Effects of Brain Bisection on Eye and Paw Preference in Cats

Abstract

The eye preferred for sighting and the limb preferred for precise prehension were determined for nine young male cats under several conditions of brain bisections. Cats appeared to be ambilateral with respect to sighting eye, but had relatively strong preference for one or the other paw. Animals with strong paw preference also showed resistance to change in performance of a visually-guided response, even under conditions in which the hemisphere controlling the paw was surgically disconnected from the hemisphere receiving the visual cue, suggesting the possibility of a subcortical site of visual-motor integration. These data argue against the existence of a unitary biologic dimension determining both peripheral response asymmetry and specialization of the hemispheres for visual processing. The findings in this study conflict with evidence obtained from similar behavioral observations of monkeys but are understandable in light of reported anatomical differences between the primate and feline motor systems. The cat’s resistance to change in paw preference when visual input is restricted to the “disconnected” hemisphere can be seen as a reflection of the prominence of indirect (and apparent absence of direct) cortico-spinal connections with the final common path.