The level of nitric oxide in the cortex correlates well with brain lateralization.

The correlation between nitric oxide (NO) levels in the cortices and brain lateralization was investigated via the paw preference test in which three groups of mice (left-pawed, ambidextrous and right pawed) were selected. Results showed that the right cortices had higher NO levels than the left cortices for both normal and lipopolysaccharide-treated mice. There were significant differences in NO levels in the right/left cortices depending on the behavioral lateralization as expressed by paw preference. Finally, individual levels of NO in the right/left cortices correlated well with individual paw preference scores. The relationship was parabolic. The results suggest a strong relationship between NO asymmetries as well as the direction and the intensity of behavioral lateralization.