The effects of total and partial callosal agenesis on the rotatory behavior of BALB/cCF mice.

We report a study on rotational behavior (free swim test) of 30 adult male mice of an inbred strain in which about 20% of the animals are born with callosal defects (the BALB/cCF strain). The experiment was designed to study the relationship between the development of the corpus callosum and the degree of lateralization in rotatory behavior. Most of the BALB/cCF mice (77%) were lateralized rotators. Although most animals with a normal callosal area presented individual asymmetry, there was no significant tendency for a populational asymmetry toward one side in this group. In contrast, 75% of the animals with abnormally small callosal areas were left rotators. These animals, therefore, presented not only individual asymmetry, but also a tendency for a populational asymmetry. It was concluded that disturbances in the development of the corpus callosum are related to the appearance of directional populational asymmetry in rotatory behavior.