Brain size and shape in strongly and weakly lateralized mice.

Mice from two selected lines differing markedly in their degree of lateralization, and from a random-bred control line, were studied. The brains of strongly lateralized mice were found to be heavier, and those of weakly lateralized mice to be lighter, than those of control mice of equivalent body weight; the degree of cerebral asymmetry was found to be least in weakly lateralized mice; and the corpora callosa of both selected lines were smaller than those of control mice. These findings are tentatively interpreted in terms of the effects of different behavioral strategies on the development of the central nervous system.