YOUNG-ADULT HUMAN BRAIN - AN MRI-BASED MORPHOMETRIC ANALYSIS

Morphometric analysis was performed on three-dimensional MRI scans of 10 male and 10 female young adults with four principal objectives: (1) to characterize in vivo volumes of whole brain and substructures, (2) to explore volumetric symmetry in bilateral structures, (3) to consid er the extent to which volumetric measures are dimorphic in the male a nd female brain, and (4) to provide a normal volumetric database for t he young adult brain. Total brain volumes ranged between 1173 and 1626 cm(3). All bilateral structures were symmetric or nearly symmetric in volume, with the exception of a slightly larger right neocortex and a mygdala, and larger left lateral ventricle. Male brains were larger in volume than female brains, a difference that reached significance for cerebellar but not for cerebral hemisphere volume. In females, there was less cerebral white matter while caudate volume was larger than in the male brains. The proportions of caudate and hippocampus relative to total cerebral volumes were larger in females than in males. These four measures accurately predicted gender in 85% of the subjects by di scriminant analysis. No gender differences were noted in the structura l symmetry analysis. These results represent the first step in establi shing a comprehensive database of morphometric parameters, with unexpe cted findings relative to brain symmetry and sexual dimorphism.