The Role of Right- and Left-Brain Weights in Cerebral Lateralization of Right- and Left-Pawed Male and Female Cats

Abstract

The contributions of right- and left-brain weights to the ratio of the left- to the right-brain weight (L/R) were studied in cats. Brain weight was expressed as the ratio of brain weight to body weight. The relative right- and left-brains in the right-pawed male cats were found to be heavier and more asymmetric (L/R < O) than those in the left-pawed male cats. Only in right-pawed males was the mean L/R ratio found to be significantly smaller than zero. The left-pawed males had smaller and more symmetric brains than the right-pawed males. There was no significant difference between L/R ratios in the right-pawed and left-pawed females. The mean L-R brain weight was found to be significantly smaller than zero in the right-pawed male and left-pawed female cats (no significant difference in other samples). The L/R ratio linearly increased as the relative right-brain weight decreased in the right-pawed and left-pawed males; the L/R ratio linearly increased as the right-brain weight and especially the left-brain weight increased in the right-pawed and left-pawed females. These results partly supported the testosterone hypothesis of cerebral lateralization. The results have also suggested that the right brain in males and the left brain in females would be the main factor determining cerebral lateralization in cats.

Key Words:

• Cerebral lateralization
• brain
• cat