Gender-Specific Left–Right Asymmetries in Human Visual Cortex

Abstract

The structural correlates of gender differences in visuospatial processing are essentially unknown. Our quantitative analysis of the cytoarchitecture of the human primary visual cortex [V1/Brodmann area 17 (BA17)], neighboring area V2 (BA18), and the cytoarchitectonic correlate of the motion-sensitive complex (V5/MTϩ/hOc5) shows that the visual areas are sexually dimorphic and that the type of dimorphism differs among the areas. Gender differences exist in the interhemispheric asymmetry of hOc5 volumes and in the righthemispheric volumetric ratio of hOc5 to BA17, an area that projects to V5/MTϩ/hOc5. Asymmetry was also observed in the surface area of hOc5 but not in its cortical thickness. The differences give males potentially more space in which to process additional information, a finding consistent with superior male processing in particular visuospatial tasks, such as mental rotation. Gender differences in hOc5 exist with similar volume fractions of cell bodies, implying that, overall, the visual neural circuitry is similar in males and females.

Cerebral Asymmetry: A Quantitative, Multifactorial, and Plastic Brain Phenotype

“…These dimorphisms are different among the areas. Such differences may potentially give males more space to process additional information, a finding which is consistent with better male processing in particular visuospatial tasks, such as mental rotation (Amunts et al, 2007). Interestingly, these gender differences in hOc5 exist even when there are comparable volume fractions of cell bodies in both genders, which indicates that, overall, the visual neural circuitry is similar in males and females (Amunts et al, 2007).…”

Parcellations and Connectivity Patterns in Human and Macaque Cerebral Cortex

“…3b; Van Essen et al 2012c). If the intervening regions contain areas that are similar or slightly smaller in average surface area, as suggested by architectonic analyses yet to be accurately surface-mapped (Amunts et al 2007), human cortex may contain 150-200 distinct areas in each hemisphere.…”

Gender differences in human cortical synaptic density

“…Because higher brain functions are related to the activity of the neocortex, many studies aimed at identifying possible structural correlations for cognitive gender differences have focused on the cerebral cortex, using a variety of anatomical and brain imaging techniques. At the macroscopic level, sexual dimorphism has been reported in the cortical volume of the Wernicke and Broca areas (6), as well as in the frontal and medial paralimbic cortices (7)(8)(9)(10), and in the thickness and density of the gray matter in the parietal lobes (for a review see ref. 10).…”