Sexual dimorphism of the human corpus callosum: Digital morphometric study

Correlation between corpus callosum sub-segmental area and cognitive processes in school-age children

We assessed the relationship between structural characteristics (area) and microstructure (apparent diffusion coefficient; ADC) of the corpus callosum (CC) in 57 healthy children aged 7.0 to 9.1 years, with diverse cognitive and academic abilities as well as executive functions evaluated with a neuropsychological battery for children. The CC was manually delineated and sub-segmented into six regions, and their ADC and area were measured. There were no significant differences between genders in the callosal region area or in ADC. The CC area and ADC, mainly of anterior regions, correlated with different cognitive abilities for each gender. Our results suggest that the relationship between cognitive abilities and CC characteristics is different between girls and boys and between the anterior and posterior regions of the CC. Furthermore, these findings strenghten the idea that regardless of the different interhemispheric connectivity schemes per gender, the results of cognitive tasks are very similar for girls and boys throughout childhood.

[Digital morphometric study of the extrasulcal surface of the cingulate gyrus in man]

INTRODUCTION

The frequency of different morphological types and extrasulcal (visible) surface area of the cingulate gyrus, were measured and analysed in order to obtain more precise data about morphology, right/left and sex differences in the human brain.

MATERIAL AND METHODS

The study included 42 brains (84 hemispheres) from persons of both sexes and of different age (26 males, 16 females, 20-65 years old), without neuropathological changes. After fixation in 10% formaline (3-4 weeks) and removal of meninges the brains were photographed under standard conditions by digital camera. Following determination of morphological type, regions of interest of cingulate gyrus were determined in stereotactic system system of coordinates and the extrasulcal surface was measured by digital AutoCAD planimetry.

RESULTS AND DISCUSSION

Three basic morphological types of cingulate gyrus were found: the continuous type (34.5%), segmented type (35.7%) and double paralel type (29.8%). There was no statistically significant difference in the frequency of morphological types related to the side (right/left) or sex (p 0.05). The area of extrasulcal cortex of cingulate gyrus was statistically significantly (p < 0.05) larger on the left hemispheres (for 1.13 cm) than on the right (left: 14.58 cm; right: 13.45 cnm. 7he extrasulcal surface of the left cingulate gyrus was significantly larger (p 0 .05) in males (males 15.9 cm; females - 13.6 cm), while for the right cingulate gyrus this difference was not significant.

CONCLUSION

Morphometry indicated sex and right/left differences of extrasulcal surface area of the human cingulate gyrus. However, the morphological analysis itself did not indicate corresponding differences, suggesting complexity of the problem of sex dimorphism and of right/left asymmetries in the domain of limbic cortex.

Asymmetry and sexual dimorphism of the medial frontal gyrus visible surface in humans

Background/Aim. Studies of visible (extrasulcal) surface of the brain hemispheres are not feasible for measurements of the brain size, but are valuable for analysis and quantification of sexual dimorphism and/or asymmetries of the human brain. Morphological and morphometric investigations of the brain may contribute in genetic studies of the human nervous system. The aim of this study was to determine and to quantify sexual dimorphism and the right/left morphological asymmetry of the visible surface of medial frontal gyrus (gyrus frontalis medialis - GFM). Methods. Measurements and analysis of the visible surface of GFM were done on 84 hemispheres (42 brains from the persons of both sexes: 26 males and 16 females, 20-65 years of age). After fixation in 10% formalin and dissection, digital morphometric measurements were performed. We studied these in relation to the side of the hemisphere and the person's sex. Standardized digital AutoCAD planimetry of the visible surface of GFM was enabled by the use of coordinate system of intercommissural line. Results. In the whole sample, the visible surface of the right GFM (21.39 cm2) was statistically significantly greater (p < 0.05) than the left GFM (18.35 cm2) indicating the right/left asymmetry of the visible surface of GFM. Also, the visible surface of the right GFM in the males (22.66 cm2) was significantly greater (p < 0.05) than in the females (19.35 cm2), while the difference in size of the left GFM between the males and the females was not significant (p > 0.05). Conclusion. Morphological analysis of visible surface of GFM performed by digital planimetry showed sexual dimorphism of the visible surface and the presence of right/left asymmetry of GFM.