<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Testosterone and grasp-reflex differences in human neonates"^^ . "According to the Geschwind-Behan-Galaburda (GBG) hypothesis, prenatal testosterone (T) causes a slowing in the development of the left brain with a consequent compensatory growth in the right brain, creating a reverse organisation of the cerebral lateralisation. That is, left- and right-handedness might be associated with high and low prenatal T levels, respectively. To test this\nhypothesis, the relations of T levels (umbilical cord blood) to grasp-reflex strengths were studied in human neonates. Handedness was assessed by measuring\nthe grasp-reflex strengths from the right and left hands in 10 trials from each hand alternatively. There were two handedness groups: right-handers (R-L significantly\ngreater than zero) and left-handers (significantly smaller than zero). Contrary to the GBG model, the mean free T concentration was found to be significantly higher in\nright-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, i.e. right-handedness increased as T increased, and left-handedness increased as T decreased. Contrary to these positive correlations, T negatively correlated with\nthe 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, with a possible consequent upward regulation of cerebral\nlateralisation.\n"^^ . "2001" . . "6" . "2" . . "Taylor & Francis"^^ . . . " Laterality"^^ . . . . . . . . . . . . . . . . . . . . "Michael"^^ . "Peters"^^ . "Michael Peters"^^ . . "Meliha"^^ . "Tan"^^ . "Meliha Tan"^^ . . "Uner"^^ . "Tan"^^ . "Uner Tan"^^ . . "Chris"^^ . "McManus"^^ . "Chris McManus"^^ . . "Michael"^^ . "Coraballis"^^ . "Michael Coraballis"^^ . . . . . . "Testosterone and grasp-reflex differences in human neonates (PDF)"^^ . . . . . . "TANTANLAT.PDF"^^ . . "HTML Summary of #1439 \n\nTestosterone and grasp-reflex differences in human neonates\n\n" . "text/html" . . . "Neuroendocrinology" . . . "Neuropsychology" . .