Paw preference in mice with callosal defects induced by prenatal gamma irradiation.

The development of the corpus callosum of male Swiss mice was perturbed by exposure to gamma radiation at embryonic day 16 with total doses of 2 Gy (N = 48) or 3 Gy (N = 26). At adulthood paw preference was studied in these callosal defective animals and in 93 control nonirradiated male Swiss mice. The analysis of directional laterality indicated a populational tendency for right paw use in the 2 Gy group (60%) that was markedly increased in the 3 Gy group (95%). In the 3 Gy group, directional laterality was significantly different from chance in contrast to that observed in normal controls (49%). In the three groups most mice presented a significant individual paw preference. These data are consistent with our hypothesis that the early absence of the corpus callosum disrupts the normal pattern of directional asymmetries.