Role of the corpus callosum in expression of behavioral asymmetries induced by a unilateral dopamine lesion of the substantia nigra in the rat

The present study examines the effects of sectioning the corpus callosum on the expression of asymmetric behaviors induced by a unilateral 6-hydroxydopamine (6-OHDA) lesion of the substantial nigra. Severing the corpus callosum eliminated the asymmetry in spontaneous investigation of edges in an open-field, without affecting total time of investigation. In contrast, callosotomy reduced the magnitude of externally cued turning, but failed to affect the directional distribution of responding. Moreover, it reduced the magnitude of apomorphine- but not amphetamine-induced turning. It is suggested that transcallosal communication is required for those behavioral asymmetries induced by a unilateral dopamine lesion which depend on head, rather than whole body movements.