?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Testosterone+and+grasp-reflex+differences+in+human+neonates&rft.creator=Tan%2C+Uner&rft.creator=Tan%2C+Meliha&rft.subject=Neuroendocrinology&rft.subject=Neuropsychology&rft.description=According+to+the+Geschwind-Behan-Galaburda+(GBG)+hypothesis%2C+prenatal+testosterone+(T)+causes+a+slowing+in+the+development+of+the+left+brain+with+a+consequent+compensatory+growth+in+the+right+brain%2C+creating+a+reverse+organisation+of+the+cerebral+lateralisation.+That+is%2C+left-+and+right-handedness+might+be+associated+with+high+and+low+prenatal+T+levels%2C+respectively.+To+test+this%0Ahypothesis%2C+the+relations+of+T+levels+(umbilical+cord+blood)+to+grasp-reflex+strengths+were+studied+in+human+neonates.+Handedness+was+assessed+by+measuring%0Athe+grasp-reflex+strengths+from+the+right+and+left+hands+in+10+trials+from+each+hand+alternatively.+There+were+two+handedness+groups%3A+right-handers+(R-L+significantly%0Agreater+than+zero)+and+left-handers+(significantly+smaller+than+zero).+Contrary+to+the+GBG+model%2C+the+mean+free+T+concentration+was+found+to+be+significantly+higher+in%0Aright-handers+than+left-handers+for+males+and+females.+There+was+no+significant+difference+in+the+total+T+levels+between+right-+and+left-handers.+Free+T+concentrations+positively+correlated+with+R-L+grasp-reflex+strengths%2C+i.e.+right-handedness+increased+as+T+increased%2C+and+left-handedness+increased+as+T+decreased.+Contrary+to+these+positive+correlations%2C+T+negatively+correlated+with%0Athe+grasp-reflex+strengths+from+the+right+and+left+hands.+These+results+partly+supported+the+GBG+hypothesis+for+this+spinal-motor-asymmetry+model.+Total+T+did+not+significantly+correlate+with+grasp-reflex+strengths.+The+results+suggest+that+prenatal+T+may+at+least+play+a+role+in+prenatal+determination+of+spinal+motor+lateralisation%2C+with+a+possible+consequent+upward+regulation+of+cerebral%0Alateralisation.%0A&rft.publisher=Taylor+%26+Francis&rft.contributor=Coraballis%2C+Michael&rft.contributor=McManus%2C+Chris&rft.contributor=Peters%2C+Michael&rft.date=2001&rft.type=Journal+(Paginated)&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F1439%2F2%2FTANTANLAT.PDF&rft.identifier=++Tan%2C+Uner+and+Tan%2C+Meliha++(2001)+Testosterone+and+grasp-reflex+differences+in+human+neonates.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F1439%2F