Volumetric asymmetry in the human striate cortex.

A sample of 31 serially sectioned human brains, in age from 33 weeks of gestation through 94 years, was examined for volumetric asymmetries in the striate cortex. The right striate cortex was found to be larger than the left in 24 of 31 cases. On the average, the right striate cortex was larger than the left by about 5%; this difference was statistically significant. Although past studies indicated that the posterior cerebrum is anatomically asymmetrical, no consistent pattern had been found, and no study had examined the actual volume of the striate cortex in the two hemispheres. The demonstration of asymmetries in the striate cortex is important because differences exist between the hemispheres in a wide range of perceptual and spatial skills related to vision. I suggest that the striate cortical asymmetry is related to the right hemisphere's superiority in visuospatial functioning.