Hemispheric and gender-related differences in the gross morphology of the anterior cingulate/paracingulate cortex in normal volunteers: An MRI morphometric study

The sulci and gyri found within the anterior cingulate (AC), and across the cerebrum generally, have been found to vary in location and complexity fro m one individual to the next, making it difficult to analyze imaging data a ccurately and systematically. In this study, we examined the nature of morp hometric variance in the AC of the left and right cerebral hemispheres usin g high-resolution structural magnetic resonance imaging (MRI) acquired from 176 healthy volunteers. Depending on the presence of a paracingulate sulcu s (PCS) and its antero posterior extent, three types of AG patterns were id entified: 'prominent', 'present' and 'absent'. Hemispheric comparisons acro ss the whole sample showed the PCS to be more commonly 'prominent' in the l eft hemisphere and more commonly 'absent' in the right hemisphere. There wa s a significant gender difference, such that males showed an asymmetric pat tern characterized by increased fissurization of the left AC, while females showed greater symmetry, with less fissurization of the left AC. Overall c erebral morphology, namely hemispheric volume and hemispheric fissurization , were also measured and used as independent variables as well as covariate s in the analyses in order to ascertain the specificity of the results rega rding AC morphology. Results showed that cerebral volume for males was larg er on the right than on the left while fissurization showed the reverse asy mmetry of greater leftward fissurization. In contrast, females were symmetr ic in both respects. The findings regarding AC morphology could not be expl ained by differences in these overall cerebral measures or by differences i n age and handedness within the population. The results suggest that in the normal male brain, there exist morphological asymmetries at both the globa l and local levels that are less apparent in the female brain. The findings have implications for future studies examining the organization, develop m ent and functional anatomy of the AC.