. The results suggested (i) ICARS may not only be a test for cerebellar disorders, but also may be related to global functioning of all of the
cerebro-cerebellar regions; (ii) ICARS, WAIS-R and MMSE may be measures of emergent properties of the holistic
activity of the brain; (iii) the psychomotor disorders in UTS may be related to decreased brain metabolism.Prof. Dr. Uner Tanunertan37@yahoo.com2014-05-10T00:39:06Z2015-04-20T11:45:42Zhttp://cogprints.org/id/eprint/9686This item is in the repository with the URL: http://cogprints.org/id/eprint/96862014-05-10T00:39:06ZTwo families with quadrupedalism, mental retardation, no
speech, and infantile hypotonia (Uner Tan Syndrome
Type-II); a novel theory for the evolutionary emergence of
human bipedalismTwo consanguineous families with Uner Tan Syndrome (UTS) were analyzed in relation to self-organizing processes in complex systems, and the evolutionary emergence of human
bipedalism. The cases had the key symptoms of previously reported cases of UTS, such as quadrupedalism, mental retardation, and dysarthric or no speech, but the new cases
also exhibited infantile hypotonia and are designated UTS Type-II. There were 10 siblings in Branch I and 12 siblings in Branch II. Of these, there were seven cases exhibiting habitual quadrupedal locomotion (QL): four deceased and three living. The infantile hypotonia in the
surviving cases gradually disappeared over a period of years, so that they could sit by about 10 years, crawl on hands and knees by about 12 years. They began walking on all fours at around 14 years, habitually using QL. Neurological examinations showed normal tonus in
their arms and legs, no Babinski sign, brisk tendon reflexes especially in the legs, and mild tremor. The patients could not walk in a straight line, but (except in one case) could stand up and maintain upright posture with truncal ataxia. Cerebello-vermial hypoplasia and mild gyral simplification were noted in their MRIs. The results of the genetic analysis were inconclusive: no genetic code could be identified as the triggering factor for the syndrome
in these families. Instead, the extremely low socio-economic status of the patients was thought to play a role in the emergence of UTS, possibly by epigenetically changing the brain structure and function, with a consequent selection of ancestral neural networks for
QL during locomotor development. It was suggested that UTS may be regarded as one of the unpredictable outcomes of self-organization within a complex system. It was also
noted that the prominent feature of this syndrome, the diagonal-sequence habitual QL, generated an interference between ipsilateral hands and feet, as innon-humanprimates. It was suggested that this may have been the triggering factor for the attractor state “bipedal locomotion” (BL), which had visual and manual benefits for our ape-like ancestors, and therefore enhancing their chances for survival, with consequent developments in the psychomotor domain of humans. This was put forward as a novel theory of the evolution of BL in human beings.Prof. Dr. Uner Tan2013-09-17T14:26:28Z2013-09-17T14:26:28Zhttp://cogprints.org/id/eprint/8982This item is in the repository with the URL: http://cogprints.org/id/eprint/89822013-09-17T14:26:28ZHuman quadrupedalism is not an epiphenomenon caused
by neurodevelopmental malformation and ataxiaTwo cases with quadrupedal locomotion (QL) were presented. In both cases, cognitive and psychiatric functions were normal and, no neurological deficits were observed, except for a sequel paralysis of left leg in Case 2. It was suggested that human QL (1) should not be considered as an epiphenomenon caused by neurodevelopmental malformation and
ataxia, but (2) may be considered as a re-emergence of the ancestral diagonal QL, and (3) it may spontaneously emerge in humans with entirely normal brains, by taking advantage
of neural networks such as central pattern generators that have been preserved for about 400 million years.Prof. Dr. Uner Tanunertan37@yahoo.com2013-05-04T23:25:03Z2013-05-04T23:25:03Zhttp://cogprints.org/id/eprint/8968This item is in the repository with the URL: http://cogprints.org/id/eprint/89682013-05-04T23:25:03ZDevelopment of bipedal and quadrupedal locomotion in humans from a dynamical systems perspective The first phase in the development 0f locomotion, pr,öary variability would occur in normal fetuses and infants, and those with Uner Tan syndrome. The neural networks for quadrupedal locomotion have apparently been transmitted epigenetically through many species since about 400 MYA.
The second phase is the neuronal selection process. During infancy, the most effective motor pattern(s) and their associated neuronal group(s) are selected through experience.
The third phase, secondary or adaptive variability, starts to bloom at two to three years of age and matures in adolescence. This third phase may last much longer in some patients with Uner Tan syndrome, with a considerably delay in selection of the well-balanced quadrupedal locomotion, which may emerge very late in adolescence in these cases. Prof. Dr. Uner Tanunertan37@yahoo.com2013-05-04T23:24:57Z2013-05-04T23:24:57Zhttp://cogprints.org/id/eprint/8967This item is in the repository with the URL: http://cogprints.org/id/eprint/89672013-05-04T23:24:57ZÜner Tan Syndrome: Review and Emergence of Human Quadrupedalism in Self-Organization,
Attractors and Evolutionary Perspectives
The first man reported in the world literature exhibiting habitual quadrupedal locomotion was discovered by a British traveler and writer on the famous Baghdat road near Havsa/Samsun on the middle Black-Sea coast of Turkey (Childs, 1917). Interestingly, no single case with human quadrupedalism was reported in the scientific literature after Child's first description in 1917 until the first report on the Uner Tan syndrome (UTS: quadrupedalism, mental retardation, and impaired speech or no speech)in 2005 (Tan, 2005, 2006). Between 2005 and 2010, 10 families exhibiting the syndrome were discovered in Turkey with 33 cases: 14 women (42.4%) and 19 men (57.6%). Including a few cases from other countries, there were 25 men (64.1%)and 14 women (35.9%). The number of men significantly exceeded the number of women (p < .05). Genetics alone did not seem to be informative for the origins of many syndromes, including the Uner Tan syndrome. From the viewpoint of dynamical systems theory, there may not be a single factor including the neural and/or genetic codes that predetermines the emergence of the human quadrupedalism.Rather, it may involve a self-organization process, consisting of many decentralized and local interactions among neuronal, genetic, and environmental subsystems. The most remarkable characteristic of the UTS, the diagonal-sequence quadrupedalism is well developed in primates. The evolutionarily advantage of this gait is not known. However, there seems to be an evolutionarily advantage of this type of locomotion for primate evolution, with regard to the emergence of complex neural circuits with related highly complex structures. Namely, only primates with diagonal-sequence quadrupedal locomotion followed an evolution favoring larger brains, highly developed cognitive abilities with hand skills, and language, with erect posture and bipedal locomotion, creating the unity of human being. It was suggested that UTS may be considered a further example for Darwinian diseases, which may be associated with an evolutionary understanding of the disorders using evolutionary principles, such as the natural selection. On the other hand, the human quadrupedalism was proposed to be a phenotypic example of evolution of reverse, i.e., the reacquisition by derived populations of the same character states as those of ancestor populations. It was also suggested that the emergence of the human quadrupedalism may be related to self-organizing processes occurring in complex systems, which select or attract one preferred behavioral state or locomotor trait out of many possible attractor states. Concerning the locomotor patterns, the dynamical systems in brain and body of the developing child may prefer some kind of locomotion, according to interactions of the internal components and the environmental conditions, without a direct role of any causative factor(s), such as genetic or neural codes, consistent with the concept of self-organization, suggesting no single element may have a causal priority. Prof. Dr. Uner Tanunertan37@yahoo.comProf. Dr. Yusuf TamamDr. Sibel Karacasibelemre2003@yahoo.comProf. Dr. Meliha TanMeliha_Tan@yahoo.com2017-02-18T20:23:42Z2017-02-18T20:23:42Zhttp://cogprints.org/id/eprint/9649This item is in the repository with the URL: http://cogprints.org/id/eprint/96492017-02-18T20:23:42ZUner Tan Syndrome: Review and Emergence of Human Quadrupedalism in Self-Organization, Attarctors and evolutionary PerspectivesUner Tan syndrome, discovered in 2005 by Dr. Tan, in Southern Turkey, mainly consists of habitual quadrupedal locomotioni impaired intelligence, and dysarthric or no speech, with or without (rarely) cerebello-vermial hypoplasia and mildly simplified cortical gyri.
This syndrome may be considered wthin the framework of the nonprogressive autosomal recessive cerebellar ataxias, associated with various genetic mutations (genetic heterogeneity). This is a unique condition among disequilibrium syndrome, Cayman ataxia, and Joubert syndrome.
From the viewpoint of dynamical systems theory, there may be not a single factor including a ganetic code that predetermines the emergence of human quıadrupedalism, seen for instance in Uner Tan syndrome. Rather it may involve self-organization process, consisting of many decentralized and local interactions among neuronal, genetic, and environmental subsystems. Prof. Dr. Uner Tanunertan37@yahoo.comProf. Dr. Yusuf TamamProf. Dr. Sibel KaracaProf. Dr. Meliha TanMeliha_Tan@yahoo.com2010-10-18T11:04:33Z2011-03-11T08:57:45Zhttp://cogprints.org/id/eprint/7035This item is in the repository with the URL: http://cogprints.org/id/eprint/70352010-10-18T11:04:33ZTwo New Cases of Uner Tan Syndrome: One Man
with Transition from Quadrupedalism to Bipedalism;
One Man with Consistent QuadrupedalismBackground: Uner Tan syndrome, first described in
2005, consists of three main symptoms: habitual
locomotion on all four extremities, impaired
intelligence, and dysarthric or no speech. This
extremely rare syndrome shows an autosomal
recessive inheritance due to consanguineous
marriages between parents. In general, there is a
cerebellovermial hypoplasia with a mild gyral
simplification in the cerebral cortex. Truncal ataxia is
the main neurological finding, causing difficulty in
standing and upright walking on two legs.
Methods: As soon as the new cases came to light, the
family was visited. After taking the basic information
about the family members, the traditional neurological
examinations were performed, MRI scans of the
patients and of a healthy family member were taken in
a hospital nearest to the residence (a small village
near Kars, Turkey). The patients were also filmed to
analyze their walking patterns.
Results: Two individuals (case 1, 44y; case 2, 43y)
among six siblings from a family with consanguineous
parents exhibited Uner Tan syndrome, with
quadrupedalism, impaired intelligence, and dysarthric
speech. Their pedigree suggested an autosomal
recessive inheritance. MRI scans showed inferior
cerebellovermial and pontobulbar hypoplasia.
Case 1 did not display hypotonia, while case 2 had
been hypotonic for two years after birth. Case 2’s
hypotonia progressively disappeared, and at three
years old he started to sit, and could walk on all fours
by the age of four. Case 1 was quadrupedal for 20
years, and then walked upright with the aid of a
walking stick. Tendon reflexes were normal in case 1
but hyperactive in the lower extremities of case 2;
Babinsky was absent in case 1 but bilaterally present
in case 2. There was no nystagmus, no strabismus,
and no pes pedus in either case. Cognition was
severely impaired in both.
Conclusion: The emergence of quadrupedalism
during development, with a transition into bipedalism
in case 1, and the emergence of the quadrupedalism
after a full hypotonia and no locomotion in case 2,
were considered as examples of the processes of
adaptive self-organization, from the viewpoint of
dynamic systems theory.Prof. Dr. Uner Tanunertan37@yahoo.com2010-09-13T03:59:01Z2011-03-11T08:57:40Zhttp://cogprints.org/id/eprint/6939This item is in the repository with the URL: http://cogprints.org/id/eprint/69392010-09-13T03:59:01ZUner Tan Syndrome: History, Clinical Evaluations, Genetics, and the
Dynamics of Human QuadrupedalismAbstract: This review includes for the first time a dynamical systems analysis of human quadrupedalism in Uner Tan syndrome, which is characterized by habitual quadrupedalism, impaired intelligence, and rudimentary speech. The first family was discovered in a small village near Iskenderun, and families were later found in Adana and two other small villages near Gaziantep and Canakkale. In all the affected individuals dynamic balance was impaired during upright walking,and they habitually preferred walking on all four extremities. MRI scans showed inferior cerebellovermian hypoplasia with slightly simplified cerebral gyri in three of the families, but appeared normal in the fourth. PET scans showed a decreased glucose metabolic activity in the cerebellum, vermis and, to a lesser extent the cerebral cortex, except for one patient,
whose MRI scan also appeared to be normal. All four families had consanguineous marriages in their pedigrees,
suggesting autosomal recessive transmission. The syndrome was genetically heterogeneous. Since the initial discoveries
more cases have been found, and these exhibit facultative quadrupedal locomotion, and in one case, late childhood onset. It has been suggested that the human quadrupedalism may, at least, be a phenotypic example of reverse evolution. From the viewpoint of dynamic systems theory, it was concluded there may not be a single factor that predetermines human quadrupedalism in Uner Tan syndrome, but that it may involve self-organization, brain plasticity, and rewiring, from the many decentralized and local interactions among neuronal, genetic, and environmental subsystems.Prof. Dr. Uner Tanunertan37@yahoo.com2008-09-19T13:56:57Z2011-03-11T08:57:12Zhttp://cogprints.org/id/eprint/6209This item is in the repository with the URL: http://cogprints.org/id/eprint/62092008-09-19T13:56:57ZResponse probability and latency: a straight line, an operational definition of meaning and the structure of short term memoryThe functional relationship between response probability and time is investigated in data from Rubin, Hinton and Wenzel (1999) and Anderson (1981). Recall/recognition probabilities and search times are linearly related through stimulus presentation lags from 6 seconds to 600 seconds in the former experiment and for repeated learning of words in the latter. The slope of the response time vs. probability function is related to the meaningfulness of the items used. The Rubin et al data suggest that only one memory structure is present or that all memory structures probed show the same linear relation of response probability and time. Both sets of data also suggest that the memory items, presumably in the neocortex, have a finite effective size that shrinks in a logarithmic fashion as the time since stimulus presentation increases or the overlearning decreases, away from the start of the search. According to the logarithmic decay, the size of the memory items decreases to a couple of neurons at about 1500 seconds for recall and 1100 seconds for recognition – this could be the time scale for a short term memory being converted to a long term memory. The incorrect recall time saturates in the Rubin et al data (it is not linear throughout the experiments), suggesting a limited size of the short term memory structure: the time to search through the structure for recall is 1.7 seconds. For recognition the corresponding time is about 0.4 seconds, to compare with the 0.243 seconds given by the data analysis of Cavanagh of Sternberg-like experiments (1972). Dr. Eugen Tarnow2007-12-10T21:45:54Z2011-03-11T08:57:01Zhttp://cogprints.org/id/eprint/5858This item is in the repository with the URL: http://cogprints.org/id/eprint/58582007-12-10T21:45:54ZUNERTAN SYNDROME: A CASE SERIES DEMONSTRATING HUMAN DEVOLUTIONA large family with six individuals exhibiting the Unertan syndrome (UTS)was identified residing in southern Turkey. All of the individuals had mental impairments and walked on all four extremities. The practice of intra-familial
marriages suggested that theUTS may be an autosomal recessive disorder, similar to previously described cases. The inferior portions of the cerebellum and vermis were
absent as evidenced by MRI and CT scans. The height and head circumference of those affected were within normal ranges. Barany’s test suggested normal vestibular
system function. The subjects could not name objects or their close relatives. The males (n = 4) could understand simple questions and commands, but answered questions with only one or two sounds. The females (n = 2) were superior to
the males with respect to language skills and walking, suggesting an association between walking and speaking abilities. One male exhibited three walking patterns
at the same time: quadripedal, tiptoe, and scissor walking. Another male used two walking styles: quadripedal and toe-walking. It is emphasized that there are important differences between the UTS and the disequilibrium syndrome. It is suggested that the inability to walk upright in those affected with the UTS may be
best explained by a disturbance in lateral-balance mechanisms,without being related to the cerebello-vestibular system.An interruption of locomotor development during the transition from quadripedality to bipedality may result in habitual walking on all four extremities and is normal in some children. Because quadripedal
gait is an ancestral trait, individuals with the UTS, exhibiting a manifestation of reverse evolution in humans, may be considered an experiment of nature, useful
in understanding the mechanisms underlying the transition from quadripedality to bipedality during human evolution. The proposed mutant gene or gene pool playing
a role in human quadrupedality may also be responsible for human bipedality at the same time. Herein there is no intent to insult or injure; rather, this report is an
endeavor to better understand human beings. Supplementary materials are available for this article. Go to the publisher’s online edition of International Journal of
Neuroscience for the following free supplemental resource(s): video clips.Prof. Dr. Uner Tanunertan37@yahoo.comDr. Sibel Karacasibelemre2003@yahoo.comDr. Meliha TanMeliha_Tan@yahoo.com2007-11-22T01:49:16Z2011-03-11T08:57:00Zhttp://cogprints.org/id/eprint/5832This item is in the repository with the URL: http://cogprints.org/id/eprint/58322007-11-22T01:49:16ZCyclooxygenase Inhibition Limits Blood-Brain Barrier Disruption following Intracerebral Injection of Tumor Necrosis Factor-alpha in the RatIncreased permeability of the blood-brain barrier (BBB) is important in neurological disorders. Neuroinflammation is associated with increased BBB breakdown and brain injury. Tumor necrosis factor-alpha (TNF-a) is involved in BBB injury and edema formation through a mechanism involving matrix metalloproteinase (MMP) upregulation. There is emerging evidence indicating that cyclooxygenase (COX) inhibition limits BBB disruption following ischemic stroke and bacterial meningitis, but the mechanisms involved are not known. We used intracerebral injection of TNF-a to study the effect of COX inhibition on TNF-a-induced BBB breakdown, MMP expression/activity and oxidative stress. BBB disruption was evaluated by the uptake of 14C-sucrose into the brain and by magnetic resonance imaging (MRI) utilizing Gd-DTPA as a paramagnetic contrast agent. Using selective inhibitors of each COX isoform, we found that COX-1 activity is more important than COX-2 in BBB opening. TNF-a induced a significant upregulation of gelatinase B (MMP-9), stromelysin-1 (MMP-3) and COX-2. In addition, TNF-a significantly depleted glutathione as compared to saline. Indomethacin (10 mg/kg; i.p.), an inhibitor of COX-1 and COX-2, reduced BBB damage at 24 h. Indomethacin significantly attenuated MMP-9 and MMP-3 expression and activation, and prevented the loss of endogenous radical scavenging capacity following intracerebral injection of TNF-a. Our results show for the first time that BBB disruption during neuroinflammation can be significantly reduced by administration of COX inhibitors. Modulation of COX in brain injury by COX inhibitors or agents modulating prostaglandin E2 formation/signaling may be useful in clinical settings associated with BBB disruption.Dr. Eduardo Candelario-Jalilecandelario-jalil@salud.unm.eduDr. Saeid TaheriDr. Yi YangDr. Rohit SoodDr. Mark GrosseteteEduardo EstradaDr. Bernd L. FiebichDr. Gary A. Rosenberg2007-10-22T10:43:08Z2011-03-11T08:56:59Zhttp://cogprints.org/id/eprint/5775This item is in the repository with the URL: http://cogprints.org/id/eprint/57752007-10-22T10:43:08ZUNERTAN SYNDROME: REVIEW AND REPORT OF FOUR NEW CASESThe aim of this study was to describe additional patients (n = 3) exhibiting the Unertan syndrome (UTS), resident in rural areas of Canakkale. The 8th and 9th families with the UTS, with a total of 16 members affected, have not been previously characterized. A single, non-familial case (Bayramic, Canakkale) occurred during early childhood after an infection with a high fever. Three cases of familial UTS were located in another village in Canakkale. All cases exhibited the three key symptoms of the UTS: 1) walking on all four extremities, 2) primitive language (only sounds), and 3) rudimentary intelligence. Magnetic resonance imaging showed mild vermial hypoplasia in the non-familial case, while there was cerebellar and vermial hypoplasia with a flattened cerebral cortex in the familial cases. Dexterity of the fingers was normal. The man from the latter family was fond of dragging a wooden box after fastening a string around his belt. The collective observations and clinical findings suggest two etiologies for the UTS: 1) genetic, via autosomal recessive transmission and 2) viral, likely the poliovirus affecting the cerebro-cerebellar structures. At a minimum, vermial hypoplasia is suggested to cause fully developed UTS. The subjects could stand upright and even walk bipedally, despite difficulties in balance (ataxia), but they preferred quadrupedal walking. The main difficulty with gait was maintaining a dynamic-asymmetric lateral balance and initiation of the first step during standing. Apparently, a quadrupedal gait in an adult is a developmental regression with absence of the higher control mechanisms for asymmetric lateral balance during bipedal walking. It is suggested that these individuals exhibit ancestral traits; the quadrupedal gait with rudimentary intelligence and primitive speech resulting from viral infections and/or genetic damage may cause devolution (reverse evolution), a manifestation of an experiment of nature as well as experimental studies in animal models. The results support the notion of punctuated evolution, in contrast to Darwin`s theory of graded evolution. Dragging a wooden box using a string wrapped around the belt may also be an example of reverse evolution with regard to tool making, illuminating the very long-lasting period before the invention of the wheel. Herein, there has been no intent to insult or injure these individuals affected by the UTS, rather this is an endeavor to better understand the mystery of human evolution. Prof. Dr. Uner Tanunertan37@yahoo.com2006-10-05Z2011-03-11T08:56:35Zhttp://cogprints.org/id/eprint/5125This item is in the repository with the URL: http://cogprints.org/id/eprint/51252006-10-05ZThe primary function of REM sleepIn this paper, the physiological features associated with the different stages of REM sleep and with what information processing researchers have called “effort” and “arousal” are compared. It is suggested that tonic REM sleep and effort involve an increase in the metabolism of cerebral glycogen, and phasic REM sleep and arousal involve the transfer of glucose from the body to the brain. Both stages of REM sleep seem to elevate cerebral glucose levels and likely result in increased ATP generation in some part(s) of the brain. It is noted that the functioning of the hippocampus depends heavily on ATP, and that this part of the brain becomes especially active during REM sleep. From this, although many details remain to be clarified, it seems clear that the primary function of REM sleep is to re-energize the brain.Mr. Andrew E. Bernhard2009-03-04T03:27:09Z2011-03-11T08:57:19Zhttp://cogprints.org/id/eprint/6362This item is in the repository with the URL: http://cogprints.org/id/eprint/63622009-03-04T03:27:09Z“UNER TAN SYNDROME” IN TWO TURKISH FAMILIES IN RELATION TO DEVOLUTION AND EMERGENCE OF HOMO ERECTUS: NEUROLOGICAL EXAMINATION, MRI AND PET SCANS“Uner Tan Syndrome” consists of two main symptoms: quadrupedal gait and primitive cognitive abilities including language and conscious experience. To assess the central mechanisms involved in this syndrome, we performed MRI and PET scans on affected and unaffected individuals from both families. All affected individuals were also subjected to neurological examination. To assess the integrity of the peripheral and central vestibular system, Barany’s caloric test was applied to the affected individuals. Brain MRI and PET scans were performed on normal subjects (N = 7) and patients (N = 7). Right- and left-cerebral and cerebellar areas, including the vermial and callosal areas, were measured on the MRI scans using a computer cursor. Quadrupedal gait, mental retardation, dysartric speech, nystagmus, severe truncal ataxia, hyperreflexia, astasia and abasia were observed in the affected individuals from both families. Cerebellum and vermis were atrophic in the MRI and PET scans of the first family. In contrast, the brain MRI seemed to be normal in the MRI and PET scans of affected individuals from the second family. The caloric test revealed central vestibular damage in patients from the first family and peripheral vestibular damage in patients from the second family. The results suggest that “Uner Tan Syndrome”, discovered in two unrelated families, may be caused by peripheral or central vestibular damage resulting from different genetic defects. Cerebellar hypoplasia may not be a prerequisite for the emergence of this syndrome. Primitive mental abilities may be explained by damage within the vestibulo-cerebellar system, while the quadrupedal gait may be due to a genetic defect within the higher brain centers that suppress the atavistic brain networks controlling quadrupedal gait and helped in the emergence of the habitual bipedal gait during human evolution. This retarded development of human locomotion –devolution- may illuminate the brain mechanisms responsible for the transition from quadrupedality to bipedality in human evolution.Prof. Dr. Üner TANDr. Sadrettin PENÇEDr. Mustafa YILMAZDr. Ayhan ÖZKURDr. Sibel KARACADr. Meliha TANDr. Mehmet KARATAŞ2007-02-19Z2011-03-11T08:56:46Zhttp://cogprints.org/id/eprint/5387This item is in the repository with the URL: http://cogprints.org/id/eprint/53872007-02-19Z“UNER TAN SYNDROME” IN TWO TURKISH FAMILIES IN RELATION TO DEVOLUTION AND EMERGENCE OF HOMO ERECTUS: NEUROLOGICAL EXAMINATION, MRI AND PET SCANS“Uner Tan Syndrome” consists of two main symptoms: quadrupedal gait and primitive cognitive abilities including language and conscious experience. To assess the central mechanisms involved in this syndrome, we performed MRI and PET scans on affected and unaffected individuals from both families. All affected individuals were also subjected to neurological examination. To assess the integrity of the peripheral and central vestibular system, Barany’s caloric test was applied to the affected individuals. Brain MRI and PET scans were performed on normal subjects (N = 7) and patients (N = 7). Right- and left-cerebral and cerebellar areas, including the vermial and callosal areas, were measured on the MRI scans using a computer cursor. Quadrupedal gait, mental retardation, dysartric speech, nystagmus, severe truncal ataxia, hyperreflexia, astasia and abasia were observed in the affected individuals from both families. Cerebellum and vermis were atrophic in the MRI and PET scans of the first family. In contrast, the brain MRI seemed to be normal in the MRI and PET scans of affected individuals from the second family. The caloric test revealed central vestibular damage in patients from the first family and peripheral vestibular damage in patients from the second family. The results suggest that “Uner Tan Syndrome”, discovered in two unrelated families, may be caused by peripheral or central vestibular damage resulting from different genetic defects. Cerebellar hypoplasia may not be a prerequisite for the emergence of this syndrome. Primitive mental abilities may be explained by damage within the vestibulo-cerebellar system, while the quadrupedal gait may be due to a genetic defect within the higher brain centers that suppress the atavistic brain networks controlling quadrupedal gait and helped in the emergence of the habitual bipedal gait during human evolution. This retarded development of human locomotion –devolution- may illuminate the brain mechanisms responsible for the transition from quadrupedality to bipedality in human evolution.Prof. Dr. Üner TANDr. Sadrettin PENÇEDr. Mustafa YILMAZDr. Ayhan ÖZKURDr. Sibel KARACADr. Meliha TANDr. Mehmet KARATAŞ2005-05-02Z2011-03-11T08:55:59Zhttp://cogprints.org/id/eprint/4273This item is in the repository with the URL: http://cogprints.org/id/eprint/42732005-05-02ZProperties of the Short Term Memory StructureProperties of a short term memory structure are discovered in the data of Rubin, Hinton and Wenzel (1999): Cued-recall probability and search time are linearly related from 6 seconds to 666 seconds after stimulus presentation with a zero probability of cued-recall at 2.6 seconds and a 100% recall probability at 1.3 seconds. This linear relationship defines a short term memory structure which is a moving structure: the memory structure travels away from the starting point of the search (suggesting that the starting points of the search and storage are the same), decaying with a rate proportional to the time it takes to find the structure. The travel speed is slower than Brownian motion. The incorrect recall time saturates, giving an upper limit for the number of neurons involved in the short term memory structure of 3*108 using an interneuron transfer time or 4 msecs or 3*106 using an neuron-neuron transfer time of 20msecs.Dr. Eugen Tarnow2006-01-06Z2011-03-11T08:56:14Zhttp://cogprints.org/id/eprint/4670This item is in the repository with the URL: http://cogprints.org/id/eprint/46702006-01-06ZThe Short Term Memory Structure In State-Of-The Art Recall/Recognition Experiments of Rubin, Hinton and WentzelProperties of a short term memory structure are discovered in the data of Rubin, Hinton and Wenzel (1999): Recall (recognition) probabilities and search times are linearly related through stimulus presentation lags from 6 seconds to 600 (350) seconds. This data suggest that only one memory structure is present in the Rubin, Hinton and Wenzel data. The data also suggest that the memory items have a finite effective size that shrinks to zero in a logarithmic fashion as the time since stimulus presentation increases, away from the start of the search. According to the logarithmic decay, the size of the memory items decreases to a couple of neurons at about 1200 seconds for recall and 350 seconds for recognition – this should be the time scale for a short term memory being converted to a long term memory. The incorrect recall time saturates, suggesting a limited size of the short term memory structure: the time to search through the structure for recall is 1.7 seconds. For recognition the corresponding time is about 0.4 seconds, a non-Sternberg experimental result to compare with the 0.243 seconds given by Cavanagh (1972)).Dr. Eugen Tarnow2002-12-18Z2011-03-11T08:55:07Zhttp://cogprints.org/id/eprint/2665This item is in the repository with the URL: http://cogprints.org/id/eprint/26652002-12-18ZHave brain dynamics evolved?
Should we look for unique dynamics in the sapient species?Ongoing "spontaneous" electrical field potentials of assemblies of neurons in the brains of diverse animal groups differ widely in character and amplitude without obvious explanation. There may be correlates with other measures of brain complexity, such as histological differentiation but there are so far no known differences between the EEG s of humans and other mammals or between mammals and reptiles, amphibians or fish, apart from amplitude. The proposition is defended that further search for descriptors or statistical, probably non-linear features of the time series will reveal consistent differences - meaning that we have so far missed major features of the natural history of EEGs, just as we have, thus far, relatively neglected the identification of features of the physiology of the brain relevant to its evolution of complexity through major grades of phyla, classes and orders.T.H. Bullock2003-02-17Z2011-03-11T08:55:10Zhttp://cogprints.org/id/eprint/2777This item is in the repository with the URL: http://cogprints.org/id/eprint/27772003-02-17ZHave brain dynamics evolved?
Should we look for unique dynamics in the sapient species?Ongoing “spontaneous” electrical field potentials of assemblies of neurons in the brains of diverse animal groups differ widely in character and amplitude without obvious explanation. There may be correlates with other measures of brain complexity, such as histological differentiation but there are so far no known differences between the EEG s of humans and other mammals or between mammals and reptiles, amphibians or fish, apart from amplitude. The proposition is defended that further search for descriptors or statistical, probably non-linear features of the time series will reveal consistent differences - meaning that we have so far missed major features of the natural history of EEGs, just as we have, thus far, relatively neglected the identification of features of the physiology of the brain relevant to its evolution of complexity through major grades of phyla, classes and orders.T.H. Bullock2001-12-05Z2011-03-11T08:54:50Zhttp://cogprints.org/id/eprint/1927This item is in the repository with the URL: http://cogprints.org/id/eprint/19272001-12-05ZNeuron Soma Size in the Left and Right Hippocampus of a Genius NEURON SOMA SIZE IN THE LEFT AND RIGHT HIPPOCAMPUS OF A GENIUS
D.W. Zaidel*
Dept Psychology, UCLA, Los Angeles, CA, USA
Underlying brain features of a genius are not understood. It is not
known if there is a smooth continuum between a genius and the thousands
of the brightest minds alive today. The few postmortem studies of brains
of remarkable mathematicians or physicists typically emphasized the
neocortex. In the present study, the hippocampus of Albert Einstein (AE)
was investigated postmortem. The importance of the hippocampus is
established for long-term, explicit, implicit, and episodic memory, and
establishment of semantic associations. A single microscope slide
(Nissl-stained stained in Harvey[Image]s lab not long after AE[Image]s
death at age 76 years) was available for the left and right sides. Soma
size of pyramidal neurons in coronal sections of AE[Image]s left and
right hippocampi were photographed, then digitized and systematically
measured on a computer in hippocampal subfields CA1, CA2, CA3, CA4, and
subiculum. An atypical left-right asymmetry emerged in AE, with soma
size being consistently and significantly larger in the left than in the
right side in all homologous subfields except for CA2, whereas in 10
ordinary adults, aged 22 to 84 years, there was minimal and inconsistent
soma size asymmetry in direction (left vs right) or extent. However, the
soma size variability revealed similarities in both AE and the ordinary
adults, particularly in hippocampal subfields CA1 and CA2, bilaterally.
The direction of the cell size asymmetry in AE[Image]s hippocampi could
simply reflect age-related changes in combination with unusual neuronal
connectivity of prenatal or experiential origin. This is difficult to
ascertain, and the relationship between the hippocampal status at the
time of his death and its role in his genius in his most creative years
is a matter for debate.Dahlia Zaidel2000-12-19Z2011-03-11T08:54:27Zhttp://cogprints.org/id/eprint/1163This item is in the repository with the URL: http://cogprints.org/id/eprint/11632000-12-19ZSuppression of displacement in severely slowed saccadesSeverely slowed saccades in <I>spinocerebellar ataxia</I> have previously been shown to be at least partially closed-loop in nature: their long duration means that they can be modified in-flight in response to intrasaccadic target movements. In this study, a woman with these pathologically slowed saccades could modify them in-flight in response to target movements, even when saccadic suppression of displacement prevented conscious awareness of those movements. Thus saccadic suppression of displacement is not complete, in that it provides perceptual information that is sub-threshold to consciousness but which can still be effectively utilised by the oculomotor system.Michael R MacAskillTim J AndersonRichard D Jones2000-05-09Z2011-03-11T08:53:42Zhttp://cogprints.org/id/eprint/143This item is in the repository with the URL: http://cogprints.org/id/eprint/1432000-05-09ZError detection and the Error-related ERP in patients with lesions involving the anterior cingulate and adjacent regionsEvidence indicates that the anterior cingulate region generates what appears to be a specific electrophysiological marker for the monitoring of error responses. When an auditory or visual stimulus is presented in such a way that the subject is likely to make an error, averaged encephalography (EEG) trials to erroneous responses consistently show a negative-going waveform which has been coined the error-related negativity (ERN). We examined ERNs in patients with a ruptured aneurysm of the anterior communicating artery (AACA), who are particularly prone to showing damage in the anterior cingulate and adjacent regions, and frequently display a variety of behavioral and cognitive disturbances such as disorientation, confabulation, apathy, unawareness of deficit, and problems of attention, control and monitoring. We found that these patients generally did not produce an ERN in comparison to healthy control participants suggesting that the anterior cingulate is essential for the ERN response. However, the patients' error rates were comparable to that of the controls and they showed a dissociation between overt error awareness and ERN production, suggesting that the ERN does not simply represent an error detection signal.Brigitte StemmerSidney J. SegalowitzWolfgang WitzkeSieglinde LacherPaul Walter Schönle2000-06-14Z2011-03-11T08:53:42Zhttp://cogprints.org/id/eprint/149This item is in the repository with the URL: http://cogprints.org/id/eprint/1492000-06-14ZTHE MIND AND BRAIN SCHOLAR AS A HITCH-HIKER IN POST-GUTENBERG GALAXY: PUBLISHING AT 2000 AND BEYONDElectronic journal (e-journal) publishing has started to change the ways we think about publish-ing. However, many scholars and scientists in the mind and brain sciences are still ignorant of the new possibilities and on-going debates. This paper will provide a summary of the issues in-volved, give an update of the current discussion, and supply practical information on issues re-lated to e- journal publishing and self-archiving relevant for the mind and brain sciences. Issues such as differences between traditional and e-journal publishing, open archive initiatives, world-wide conventions, quality control, costs involved in e-journal publishing, and copyright questions will be addressed. Practical hints on how to self-archive, how to submit to the e-journal Psycolo-quy, how to create an open research archive, and where to find information relevant to e-publishing will be supplied.Brigitte StemmerMarianne CorreYves Joanette2000-05-13Z2011-03-11T08:53:42Zhttp://cogprints.org/id/eprint/147This item is in the repository with the URL: http://cogprints.org/id/eprint/1472000-05-13ZThe study of the regenesis of mind in the 21st centuryThe enigma of consciousness and the brain-mind relationship will - most likely - be unveiled in the 21st century through the new technologies developed at the end of the 20th century and new technologies yet to come. The new technologies will be used to tackle the problem from evolu-tionary, developmental, normal and pathological brain functioning. A major contribution, how-ever, will surface when investigating a particular perspective of pathological brain functioning - a perspective that has not received any attention in the past: the investigation of the re-emergence of mind out of prolonged coma and coma like states.Paul Walter SchönleBrigitte Stemmer2000-02-28Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/141This item is in the repository with the URL: http://cogprints.org/id/eprint/1412000-02-28ZRegional differentiation of neuron morphology in human left and right hippocampus: Comparing normal to schizophreniaRegional differentiation based on size, form, and orientation angle of the soma of individual neurons in human post-mortem hippocampus was determined through correlations between pairs of hippocampal subfields in each side separately. The neurons were previously measured on a computer. In the normal cases, a left-right asymmetrical pattern of regional differentiation based on soma size emerged, while for form and orientation angle, the patterns appeared symmetrical. In schizophrenia, regional soma size, form, and orientation variability were expressed largely symmetrically. Regional correlations based on neuronal density revealed an asymmetrical hemispheric pattern in the normal cases versus a nearly symmetrical pattern in schizophrenia. Taken together, the inter-regional correlations favor a hippocampal landscape that deviates in each side from connectivity based on the canonical trisynaptic hippocampal circuitry. It is proposed that during morphogenesis, rudimentary inter-regional networks are formed through specific interactions between regional neurons; these networks are present in the adult hippocampus and may be vulnerable in brain diseases.D. W. Zaidel2000-07-10Z2011-03-11T08:53:42Zhttp://cogprints.org/id/eprint/152This item is in the repository with the URL: http://cogprints.org/id/eprint/1522000-07-10ZQuantitative morphology of human hippocampus early neuron developmentBackground: Previous findings in adults revealed significant hemispheric asymmetry in size of neuronal somata in hippocampal subfield CA2 (the resistant sector) with no age-related changes. Paucity of quantitative data on the developmental status of these protected neurons has led to the investigation of their morphology in comparison to neurons in adjacent subfield CA3, bilaterally. Methods: Bilateral coronal sections from postmortem hippocampus, 24 and 76 weeks postmenstrual age (gestational age plus postnatal age) were studied. The neurons were digitized and measured on a computer. Results: Soma size correlated positively and significantly with age in CA2 and CA3, bilaterally. CA2 somata were significantly larger (left 34%, right 32%) than adjacent CA3 somata. Variability in soma form or size increased appreciably with age, in both subfields, bilaterally, while variability in soma orientation was weakly correlated with brain growth. Conclusions: The results suggest that in early development there are similarities in hemispheric growth patterns in CA2 and CA3. Large CA2 soma size implies axonal connectivity to distantly located targets very early in development. The results have functional implications, including memory, to brain developmentDahlia W. Zaidel1999-07-14Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/106This item is in the repository with the URL: http://cogprints.org/id/eprint/1061999-07-14ZThe Future of Research on Electroreception and Electrocommunication.Besides the rounding out of presently active areas, six are selected for predictions of marked advance. (1) Most discoveries will be in cellular componentry and molecular mechanisms for one or another class of receptors or central pathways. (2) More major taxa will be found with electroreceptive species, possibly birds, reptiles or invertebrates, representing independent evolutionary "inventions". (3) Electric organs with weak and episodic electric discharges will be found in new taxa; first, among siluriforms. (4) New examples are expected, like lampreys, where synchronized muscle action potentials add up to voltages in the range of weakly electric fish. Some of these will look like intermediates in the evolution of electric organs. (5) Ethological significance will be found for a variety of known physiological features. Exs.: uranoscopids, skates and weakly electric catfish with episodic electric discharges of unknown role; electroreceptive ability of some of the diverse group having Lorenzinian-type ampullae (besides elasmobranchs) including lampreys, chimaeras, lungfish, sturgeons, paddlefish, and salamanders; gymnotiform and mormyrid detection of capacitive component of impedance. (6) The organization of some higher functions in the cerebellum and forebrain will gradually come to light.Theodore H. Bullock1999-12-15Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/125This item is in the repository with the URL: http://cogprints.org/id/eprint/1251999-12-15ZIntroductionThe introduction to the special issue briefly discusses the origins and development of the word "pragmatics", pragmatic theory and its application to neurolinguistics. The special issue covers a total of 11 articles investigating pragmatic and neuropragmatic issues from different theoretical, experimental and clinical perspectives.Brigitte Stemmer2000-01-21Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/128This item is in the repository with the URL: http://cogprints.org/id/eprint/1282000-01-21ZNeuroethology has pregnant agendasTwo of the many agendas of neuroethology are illustrated with examples. (1) What cells or assemblies of cells and what patterns of activity are sufficient to accomplish recognition of ethologically important stimulus configurations and initiation of behavioral action? The theme is the opportunities available in relatively neglected approaches to these objectives. As an example, the approach is developed of gentle microstimulation of loci in the brain where cells have been found responsive to complex, natural stimuli, under conditions conducive to the performance of tell-tale behavior. Other approaches include (a) microinjection of modulatory substances into regions with such complex recognition cells and (b) recording in efficient and informative ways, by using multiple electrode arrays, recording wideband activity, in behaving animals. (2) What brain and behavior differences has evolution produced between major taxa at distinct grades of complexity? Emphasized are our relative ignorance of basic aspects of connectivity, physiology and cognitive capacities in the major grades and the probability of surprises from new studies that employ comparison.T.H. Bullock2005-06-05Z2011-03-11T08:56:04Zhttp://cogprints.org/id/eprint/4376This item is in the repository with the URL: http://cogprints.org/id/eprint/43762005-06-05ZNeuronal connectivity, regional differentiation, and brain damage in humans. When circumscribed brain regions are damaged in humans, highly specific iimpairments in language, memory, problem solving, and cognition are observed. Neurosurgery such as "split brain" or hemispherectomy, for example has shown that encompassing regions, the left and right cerebral hemispheres each control human behavior in unique ways. Observations stretching over 100 years of patients with unilateral focal brain damage have revealed, withouth the theoretical benefits of "cognitive neuroscience" or "cognitive psychology," that human behavior is indeed controlled by the brain and its neurons.Dahlia W. Zaidel2000-02-02Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/136This item is in the repository with the URL: http://cogprints.org/id/eprint/1362000-02-02ZPower spectra of ongoing activity of the snail brain can discriminate odorantsTo test the hypothesis that different odorants are likely to cause distinctive changes in the ongoing electrical activity of populations of olfactory cells, we investigated field potentials (FP) in the Helix brain and their alterations by odorants as seen by semimicroelectrodes in an isolated preparation of the rostrum with ist olfactory organ and whole central nervous system. Five pure chemicals and two natural odorants were applied as stimulants. Signals recorded both from the procerebrum (PC) and the visceral ganglion (VG) were analyzed. In the PC the five pure chemical odorants induce stimulus-specific characteristic responses, mainly in the low frequency range (<15 Hz). Regardless of odor intensity, the frequency of the peak power of sustained induced activity is constant for each chemical: ammonia at 0.2 ( <0.02 Hz; formic acid at 0.36 ( 0.03 Hz; 2-pentanol at 0.48 ( 0.04 Hz; 2-butanol at 0.67 ( 0.03 Hz; ethanol at 1.31 ( 0.09 Hz (means ( 95% confidence limits). These peak power frequencies, which we define as (odor-specific frequencies(, are confined to the low frequency range of < 2.5 Hz. Those of natural odorants are: onion (0.36 ( 0.14 Hz) and apple (1.1 ( 0.25 Hz). The activities evoked in the PC propagate to VG. The order of behavioral aversion determined by withdrawal reactions of the tentacles, 1% ammonia > formic acid > 2-pentanol > 2-butanol > ethanol, coincides with (the order of molecular affinity( as well as with the sequence of peak power frequencies. There seems to be a strong correlation among behavioral valence, chemical nature of an odorant, and odor-specific frequency. The finding that, in the Helix olfactory center, odor input is processed as odorant specific low frequency FP activity may represent some general phenomena of olfactory information processing.A. SchuttE. BasarT.H. Bullock2000-02-02Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/137This item is in the repository with the URL: http://cogprints.org/id/eprint/1372000-02-02ZSlow potentials in the brain: still little understood but gradually getting analytical attentionTwo classes of electrical activity in the central nervous system have been known for a long time: spikes with synaptic potentials and "slow" fluctuations (components mainly below ca. 100 Hz). Their relations to each other are still little known and an unfortunate schism persists in mutual disparagement by investigators who chiefly study one class or the other. The news I wish to highlight is that this schism is waning and this essay will be outmoded as more workers study both. I focus here on the class of slow potentials which in certain respects is the more neglected. This class should extend down into the less-known "infraslow" domain (power mainly below 0.1 Hz) - omnipresent, higher in amplitude and clearly significant functionally.T.H. Bullock1999-07-23Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/112This item is in the repository with the URL: http://cogprints.org/id/eprint/1121999-07-23ZSensory processing in the pallium of a mormyrid fishTo investigate the functional organization of higher brain levels in fish we test the hypothesis that the dorsal gray mantle of the telencephalon of a mormyrid fish has discrete receptive areas for several sensory modalities. Multiunit and compound field potentials evoked by auditory, visual, electrosensory and water displacement stimuli in this weakly electric fish are recorded with multiple semimicroelectrodes placed in many tracks and depths in or near area dorsalis telencephali, pars medialis (Dm). Most responsive loci are unimodal; some respond to two or more modalities. Each modality dominates a circumscribed area, chiefly separate. Auditory and electrical responses cluster in the dorsal 500 m of rostral and caudolateral Dm, respectively. Two auditory subdivisions underline specialization of this sense. Mechanoreception occupies a caudal area overlapping electroreception but centered 500 m deeper. Visual responses scatter widely through ventral areas. Auditory, electrosensory and mechanosensory responses are dominated by a negative wave within the first 50 ms, followed by 15-55 Hz oscillations and a slow positive wave with multiunit spikes lasting from 200-500 ms. Stimuli can induce shifts in coherence of certain frequency bands between neighboring loci. Every electric organ discharge command is followed within 3 ms by a large, mainly negative but generally biphasic, widespread corollary discharge. At certain loci large, slow ("delta F") waves usually precede transient shifts in electric organ discharge rate. Sensory evoked potentials in this fish pallium may be more segregated than in elasmobranchs and anurans and have some surprising similarities to those in mammals. Key Words: cerebral cortex; corollary discharge; induced rhythms; evoked potential; gamma band; lateral line; mormyrid.James C. PrechtlGerhard von der EmdeJakob WolfartSaçit KaramürselGeorge N. AkoevYuri N. AndrianovTheodore H. Bullock1999-07-06Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/105This item is in the repository with the URL: http://cogprints.org/id/eprint/1051999-07-06ZSubmicrosecond pacemaker precision is behaviorally modulated: The gymnotiform electromotor pathwayWhat are the limits and modulators of neural precision? We address this question in the most regular biological oscillator known, the electric organ command in the brainstem of wave-type electric fish. The oscillating electric organ discharge (EOD), used in electrolocation and communication, has high regularity measured by a low coefficient of variation (CV as low as 2 x 10-4) in five species from three families ranging in mean EOD from 70 to 1250 Hz. Intracellular recording in the nucleus (Pn) pacing EODs reveals that individual Pn neurons also display an extremely low CV. While the CV can remain at its minimum for hours, it varies with novel environmental conditions, during communication, and spontaneously. Spontaneous changes occur as abrupt steps (250 msec), oscillations (35 Hz), or slow ramps (1030 sec). Several findings suggest that these changes are under active control and depend on behavioral state. Mean EOD frequency and CV can change independently. CV often decreases in response to stimuli. Lesions of one of the two inputs to the Pn had more influence on CV than lesions of the other inputKatherine T. MoortgatClifford H. KellerTheodore H. BullockTerrence J. Sejnowski1998-03-16Z2011-03-11T08:53:36Zhttp://cogprints.org/id/eprint/5This item is in the repository with the URL: http://cogprints.org/id/eprint/51998-03-16ZDiscovering Structure From Motion In Monkey, Man And MachineThe ability to obtain three-dimensional structure from visual motion is important for survival of human and non-human primates. Using a parallel processing model, the current work explores how the biological visual system might solve this problem and how the neurophysiologist might go about understanding the solution.Ralph M Siegel1998-03-30Z2011-03-11T08:53:37Zhttp://cogprints.org/id/eprint/11This item is in the repository with the URL: http://cogprints.org/id/eprint/111998-03-30ZEarly cortical activation indicates preparation for retrieval of memory for faces: an event-related potential studyEvent-related brain potentials (ERPs) were used to investigate thetime course of memory processes following the presentation of faces. Following a phase in which subjects were asked to memorise faces presented on a computer screen (study phase) they had to distinguish the previously presented faces from others new to the experiment (test phase). We found that in a time period from 250-350 ms after onset of stimulus presentation ERPs show higher negativity for both repeated and novel faces in the test phase compared to the study phase. This situation dependent effect is most pronounced in occipito-temporal regions. We conclude that memory retrieval for faces is a sequential process: The early part of this process constitutes preparation for the retrieval of stored information, and a later part of the process comprises the discrimination between repeated and novel faces.W EndlP WallaG LindingerW LalouschekF G BarthL DeeckeLang W1998-03-13Z2011-03-11T08:53:36Zhttp://cogprints.org/id/eprint/3This item is in the repository with the URL: http://cogprints.org/id/eprint/31998-03-13ZExperiments in Movement Using DC-EEG, MEG, SPECT and FMRIOur volitional self-initiated acts are preceded by the Bereitschaftspotential (BP) or readiness potential [34,35]. The BP has an early component (BP1) and a late component (BP2, see Fig. 1). The early component BP1 lasts from the very beginning of the BP (1-2 s or more prior to movement onset depending on the complexity of the movement) to app. ½ s prior to movement onset and the late component BP2 lasts from ½ s before to the onset of movement itself (s 0 in Fig. 1). BP1 is symmetrical even for unilateral movement, while BP2 is larger over the contralateral hemisphere. Luder DeeckeW LangR BeisteinerF UhlG LindingerR Q Cui1999-07-14Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/107This item is in the repository with the URL: http://cogprints.org/id/eprint/1071999-07-14ZForays with the additive periodogram applied to the EEG.The most information-rich measure of the working brain is the electrical activity, recorded as wideband, extracellular local field potentials from multiple sites, in extent and depth, with millisecond and millimeter resolution. We still lack a common view of the electrical activity in terms of simple description - which must precede explanation in terms of mechanisms. The situation is much like the diverse views on the nature and characteristics of a jungle. We have elsewhere addressed related questions. (i) How much of the wideband activity is stochastic - concluding that a significant and highly labile amount of coherence and bicoherence bespeak temporal fine structure and cooperativity. (ii) How much fine structure is spatial, concluding that differentiation increases as the volume sampled is smaller (Bullock et al. 1995a,b, 1997).T.H. BullockJ.T. EnrightK.M. Chong1998-03-30Z2011-03-11T08:53:36Zhttp://cogprints.org/id/eprint/10This item is in the repository with the URL: http://cogprints.org/id/eprint/101998-03-30ZMovement-Related Potentials and Magnetic Fields: New Evidence for SMA Activation Leading MI Activation Prior to Voluntary MovementMovement is the essence of life. Without movement one cannotachieve anything. Consequently, during evolution, movement has been optimized to highest levels of precision. Visible sign of the evolution of movement is that more and more brain has been assigned for motor purposes. A carnivore´s motor cortex is just a `dimple' in its brain supported by merely a minimal frontal cortex. In the primate, the dimple evolved into a motor strip and shifted from an anterior to a central position, in order to accommodate more and more frontal brain. Homo sapiens neanderthalensis with his sloping forehead still had less frontal cortex than Homo sapiens sapiens. In the latter, about half the cortex is pre-rolandic, assigned to motor purposes in the broader sense, i.e. including areas that supply to motor such as premotor, prefrontal, etc. areas. These frontal supplier areas to motor are involved in functions such as motivation, preparation, volition, will, planning, foresight, active anticipation, precaution, intent to act, purposefulness, goal-directedness, etc. i.e. all these functions are frontal in location, and the function of the frontal lobes seems to be almost entirely behavour-related including - in man - all the future-related behavioural aspects. A special role may be assigned to the frontomesial cortex including the supplementary motor area (SMA) and the cingulate motor area (CMA). The brain apparatus supporting motor is among the most recent and highly organized cerebral structures (neoneocortex), and the corticalization of movement developed in a saltatory way in primate phylogenesis. There are many movements man can perform, but basically there are only two primordial categories of movements: Self-initiated voluntary movements = actions and responsive (externally triggered) movements = re-actions. The first category is preceded by a Bereitschaftspotential, the latter occurs between S1 and S2 of a re-action paradigm (Walter et al. 1964). Regarding the BP, recent evidence using multichannel (64) DC-EEG (time constant [tau] = [infinity]) computer-assisted amplification proved that the earliest activity occuring is over the SMA/CMA. Only later comes the primary motor area (MI) into play. This was also shown using current source density techniques (laplacians with spline interpolation), multichannel (143) MEG and FMRI.L DeeckeW LangR BeisteinerG LindingerR Q Cui2000-07-10Z2011-03-11T08:53:42Zhttp://cogprints.org/id/eprint/151This item is in the repository with the URL: http://cogprints.org/id/eprint/1512000-07-10ZBrain asymmetry and facial attractiveness: Facial beauty is not simply in the eye of the beholder.We recently reported finding asymmetry in the appearance of beauty on the face [39]. Here we investigated whether facial beauty is a stable characteristic (on the owner's very face) or is in the perceptual space of the observer. We call the question 'the owner versus observer hypothesis'. We compared identity judgements and attractiveness ratings of observers. Subjects viewed left-left and right-right composites of faces and decided which most resembled the normal face (Experiment 1). Identity judgements (resemblance) are known to be associated with perceptual factors in the observer. Another group viewed the same normal faces and rated them on attractiveness (Experiment 2). In each experiment there were two separate viewing conditions, original and reversed (mirror-image). Lateral reversal did affect the results of Experiment 1 (confirming previous findings [3,18]) but did not affect the results of Experiment 2. The fact that lateral reversal did not affect the results of Experiment 2 suggests that facial attractiveness is more dependent on physiognomy (of the owner) and less dependent on an asymmetrical perceptual process (in the observer) than is facial identity. The results are discussed in the context of beautys biological significance and facial processing in the brain.Audrey C. ChenCraig GermanDahlia W. Zaidel1999-10-27Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/122This item is in the repository with the URL: http://cogprints.org/id/eprint/1221999-10-27ZBicoherence of intracranial EEG in sleep, wakefulness and seizuresThe hypothesis that the intracranial EEG has local structure and short-term non-stationarity is tested with a little-studied measure of nonlinear phase coupling, the bicoherence in human subdural and deep temporal lobe probe data from 11 subjects during sleeping, waking and seizure states. This measure of cooperativity estimates the proportion of energy in every possible pair of frequency components, F1, F2 (from 1-50 Hz in this study), that satisfies the definition of quadratic phase coupling (phase of component at F3 , which is F1+F2, equals phase of F1 + phase of F2). Derived from the bispectrum, which segregates the nonGaussian energy, auto-bicoherence uses the frequency components in one channel; cross-bicoherence uses one channel for F1 and F2 and another for F3. These higher order spectra are used in physical systems for detection of episodes of nonlinearity and transients, for pattern recognition and robust classification, relatively immune to Gaussian components and low signal to noise ratios. Bicoherence is found not to be a fixed character of the EEG but quite local and unstable, in agreement with the hypothesis. Bicoherence can be quite different in adjacent segments as brief as 1.6 s as well as adjacent intracranial electrodes as close as 6.5 mm, even when the EEG looks similar. It can rise or fall steeply within millimeters. It is virtually absent in many analysis epochs of 17s duration. Other epochs show significant bicoherence with diverse form and distribution over the bifrequency plane. Isolated peaks, periodic peaks or rounded mountain ranges are either widely scattered or confined to one or a few parts of the plane. Bicoherence is generally an invisible feature: one cannot usually recognize the responsible form of nonlinearity or any obvious correlate in the raw EEG. During stage II/III sleep overall mean bicoherence is generally higher than in the waking state. During seizures the diverse EEG patterns average a significant elevation in bicoherence but have a wide variance. Maximum bispectrum, maximum power spectrum, maximum and mean bicoherence, skewness and asymmetry all vary independently of each other. Cross-bicoherence is often intermediate between the two auto-bicoherence spectra but commonly resembles one of the two. Of the known factors that contribute to bicoherence, transient as distinct from ongoing wave forms can be more important in our data sets. This measure of nonlinear higher moments is very sensitive to weak quadratic phase coupling,; this can come from several kinds of waveforms. New methods are needed to evaluate their respective contributions. Utility of this descriptor cannot be claimed before more carefully defined and repeatable brain states are studied.T.H. BullockJ.Z. AchimowiczR.B. DuckrowS.S. SpencerV.J. Iragui-Madoz1999-07-15Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/108This item is in the repository with the URL: http://cogprints.org/id/eprint/1081999-07-15ZComparative Physiology of Acoustic and Allied Central AnalyzersTo exploit comparisons among classes of vertebrates and invertebrates, and between higher and lower levels of the brain, and between modalities, some important needs and opportunities for new research into the way central processing of acoustic input takes place are pointed out. Most of these are suggested by unfamiliar results on fish and reptiles that call for new controls in mammalian experiments as well as more systematic study of nonmammalian taxa. Three frameworks or basic agendas are outlined: (i) systematic comparison of dynamical properties to acoustic variables, including especially repetition at different rates and the related states of expectation; (ii) comparison of response measures, including especially sequences such as oscillations and measures of assembly cooperativity such as synchrony, coherence and bicoherence; and (iii) comparison of auditory subsystems, including especially modal categories such as complex feature selective regions and small sets.Theodore H. Bullock1998-03-19Z2011-03-11T08:53:36Zhttp://cogprints.org/id/eprint/7This item is in the repository with the URL: http://cogprints.org/id/eprint/71998-03-19ZModulation of Responses to Optic Flow in Area 7a by Retinotopic and Oculomotor Cues in MonkeyPerception of two-and-three dimensional optic flow critically depends upon extrastriate cortices that are part of the "dorsal stream" for visual processing. Neurons in area 7a, a sub-region of the posterior parietal cortex, have a dual sensitivity to visual input and to eye position. The sensitivity and selectivity of area 7a neurons to three sensory cues were studied: optic flow, retinotopic stimulus position, and eye position. The visual response to optic flow was modulated by the retinotopic stimulus position and by the eye position in the orbit. The position dependence of the retinal and eye position modulation (i.e. gain field) were quantified by a quadratic regression model that allowed for linear or peaked receptive fields. A local maximum (or minimum) in both the retinotopic fields and the gain fields was observed suggesting that these sensory qualities are not necessarily linearly represented in area 7a. Neurons were also found that simply encoded the eye position in the absence of optic flow. The spatial tuning for the eye position signals upon stationary stimuli and optic flow was not the same suggesting multiple anatomical sources of the signals. These neurons can provide a substrate for spatial representation while primates move in the environment.Heather L ReadRalph M Siegel2000-01-21Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/127This item is in the repository with the URL: http://cogprints.org/id/eprint/1272000-01-21ZNeuroethology of ZooplanktonWhereas the neural analysis of behavior of planktonic species and stages has been relatively neglected, we have many clues that it is going to be rich, diverse and interesting. The aims of this contribution are to defend that statement, with selected examples, and to suggest that neural analysis, particularly sensory physiology, has great explanatory power of ecologically significant behavior. I have to begin with a personal note about plankton, recalling the lasting impression made long ago by a film on invertebrates in the Arctic where scyphomedusan jellyfish were pulsing at a rate well within the range familiar in summer temperate waters, warmer by 20º C. I must have been influenced by this observation and my own experiences in a study of the neural basis of fluctuations in the rate of pulsation of medusae (Bullock 1943), some of which was made in December 1941 in Pensacola, where my wife and I collected Rhopilema cruising at random in the Sound, stopped now and then by Army bridge guards concerned about saboteurs in that first fortnight after Pearl Harbor. At any rate, by the early fifties about half of my laboratory group was devoted to the physiological ecology of temperature acclimation in marine invertebrates. That field, which I left in the early sixties, still offers a challenge in the ecologically fundamental question of why some species are able to acclimate much more than others. The proposal I made in 1955, that different rates in the same organism acclimate to different degrees, resulting in greater disharmony in some species than others, may still be viable and most likely applies to rate processes in sensory and central nervous functions, among others. Medusae are large animals, relatively, although generally treated as planktonic. The first reaction from most workers when neurophysiology of plankton is mentioned concerns their small size or gelatinous nature. The first message I bring is not new but also not widely appreciated.T.H. Bullock1999-07-26Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/113This item is in the repository with the URL: http://cogprints.org/id/eprint/1131999-07-26ZSignals and signs in the nervous system: The dynamic anatomy of electrical activityThe dichotomy between two groups of workers on neuroelectrical activity is retarding progress. To study the interrelations between neuronal unit spike activity and compound field potentials of cell populations is both unfashionable and technically challenging. Neither of the mutual disparagements is justified: that spikes are to higher functions as the alphabet is to Shakespeare and that slow field potentials are irrelevant epiphenomena. Spikes are not the basis of the neural code but of multiple codes that coexist with nonspike codes. Field potentials are mainly information-rich signs of underlying processes, but sometimes also signals for neighboring cells, that is, exert influence. This paper concerns opportunities for new research with many channels of wideband (spike and slow wave) recording. A wealth of structure in time and 3-dimensional space, is different at each scale, micro-, meso- and macroactivity. The depth of our ignorance is emphasized to underline the opportunities for uncovering new principles. We cannot currently estimate the relative importance of spikes and synaptic communication vs extrasynaptic, graded signals. In spite of a preponderance of literature on the former, we must consider the latter as probably important. We are in a primitive stage of looking at the time series of wideband voltages in the compound, local field potentials and of choosing descriptors that discriminate appropriately among brain loci, states (functions), stages (ontogeny, senescence) and taxa (evolution). This is not surprising since the brains in higher species are surely the most complex systems known. They must be the greatest reservoir of new discoveries in nature. The complexity should not deter us but a dose of humility can stimulate the imaginative juices.T.H. Bullock2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5312This item is in the repository with the URL: http://cogprints.org/id/eprint/53122006-12-22ZPrenatal growth markers in schizophrenia: a monozygotic co-twin control study.
OBJECTIVE: This co-twin study investigated monozygotic twins who were discordant for schizophrenia for evidence of prenatal growth differences between the affected and well co-twins. METHOD: Four dermatoglyphic markers of prenatal growth were obtained by established procedures from 26 monozygotic twin pairs discordant for schizophrenia, 13 monozygotic twin pairs concordant for schizophrenia, and several normal monozygotic twin samples. RESULTS: The a-b ridge count differences between the affected and well co-twins were greater than those found for concordant and normal monozygotic pairs. In comparison with their well co-twins, the affected twins, in discordant pairs, had developed fewer epidermal ridges in the a-b interdigital area of their right palms. In contrast, no significant differences were found between the affected twins and their well co-twins on markers associated with fetal development before 13 or after 15 weeks estimated gestational age. CONCLUSIONS: Because the a-b ridges are known to complete development between 13 and 15 weeks estimated gestational age, the results provide physical evidence suggesting that the schizophrenia-affected monozygotic twins alone experienced a time-specific and time-limited dysgenesis during this time. Commonalities in the ontogeny of epidermal and neurological structures are discussed.JO DavisHS Bracha1998-03-16Z2011-03-11T08:53:36Zhttp://cogprints.org/id/eprint/8This item is in the repository with the URL: http://cogprints.org/id/eprint/81998-03-16ZOn the origins of aperiodicities in sensory neuron entrainmentAperiodic entrainment to rhythmic sensory input was obtained with either a single neuron or an excitatory network model, without addition of a stochastic or "noisy" element. The entrainment properties of primary sensory neurons were well captured by the dynamics of the Hodgkin-Huxley ordinary differential equations with a quiescent resting state or threshold for spike output. The frequency-amplitude parameter space was compressed and aperiodic regimes were small in comparison to those of periodically activated pacemaker like neurons. Transitions between phase-locked and aperiodic entrainment patterns were predictable and determined by the equation dynamics; supporting the contention that some aperiodicities observed ${in}$ ${situ}$ arise from the inherent membrane properties of neurons. When the rhythmically activated neuron was embedded in an excitatory network of Hodgkin-Huxley neurons with heterogeneous synaptic delays, aperiodic entrainment patterns were more frequently encountered and these were associated with asynchronous output from the network. Embedding the rhythmically activated neuron in a network with synaptic delays, greatly reduced the range of entrained spike frequencies. Other biological mechanisms of modifying the entrainment properties and promoting aperiodic entrainment are discussed.Heather L ReadRalph M Siegel1998-04-15Z2011-03-11T08:53:37Zhttp://cogprints.org/id/eprint/15This item is in the repository with the URL: http://cogprints.org/id/eprint/151998-04-15ZPlanning, preparation, execution, and imagery of volitional actionThere are different motor sets, which a human subject can be in or act from: He or she can be in a self-initiated voluntary movement set (action) or in a response set (re-action). Also, imagery sets are available that are necessary for the acquisition and practice of skill. Most important are such imagery sets for rehearsal in theatre, dance, music, sports, combat, etc.Lüder Deecke2000-01-24Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/130This item is in the repository with the URL: http://cogprints.org/id/eprint/1302000-01-24ZTheodore Holmes BullockThey tell me I was born on a sunny Sunday in May in Nanking, China, in 1915. I was the second of four children of Presbyterian missionary parents, Amasa Archibald Bullock and Ruth Beckwith, who had come to China in 1909, honeymooning on the way for six months in Europe and India. Several years before, father had answered a call for western teachers, published by the Empress; he spent a contract year in Chengtu, in western Szechuan, teaching chemistry, his major subject at U.C. Berkeley. He fell in love with the people, their eagerness to listen, and their respect for learning. Seeing a niche that called him, in the scattered experiments with western style education, especially teacher training, he returned to the states to take a master's degree in education at Chicago and then advanced work in psychology with Thorndike at Columbia. His college roommate's sister was preparing to be a missionary in Hartford Theological Seminary and they had corresponded but not met before he came to visit and in four days secured her assent to return with him and spend a life in China. He joined the faculty of the University of Nanking to start its normal school and, among other activities, its program in agriculture. The still extant guest book of our home shows the signatures of Sun Yat Sun, then President of China, and several members of his cabinet.T.H. Bullock2000-08-15Z2011-03-11T08:54:22Zhttp://cogprints.org/id/eprint/919This item is in the repository with the URL: http://cogprints.org/id/eprint/9192000-08-15ZThe case for a relationship between human memory, hippocampus and corpus callosumUnilateral brain damage which includes the hippocampus leads to memory impairments consistent with hemispheric specialization on the same side. Damage to the corpus callosum, the major connecting pathway between the left and right hemispheres, also leads to memory impairments. This suggests both hemispheric specialization on the hippocampal level and a critical role for the corpus callosum in memory functions. A complete hippocampal formation is present on either side of the brain but traditionally only one is studied. However, a comparison between the neuronal populations in the hippocampus on both sides revealed asymmetry in connectivity among hippocampal subfields. The profile of memory impairments of commissurotomy (split-brain) patients is described. The results are discussed in terms of a relationship between hippocampus and corpus callosum in humans. As hemispheric specialization evolved, inter-hippocampal connections became less important and the corpus callosum became prominent in memory functions.
Dahlia W. Zaidel2000-01-31Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/133This item is in the repository with the URL: http://cogprints.org/id/eprint/1332000-01-31ZEEG coherence has structure in the millimeter domainSubdural recordings from 8 patients via rows of eight electrodes with either 5 or 10 mm spacing plus depth recordings from 3 patients with rows of 8-12 electrodes either 6.5 or 9 mm center-to-center were searched for signs of significant local differentiation of coherence calculated between all possible pairs of loci. EEG samples of 2-4 min were taken during four states: alertness, stage 2-3 sleep, light surgical anesthesia permitting the patient to respond to questions or commands, and electrical seizures. Coherence was computed for all frequencies from 1-50 Hz or 0.3-100 Hz and then compared for 6 or 7 narrower bands between 2 and 70 Hz. In both the subdural surface samples and those from temporal lobe depth electrode arrays coherence declines with distance between electrodes of the pair, on the average. This is nearly the same for all frequency bands. Whether computed for 5, 20 or 60 s epochs, coherence pooled across all pairs of a given separation, in a given subject, differs only slightly, in the direction of lower coherence for longer samples, indicating good stationarity of the samples chosen. For middle bands like 8-13 and 13-20 Hz, mean coherence typically declines most steeply in the first 10 mm, from values indistinguishable from 1.0 at <0.5 mm distance to 0.5 at 5-10 mm and to 0.25 in another 10-20 mm in the subdural surface data. Temporal lobe depth estimates decline ca. half as fast; coherence 0.5 extends for 9-20 mm and 0.25 for another 20-35 mm. Low frequency bands (1-5, 5-8 Hz) usually fall slightly more slowly than high frequency bands (20-35, 35-50 Hz) but the difference is small and variance large. The steepness of decline with distance in humans is significantly but only slightly smaller than that we reported earlier for the rabbit and rat, averaging < one half. Local coherence, for individual pairs of loci, shows differentiation in the millimeter range, i.e. nearest neighbor pairs may be locally well above or below average and this is sustained over minutes. Local highs and lows tend to be similar for widely different frequency bands. Coherence varies quite independently of power, although they are sometimes correlated. Regional differentiation is statistically significant in average coherence among pairs of loci on temporal vs frontal cortex or lateral frontal vs subfrontal strips in the same patient, but such differences are usually small. We could not test how consistent they are over hours or between patients. Differences between left and right hemispheres, whether symmetrical pairs or pooled from two or more lobes on each side, can be quite large; in our patients the right side is usually higher, especially in the waking state. Brain state has a large influence. Slow wave sleep usually shows slightly more coherence at each distance, in all bands, compared to the waking EEG, but not consistently. Coherence at a given distance or its rate of decline with distance is a more direct measure of synchrony than naked-eye "synchronization," which is dominated by the power spectrum. Among the range of EEG states classified as seizures, coherence varies widely but averages higher by 0.05-0.2 than in pre-ictal states, usually in all frequencies when computed over the whole seizure but much more in the higher bands during the height of the electrical paroxysm. The findings point to still finer structure and more variance with closer spacing of electrodes. They could not predict the known large scale coherence between scalp electrodes, but are not in conflict with them. Scalp recording blurs the finer spatial structure, but reveals macrostructure missed by subdural and depth recording with limited numbers of channels. The strong tendency for correlated fluctuations across frequency bands is contrary to expectation from the common model of independent oscillators.T.H. BullockM. McCluneJ. AchimowiczIragui-Madoz V.J.Duckrow R.B.Spencer S.S.1999-07-22Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/110This item is in the repository with the URL: http://cogprints.org/id/eprint/1101999-07-22ZNeural Integration at the Mesoscopic Level: the Advent of some Ideas in the Last Half CenturyHistory seen by a professional historian, based only on the documented record, always incomplete and liable to bias, can be unreliable. Modern history seen by a protagonist must surely be among the most unreliable. My only excuse for this effort is that I was invited by the relevant Society committee. My reason for accepting is that I feel even the fragmentary part of neuroscience I can speak about is a human drama, romantic and exciting, and a flood on which we are floating, unable to dump the baggage of past biases. Our points of view, priorities, and positions on all the controversial issues and even the well established, noncontroversial ones, are not as rational as we would like to think but are strongly conditioned by where we came from. I will depend mainly on selected vignettes of the way things looked when I was a student, a young postdoctoral fellow and an Assistant Professor, to compare with the way they look to me or to others now, in each of half a dozen mesoscopic domains. I mean by mesoscopic domains the middle levels - those in between the most basic subcellular or molecular and the higher levels of learning and cognition. The half dozen domains constitute of course, anything but a representative fraction of neuroscience. I believe, however, that they add up to a nontrivial segment of the big picture with respect to the integrative aspects of our science. Most of the fronts that grew into today's popular branches of our science are not represented but a small set of particular interest and probability of further surprises.Theodore H. Bullock2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5314This item is in the repository with the URL: http://cogprints.org/id/eprint/53142006-12-22ZPrenatal development of monozygotic twins and concordance for schizophreniaWhile twin concordances for schizophrenia have been used to estimate heritability and to develop genetic models, concordances in subtypes of monozygotic (MZ) twins can also be used to investigate the influence of prenatal development in the etiology of mental illness. We used within-pair variability and mirroring of fingerprints to estimate retrospectively the placentation status of concordant and discordant MZ twins. The results indicate that concordant MZ pairs were more likely to have been monochorionic (MC) and to have shared a single placenta, whereas discordant MZ pairs appear more likely to have been dichorionic (DC) with separate placentas. Pairwise concordances for MZ twins without MC markers averaged 10.7 percent. In contrast, concordances for MZ twins with one or more MC markers averaged 60 percent. This suggests that simple MZ concordance rates may overestimate schizophrenia heritability and that prenatal development may also be important in the etiology of schizophrenia. Because MC (but not DC) twins usually share fetal blood circulation and hence are likely to share infections, these results are consistent with the hypothesis that fetal infections may be a significant etiological factor in schizophrenia.
JO DavisJA PhelpsHS Bracha2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5300This item is in the repository with the URL: http://cogprints.org/id/eprint/53002006-12-22ZSubclinical microcrania, subclinical macrocrarnia, and fifth-month fetal markers (of growth retardation or edema) in schizophrenia: a co-twin control study of discordant monozygotic twins.Summary: We tested the hypothesis that gestational injuries in some patients with schozophrenia would leave their mark as a subtle reduction in head circumference (subclinical microcrania).
Conclusions: The head circumferences of all subjects were in the normal range. Decreased head circumference in affected MZ co-twins (relative to unaffected MZ co-twin) characteriazes discordant MZ pairs with larger finger-ridge-count differences (i.e., second-trimester fetal-size differences). This study using ideal genetic controls suggests that, while present only in some patients with schizophrenia, the decrease in head circumference is most likely a consequence of in-utero nonshared environmental deleterious events manifesting as groth retardation or as fetal edema and occurring around the fifth prenatal month. HS BrachaP GilB LangeJ GilderEF TorreyII GottesmanDS McCray1999-07-22Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/111This item is in the repository with the URL: http://cogprints.org/id/eprint/1111999-07-22ZTemporal fluctuations in coherence of brain wavesAs a measure of dynamical structure, short term fluctuations of coherencebetween 0.3 and 100 Hz in the electroencephalogram (EEG) of humans were studied from recordings made by chronic subdural macroelectrodes 5-10 mm apart, on temporal, frontal and parietal lobes, and from intracranial probes deep in the temporal lobe, including the hippocampus, during sleep, alert and seizure states. The time series of coherence between adjacent sites calculated every second or less often varies widely in stability over time; sometimes it is stable for half a minute or more. Within two minute samples, coherence commonly fluctuates by a factor up to 2 or 3, in all bands, within the time scale of seconds to tens of seconds. The power spectrum of the time series of these fluctuations is broad, extending to 0.02 Hz or slower, and is weighted toward the slower frequencies; little power is faster than 0.5 Hz. Some records show conspicuous swings with a preferred duration of 5-15 s, either irregularly or quasi-rhythmically with a broad peak around 0.1 Hz. Periodicity is not statistically significant in most records. We have not found a consistent difference between lobes of the brain, subdural and depth electrodes or sleeping and waking states, in our sampling. Seizures generally raise the mean coherence in all frequencies and may reduce the fluctuations by a ceiling effect. The coherence time series of different bands is positively correlated (0.45 overall); significant non-independence extends for at least two octaves. Coherence fluctuations are quite local; the time series of adjacent electrodes is correlated with that of the nearest neighbor pairs (10 mm) to a coefficient averaging ca. 0.4, falling to ca. 0.2 for neighbors-but-one (20 mm) and to < 0.1 for neighbors-but-two (30 mm). The evidence indicates fine structure in time and space, a dynamic and local determination of this measure of cooperativity. Widely separated frequencies tending to fluctuate together exclude independent oscillators as the general or usual basis of the EEG, although a few rhythms are well known under special conditions. Broadband events may be the more usual generators. Loci only a few mm apart can fluctuate widely in seconds, either in parallel or independently. Scalp EEG coherence cannot be predicted from subdural or deep recordings, or vice versa and intracortical microelectrodes show still greater coherence fluctuation in space and time 1. Widely used computations of chaos and dimensionality, made upon data from scalp or even subdural or depth electrodes, even when reproducible in successive samples, cannot be considered representative of the brain or the given structure or brain state but only of the scale or view (receptive field) of the electrodes used. Relevant to the evolution of more complex brains, which is an outstanding fact of animal evolution, we believe measures of cooperativity are likely to be among the dynamic features by which major evolutionary grades of brains differ. In spite of a large literature on the electroencephalogram, we have an extremely limited picture of the structure of activity in the brain on the scales of millimeters and seconds. In spite of a prevailing view that the principal generators of the compound field potentials in the brain are microscopic, cellular or subcellular and chiefly membrane potentials, our extant data base is mainly scalp recordings on humans, usually 40 mm apart, each conservatively estimated to take the vector sum of activity in ca. 15 million cells, assuming a volume 1.5 mm deep x 10 x 10 mm tangentially at 50,000 neurons per cubic millimeter and an equal number of glia. In spite of an extensive knowledge of cellular interaction by synaptic mechanisms, our quantitative understanding of the amount of interaction by this route versus electrotonic or chemical field effects is almost nil. Under such circumstances, we consider quite vulnerable such concepts as synchronization, resonance, rhythmicity and independence of frequency components of the EEG - each an inference, but seldom measured. The present report is one of a series aiming at some insight into the fine structure in space and time of the dynamical signs provided in the compound field potentials, as recorded directly on or in the brain 1, 2, 3, 4, 5, 6, 7, 8, 9. The main goal is to test the hypothesis that one measure of cooperativity at each frequency, namely coherence, varies in time on the scale of seconds or fractions of a second, with evidence of more than stochastic structure and that the fluctuation is different for closely spaced loci. We will show in addition that a wide range of frequency components of the EEG tend to covary in coherence, contrary to the usual assumption of independent oscillators.T.H. BullockM.C. McCluneJ.Z. AchimowiczV.J. Iragui-MadozR.B. DuckrowS.S. Spencer2000-08-13Z2011-03-11T08:54:22Zhttp://cogprints.org/id/eprint/923This item is in the repository with the URL: http://cogprints.org/id/eprint/9232000-08-13ZWorlds apart: Pictorial semantics in the left and right cerebral hemispheresThe dominant view in neuropsychology fails to consider that the
hemispheric "functional division of labor" in terms of language versus
non-language reflects but one dimension of hemispheric differences.
That is, specialization of language in the left hemisphere and of
spatial orientation in the right represent only specific aspects of the
general underlying hemispheric meaning systems. Indeed, we have found
that there can be two full-blown meaning systems, one in the left and
one in the right, which can operate separately and simultaneously in
the normal brain.
~
Dahlia W. Zaidel1998-06-15Z2011-03-11T08:53:38Zhttp://cogprints.org/id/eprint/39This item is in the repository with the URL: http://cogprints.org/id/eprint/391998-06-15ZCallosal transmission time before and after partial commissurotomyInterhemispheric transmission time was measured in a patient before and after partial commissurotomy sparing the splenium of the corpus callosum. The transmission time was measured using a simple reaction time paradigm with unimanual responses to lateralized flashes at 4 and 8 degrees of eccentricity. Post-operative transfer time was longer than pre-operative transfer time at 8 degrees but not at 4 degrees of eccentricity. These data do not support the notion that the callosal transfer time is always faster through motor rather than visual fibers. They rather suggest that the callosal transfer time through visual fibers is longer than the callosal transfer time through motor fibers only for flashes at large eccentricities.M. IacoboniI. FriedE. Zaidel1999-11-10Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/123This item is in the repository with the URL: http://cogprints.org/id/eprint/1231999-11-10ZA Comparative Survey Of Oscillatory Brain Activity, especially gamma-band rhythms.Nature loves to oscillate. Ongoing oscillations of a wide range of periods are familiar in animals, for example circannual, circalunar and circadian, the so-called minute rhythms of Galambos and Makeig (1988), respiratory, cardiac, and EEG rhythms of delta, theta and alpha frequencies, ca. 40 Hz cerebral, 200 Hz cerebellar, and pacemakers of electric organ discharges in certain electric fish which run at 1000-2000 Hz, night and day. In addition many living systems - or parts of them - love to show event-related oscillation. The gamma band of frequencies is popular from invertebrates to mammals, especially for transient oscillations, such as event-related rhythms, which have recently come to prominence and have been called induced rhythms in a recent book of that title (Baar and Bullock 1992). The purpose of this paper is to shed some perspective on the topic of the symposium by surveying the literature for examples of event-related oscillations, particularly those in the gamma band. I ask, for each example, four kinds of questions. (i) Are the events with which they are related similar? (ii) Are they suggestive of a common meaning, or (iii) of a common mechanism. (iv) Are the dynamics of the oscillation basically common or diverse?Theodore H. BullockJerzy Z. Achimowicz1999-08-30Z2011-03-11T08:53:40Zhttp://cogprints.org/id/eprint/116This item is in the repository with the URL: http://cogprints.org/id/eprint/1161999-08-30ZDynamic properties of human visual evoked and omitted stimulus potentialsVisual evoked potentials (VEP) and omitted stimulus potentials (OSPs) are reexamined in scalp recordings from 19 healthy subjects. The principal finding is a distinction in form, latency and properties between OSPs in the conditioning stimulus range <2 Hz, used in previous human studies, and those in the range >5 Hz, used in previous studies of selected elasmobranchs, teleost fish and reptiles. We cannot find OSPs between 2 and 5 Hz. The high frequency ("fast,"ca. 6 to >40 Hz) and the low frequency ("slow," ca. 0.3-1.6 Hz) OSPs have different forms and latencies but both tend to a constant latency after the omission, over their frequency ranges, suggesting a temporally specific expectation. Fast OSPs (typically N120, P170-230 and later components including induced rhythms at 10-13 Hz) resemble an OFF effect, and require fixation but not attention to the ISI. Slow OSPs (usually P500-1100) require attention but not fixation; they are multimodal, unlike the fast OSPs. Based on cited data from fish and reptiles, fast OSPs probably arise in the retina, to be modified at each subsequent level. We have no evidence on the origin of slow OSPs. In both ranges not only large, diffuse flashes; but weak, virtual point sources (colored LEDs) meters away suffice. They are difficult to habituate. Both require very short conditioning periods. The transition from the single, rested VEP to the steady state response (SSR) at different frequencies is described. Around 8-15 Hz in most subjects larger SSRs suggest a resonance. Alternation between large and small SSR amplitude occurs around 4 Hz in some subjects and conditions of attention, and correlates with an illusion that the flash frequency is two Hz or is irregular. Jitter of the conditioning intervals greatly reduces the slow OSP but only slightly affects the fast OSP. Differences between scalp loci are described.T.H. BullockSacit KaramürselJerzy Z. AchimowiczMcClune Michael C.Baar-Eroglu Canan1999-09-23Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/118This item is in the repository with the URL: http://cogprints.org/id/eprint/1181999-09-23ZEvent-related potentials to omitted visual stimuli in a reptileVisual omitted stimulus potentials (OSPs) were recorded from awake pond turtles with arrays of 3-20 electrodes in the dorsal cortex (DC), dorsal ventricular ridge (DVR) and optic tectum. Since they are generally longer in duration than the interstimulus interval (ISI), the standard experiment is a short conditioning train of regular light or dark flashes (1-20 Hz) whose termination elicits the OSP. Tectal surface OSPs after trains >7 Hz have two major positive peaks, P120-140 and P220-250 after the due-time of the first omission; after <7 Hz down to the minimum of 1.5 Hz only the slower peak appears. Some deep tectal loci also have one to three 100 ms wide negative waves peaking at variable times from 200-1300 ms. Forebrain OSPs in DC and DVR are approximately 30 ms later and often include induced 17-25 Hz oscillations, not phase-locked and attenuated in averages. Both tectal and forebrain OSP main waves tend toward a constant latency after the due-time, over a wide range of ISIs, as though the system expects a stimulus on schedule. Jitter of ISI around the mean does not greatly reduce the OSP. At all loci higher conditioning rates cause the amplitudes of the steady state response (SSR) VEPs to decline and of the OSPs to increase. Some similarities and correlations of regional amplitude fluctuations between OSPs and VEPs are noted. The OSP dynamics are consistent with the hypothesis of a postinhibitory rebound of temporally specific VEP components increasingly inhibited with higher stimulation rates; much of this response is retinal but each higher brain level further modulates. OSPs in this reptile are similar to those known in fish and to the "high frequency" type in humans, quite distinct in properties from the "low frequency" OSPs. It will be important to look at the high frequency type in laboratory mammals to determine whether they are present in the midbrain and retina, as in fish and reptiles.James C. PrechtlTheodore H. Bullock2000-08-16Z2011-03-11T08:54:23Zhttp://cogprints.org/id/eprint/938This item is in the repository with the URL: http://cogprints.org/id/eprint/9382000-08-16ZMemory for faces in epileptic children before and after brain surgeryMemory for pairs of unfamiliar children's faces was investigated in 29 children and adolescents suffering from left (LTLE) or right (RTLE) temporal-lobe epilepsy, before and after temporal-lobe surgery. Both immediate and delayed memory were tested. Before surgery, RTLE subjects performed worse than either LTLE subjects or normal children. After surgery, RTLE subjects improved significantly. Overall (after surgery), there was no significant LTLE-RTLE difference, but on delayed memory, the RTLE group was worse than the LTLE group. The results suggest specialization for facial memory in the right hemisphere of young patients, as in adults, despite early brain damage. Elizabeth D. BeardsworthDahlia w. Zaidel2000-08-13Z2011-03-11T08:54:22Zhttp://cogprints.org/id/eprint/920This item is in the repository with the URL: http://cogprints.org/id/eprint/9202000-08-13ZA view of the world from a split-brain perspectiveThe extent to which observed behavior in the complete commissurotomy
patients is supported by only one hemisphere would depend on individual
differences interacting with a variety of factors such as genetics,
intelligence, and so on. The lesson imparted here is that there is
sufficient functional redundancy in the neocortex so that the capacity
to maintain a wide range of abilities is within the control of one
hemisphere. And, yet, as seen in what is missing in the patients'
behavior, one hemisphere is not quite enough. Nature seems to have
intended that the two hemispheres complement each other, that the full
range of human behavior be best accomplished through interaction
between the left and right hemispheres.Dahlia W. Zaidel2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5315This item is in the repository with the URL: http://cogprints.org/id/eprint/53152006-12-22ZCorrelation of severity of psychiatric patients' delusions with right hemispatial inattention (left-turning behavior)
Studies associate psychotic disorders with various forms of subtle inattention to the right hemispace (left-turning behavior). The authors examined the correlation between this dopamine-related sign and severity of delusions (presumably dopaminergic symptoms) in 20 psychotic patients. Delusions were significantly correlated with severity of left-turning bias, and this neurological sign accounted for 33% of the variance in severity of delusions.HS BrachaRL LivingstonJ ClothierBB LiningtonCN Karson1999-10-21Z2011-03-11T08:53:41Zhttp://cogprints.org/id/eprint/121This item is in the repository with the URL: http://cogprints.org/id/eprint/1211999-10-21ZInterval-specific event related potentials to omitted stimuli in the electrosensory pathway in elasmobranchs: an elementary form of expectationMultiunit activity and slow local field potentials show Omitted Stimulus Potentials (OSP) in the electrosensory system in rays after a missing stimulus in a 3 to >20 Hz train of microvolt pulses in the bath, at levels from the primary medullary nucleus to the telencephalon. A precursor can be seen in the afferent nerve. The OSP follows the due-time of the first omitted stimulus with a, usually, constant main peak latency, 30-50 ms in medullary dorsal nucleus, 60-100 ms in midbrain, 120-190 ms in telencephalon - as though the brain has an expectation specific to the interstimulus interval (ISI). The latency, form and components vary between nerve, medulla, midbrain and forebrain. They include early fast waves, later slow waves and labile induced rhythms. Responsive loci are quite local. Besides ISI, which exerts a strong influence, many factors affect the OSP slightly, including train parameters and intensity, duration and polarity of the single stimulus pulses. Jitter of ISI does not reduce the OSP substantially, if the last interval equals the mean; the mean and the last interval have the main effect on both amplitude and latency. Taken together with our recent findings on visually evoked OSPs, we conclude that OSPs do not require higher brain levels or even the complexities of the retina. They appear in primary sensory nuclei and are then modified at midbrain and telencephalic levels. We propose that the initial processes are partly in the receptors and partly in the first central relay including a rapid increase of some depressing influence contributed by each stimulus. This influence comes to an ISI-specific equilibrium with the excitatory influence; withholding a stimulus and hence its depressing influence causes a rebound excitation with a specific latency.T.H. BullockSacit KaramürselMichael H. Hofmann2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5316This item is in the repository with the URL: http://cogprints.org/id/eprint/53162006-12-22ZSecond-trimester markers of fetal size in schizophrenia: a study of monozygotic twinsOBJECTIVE: Since the second prenatal trimester is the critical period of massive neural cell migration to the cortex, and fingertip dermal cells migrate to form ridges during this same period, the authors sought to determine whether there are differences in fingertip ridge count in pairs of monozygotic twins discordant for schizophrenia, possibly indicating that a prenatal anatomical insult affected the twins differently. METHOD: The fingertip dermal ridges of 30 pairs of monozygotic twins (23 pairs in which the twins were discordant for schizophrenia and seven pairs in which both twins were normal) were counted by two persons trained in anthropometric research. Intrapair differences in the counts were then measured, and the differences among the pairs of normal twins were compared with the differences among the pairs discordant for schizophrenia. RESULTS: The twins discordant for schizophrenia had significantly greater absolute intrapair differences in total finger ridge count and significantly greater percent intrapair differences than the normal twins; i.e., their fingerprints were significantly less "twin-like." CONCLUSIONS: The study suggests that various second-trimester prenatal disturbances in the epigenesis of one twin in a pair discordant for schizophrenia may be related to the fact that only one of the twins expresses his or her genetic predisposition toward schizophrenia. This is consistent with a "two-strike" etiology of schizophrenia: a genetic diathesis plus a second-trimester environmental stressor.HS BrachaEF TorreyII GottesmanLB BigelowC Cunniff2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5317This item is in the repository with the URL: http://cogprints.org/id/eprint/53172006-12-22ZA monozygotic mirror-image twin pair with discordant psychiatric illnesses: a neuropsychiatric and neurodevelopmental evaluationOne piece of genetic evidence for the biological distinctness of schizophrenia and bipolar illness is the rarity of monozygotic twin pairs in which one twin suffers from schizophrenia and the other from bipolar disorder. The authors describe a pair of monozygotic mirror-image twins with discordant diagnoses, schizophrenia in one twin and bipolar or schizoaffective disorder in the other.LB LohrHS Bracha2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5318This item is in the repository with the URL: http://cogprints.org/id/eprint/53182006-12-22ZSubtle signs of prenatal maldevelopment of the hand ectoderm in schizophrenia: a preliminary monozygotic twin studyGenes that predispose to psychosis may act by making individuals more vulnerable to the disruptive effects of various prenatal insults. Fetal organogenesis is mostly completed in the first prenatal trimester. The second trimester is a critical period of massive neuronal migration from the periventricular germinal matrix to the cortex. A peripheral appendage developing simultaneously with this neural migration to the cortex is the distal upper limb. The ectodermal cells of the fetal upper limb migrate to form the hand skin during the fourth and fifth months of gestation (first two-thirds of the second prenatal trimester). Discrepancies in hand morphology between two identical (monozygotic [MZ]) co-twins may be temporal markers, that is, the "fossilized" evidence of various ischemic and other nongenetic insults that may have affected one fetus more than his MZ co-twin during that early part of the second trimester. In twins, prenatal insults (e.g., ischemia) frequently do not affect both co-twins to the same extent, so we examined seven putative markers of prenatal injury to the hand in 24 MZ twin pairs discordant for schizophrenia or delusional disorder. Compared with well co-twins, the affected co-twins had significantly higher total scores of fourth- and fifth-month dysmorphological hand anomalies.
HS BrachaEF TorreyLB BigelowJB LohrBB Linington2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5303This item is in the repository with the URL: http://cogprints.org/id/eprint/53032006-12-22ZEtiology of structural brain asymmetry in schizophrenia, an alternative hypothesisDuring normal development of the fetal brain, the left hemisphere lags behind the right hemisphere in intrauterine growth, causing the left hemisphere to be smaller than the right hemisphere throughout the early and mid-prenatal period. By the end of the second trimester, the right hemisphere has achieved almost full-term size; thus second-trimester injuries affecting neurons, that is, anoxic, ischemic, toxic, or infectious insults that are systemic and bilateral, will affect the left hemisphere more than the right hemisphere. While other explanations for brain asymmetries in schizophrenia have been proposed, the embryological literature is consistent with the hypothesis that a prenatal injury may be one etiological factor in producing the structural brain asymmetries seen in psychotic adult patients.
HS Bracha2006-12-22Z2011-03-11T08:56:44Zhttp://cogprints.org/id/eprint/5302This item is in the repository with the URL: http://cogprints.org/id/eprint/53022006-12-22ZAssymetric rotational (circling) behavior, a dopamine-related asymmetry, preliminary findings in unmedicated and never-medicated schizophrenic patientsCircling behavior is one of the best understood behaviors in animals. It is, for the most part, dopaminergically mediated and related to asymmetry in dopaminergic activity between the left and right basal ganglia or left and right frontal cortex. As a rule, animals rotate toward the hemisphere with lower striatal dopaminergic activity. A direct technique to find human analogs of circling behavior was not available. We have developed an automated rotometer with which we can apply the circling rodent model to humans. Left-prone circling behavior (neglect of right-sided turning) was found in 10 unmedicated schizophrenic patients, whereas 85 normal controls demonstrated almost equal right and left turning. These preliminary results may suggest the presence of a dopaminergic asymmetry in some unmedicated schizophrenic patients; that is, right anterior subcortical or cortical structures of the brain may manifest a relative dopaminergic overactivity compared to left anterior structures in at least some unmedicated patients with schizophrenia.HS Bracha2001-04-05Z2011-03-11T08:54:36Zhttp://cogprints.org/id/eprint/1390This item is in the repository with the URL: http://cogprints.org/id/eprint/13902001-04-05ZVentral tegmental (A10) system: neurobiology. 1. anatomy and connectivityIntroduction:
The VTA contains the A 10 group of dopamine (DA) containing neurons. These neurons have ben grouped into nuclei to be found on the floor of the midbrain tegmentum - the Nucleus paranigralis (Npn), Nucleus interfasicularis (Nif), Nucleus parabrachialis (Npbp) and the Nucleus linearis (rostralis and caudalis) *. The VTA is traversed by many blood vessels and nerve fibers **. Close to its poorly defined borders are found DA (A8, A9, A11) and 5-HT containing neurons (B8).
* Figures 2-4 show electron micrographs and drawings
** Figure 6 , electronmicrographs show neurovascular contacts in the rat and cat that could be used for, say, steroid hormone influence on neurotransmission.
Efferent projections of the VTA can be divided into 5 subsystems.
The mesorhombencephalic projects to other monoaminergic nucei, the cerebellum and a fine projection descends to other tegmental nuclei as far as the inferior olive. Fibers to the spinal cord havenot been demonstrated.
The mesodiencephalic path projects to several thalamic and hypothalamic nuclei andpossibly the median eminence. Functionally important examples are the anterior hypothalamic-preoptic area, Nucleus medialis dorsalis and reuniens thalami. These two subsystems are largely non-dopaminergic.
A minor mesostriatal projection is overshadowed by the large mesolimbic projection to the Nucleus accumbens, Tuberculum olfactorium, Septum lateralis and Nucleus interstitialis stria terminalis. There are also mesolimbic connections with several amygdaloid nuclei (especially centralis and basolateralis), the olfactory nuclei and Entorhinal cortex. A minor projection to the hippocampus has been detected.
The mesocortical pathway projects to sensory (e.g. visual) motor, limbic (e.g. retrosplenial) and polysensory association coretices (e.g. prefrontal). Prefrontal, orbitofrontal (insular) and cingulate cortices receive the most marked innervation from the VTA. A more widespread presence of DA in other cortices of rodents becomes progressively more evident in carnivores and primates.
Most but not all projections are unilateral (see Table VI for % crossed). Some neurons project to more than one area in mesodiencephalic, limbic and cortical systems. The majority of these fibers ascend in the medial forebrain bundle (MFB). Most areas receiving a projection from the VTA (DA or non-DA) project back to the VTA. The septo-hippocampal complex in particiular and the limbic system in general provide quantitatively much less feedback than other areas.
The role of the VTA as a mediator of dialogue with the fronto - striatal and limbic / extrapyramidal system is discussed under the theme of " circuit " systems (Figure 11, 12 & 13).
The large convergence of afferents to certain VTA projection areas (e.g., prefrontal, entorhinal cortices, lateral septum, central amygdala, habenula, and N. accumbens) is discussed under the theme of " convergence " systems (Figure 15 & 16).
Animal studies clearly demonstrate that the VTA in general, and its DA projections in particular are strategically organized to influence integrative neural function in diverse regions of the meso-, di- and telencephalon.
R.D. OadesG.M. Halliday2001-01-22Z2011-03-11T08:54:29Zhttp://cogprints.org/id/eprint/1247This item is in the repository with the URL: http://cogprints.org/id/eprint/12472001-01-22ZSelf recognition and social awareness in the deconnected minor hemisphereTwo patients with cerebral commissurotomy were tested with visual input lateralized to left or right half of the visual field by an opaque hemifield screen set in the focal plane of an optical system mounted on a scleral contact lens which allowed prolonged exposure and ocular scanning of complex visual arrays. Key personal and affect-laden stimuli along with items for assessing general social knowledgability were presented among neutral unknowns in visual arrays with 4-9 choices. Selective manual and associated emotional responses obtained from the minor hemisphere to pictures of subject's self, relatives, pets and belongings, and of public, historical and religious figures and personalities from the entertainment world revealed a characteristic social, political, personal and self-awareness comparable roughly to that of the major hemisphere of the same subject.Roger W. SperryEran ZaidelDahlia W. Zaidel1998-04-25Z2011-03-11T08:53:37Zhttp://cogprints.org/id/eprint/19This item is in the repository with the URL: http://cogprints.org/id/eprint/191998-04-25ZCerebral cortex neurons with extra spikes: a normal substrate for epileptic discharges?Double spikes during otherwise rhythmic discharge were frequently observed in 'fast' pyramidal tract neurons in response to steady depolarizing currents injected through the recording micropipette. The extra spike appears to arise from a large depolarizing afterpotential crossing the falling threshold several milliseconds following a spike; extra spikes themselves may generate further extra spikes in a similar manner, generating burst patterns which are strikingly similar to those of epileptic neurons.William H. CalvinGeorge W. Sypert1998-04-25Z2011-03-11T08:53:37Zhttp://cogprints.org/id/eprint/18This item is in the repository with the URL: http://cogprints.org/id/eprint/181998-04-25ZThree modes of repetitive firing and the role of threshold time course between spikes.When rhythmic firing is elicited in cat spinal motoneurons by long-lasting depolarizing currents, the 'threshold' voltage from which each spike arises may appear to be quite constant (Fig. 1A, arrow). If one probes for the threshold during the interspike interval (ISI), however, it is seen to fall well below this level, rising towards it later in the ISI. Exceptionally large depolarizing afterpotentials may intersect this threshold time course shortly after a spike, causing an extra spike. The extra spike itself may also similarly produce another extra spike; thus a regenerative cycle may produce a burst of spikes at a high firing rate.William H Calvin