Asymmetric distribution of side preference in hamsters can be reversed by lesions of the caudate nucleus.

Side preferences were tested in Syrian hamsters (Mesocricetus auratus) by placing them on an elevated centerboard which divided a rectangular arena in two equal compartments. When descending from the centerboard all animals turned more often right (79%) than left (21%). After small electrolytic lesions of the left caudate nucleus the side preference was reversed: 31% to the right and 69% to the left. Combined lesions of the left caudate nucleus and left sensorimotor cortex showed similar results; lesions of the left cortex alone had only minor effects. These observations support the hypothesis [28] that side preferences depend on asymmetries of the nigrostriatal system.