Similarities between sylvian fissure asymmetries in cat brain and planum temporale asymmetries in human brain.

Galaburda et al. (1987) have suggested that asymmetry of planum temporale in men would result from an asymmetrical neuronal loss; symmetry would implicate a failure of asymmetrical cell loss. There are several reports indicating a similarity between men and animal in cerebral lateralization. In the present work, a morphological analysis was performed in sylvian fissure (SF) of cats. Asymmetry coefficients (AC) were distributed symmetrically and normally with a mean of zero. However, female cats exhibited a relatively stronger leftward asymmetry (left SF > right SF), and male cats a relatively stronger rightward asymmetry in SF. The results generally supported those of Galaburda and his coworkers. Deviations from their results depended mainly on paw preference. The similarity between human brain and animal brain was accentuated once more concerning cerebral lateralization. The results were not appropriate to conclude about the mechanisms of cerebral lateralization. Testosterone in males and estrogen in females were suggested to be the main hormones contributing to the emergence of cerebral lateralization.