Neonatal transection of the corpus callosum affects rotational side preference in adult Swiss mice

In order to test the hypothesis that the ontogenetic development of the corpus callosum (CC) contributes to the establishment of behavioral lateralization, the rotatory behavior in the free-swimming test was studied in male Swiss mice that were subjected to mid-sagittal transection of the CC during the first postnatal day. At adulthood, 16 Acallosal and 30 Sham-operated mice were submitted to 3 sessions of the free-swimming rotatory test (diameter of the recipient = 21 cm; session duration = 5 min; inter-test interval = 48 h). The number and direction of 30° turns were recorded. Our results indicate that transected animals became progressively more lateralized than Sham ones from the first to the third session. This difference between groups was explained mainly by the more pronounced reduction in turning activity to the non-preferred side along the sessions that was observed in Acallosal mice. Our results give further support to the hypothesis that the normal development of the CC is related to the establishment of brain asymmetries in general and behavioral lateralization in particular.