P. Nopoulos et al., Sexual dimorphism in the human brain: evaluation of tissue volume, tissue composition and surface anatomy using magnetic resonance imaging, PSYCH RES-N, 98(1), 2000, pp. 1-13
Magnetic resonance imaging (MRI) was used to evaluate sex differences in br
ain morphology by comparing measures of brain tissue volume, brain tissue c
omposition (proportions of gray and white matter), and measures of cortical
surface anatomy. A large and well-matched sample of healthy women (n = 42)
and healthy men (n = 42) were evaluated. There was a significant gender ef
fect on intracranial volume, males being larger. However, this increase in
size was limited to the cerebrum as there was no sex difference in the volu
me of the cerebellum. The gender difference in size of the cerebral volume
was evenly distributed, with all four lobes equally larger in males compare
d to females. Gray and white matter tissue proportions were similar between
the sexes globally. Regional tissue composition analysis showed sex differ
ences within the parietal lobes with females having proportionately more gr
ay matter on the right side. There were no differences between the sexes in
cortical surface anatomy measures. Overall, against the background of simi
larity in morphology, there are differences between the sexes with regard t
o general and regional brain measures. The functional significance of these
sex differences is unclear, but may represent the differential effects of
gonadal hormones during brain growth and development. (C) 2000 Elsevier Sci
ence Ireland Ltd. All rights reserved.