TESTOSTERONE IS CORRELATED WITH REGIONAL MORPHOLOGY OF THE HUMAN CORPUS-CALLOSUM

Theoretical speculation in humans (S.F. Witelson, Psychoneuroendocrino logy 16 (1991) 131-153) and empirical findings in animals (R.H. Fitch, P.E. Cowell, L.M. Schrott, V.H. Denenberg, Int. J. Dev. Neurosci. 9 ( 1991) 35-38) suggest that testosterone (T) may play a significant role in the development of the corpus callosum (CC). However, there are cu rrently no empirical studies directly relating T concentrations to cal losal morphology in humans. The purpose of the present study was to in vestigate the relationship between free T concentrations as determined by radioimmunoassay, and the mid-sagittal area of the corpus callosum , as determined by magnetic resonance imaging (MRI). Subjects were 68 young adult (20-35 years), neurologically normal, right-handed males. All subjects underwent MRI and provided two samples of saliva for radi oimmunoassay of T and cortisol. Anatomical regions of interest include d total brain volume, left and right hemisphere volume and regional ar eas of the CC. CC regions were defined using two different measurement techniques, each dividing the CC into six sub-sections. Anatomical me asurements were performed blind with respect to the hormone levels of subjects. A significant positive correlation between T concentration a nd cross-sectional area of the posterior body of the CC was found. Thi s finding was consistent across the two measurement techniques and was not attributable to individual differences in total brain volume. All correlations between cortisol and CC sub-regions were non significant . The results of this study are consistent with the notion that T, at an earlier stage in development, may play a significant role in modula ting cortical/callosal architecture in humans. (C) 1997 Elsevier Scien ce B.V.