Relationships among weights of right and left cerebral hemispheres, and right minus left brain weight in right- and left-pawed male and female cats: importance of body weight.

Abstract

Interrelationships among the right- (R), left- (L) brain weights, R-L brain weight, and R + L brain weight were studied in adult cats. The raw brain weights and the brain weights relative to body weight (brain weight: body weight) were studied separately. The raw R-L brain weight showed no significant correlation with the raw R+L brain weight. The relative R-L brain weight was found to be positively linearly correlated with the R + L brain weight only in the right-pawed (RH) males. So, the asymmetry in relative brain weight increased with the relative total brain weight only in RH males, suggesting a common factor favoring an asymmetrical brain and an increased body weight (testosterone). The relative R- and L-brain weights were found to be inversely related to the relative R-L brain weight only in the RH female cats with R-L brain weight smaller than zero (testosterone in males, estrogen in females). It was concluded that hormonal factors influencing the body weight may also influence the asymmetrical brain development in cats.