Lesion-induced dissociations between appetitive and consummatory grooming behaviors and their relationship to body weight and food intake rhythms.

Abstract

The behavior of oats with brain-stem lesions alternates between a normal state and a state characterized by the presence of elicitable groomiutf fragments. To specify possible rhythmic changes in physiological variable.- concomitant with the alternating behavioral states, body weight and food intake were monitored for a year in six normal and four brain-stem lesioned sats. Mathematical models were fitted to the body weight and food intake data, and statistical tests of the fits were made. Both normal and lesioned cats exhibited similar rhythms in body weight and food intake. The changes in behavioral state, present only in the lesioned group, were systematically related to the normal rhythm, with onsets of the abnormal behavioral state occurring on ascending or peak portions of the rhythm and reversions to normal on descending or trough portions of the rhythm. Cats with stereotaxic lesions of the brain stem spontaneously and repeatedly alter- . nate between two behavioral states, a normal grooming state and an abnormal grooming state (Randall, 1964; Randall & Lakso, 1968; Randall & Liittschwager, 1967) . In the abnormal state a dissociation of appetitive and consummatory grooming behavior occurs. The dissociation is detected by directing light tactile stimuli to the cat's body surface. When a normal cat's body surface is stimulated in this fashion (for example, when it is petted), orienting (appetitive) behaviors of the grooming repertoire or a social response of reciprocating the grooming favor may occur. In contrast to these normal behaviors, a cat with a brain-stem lesion may, when light tactile stimuli are directed to its body surface, exhibit only the consummatory grooming behaviors (the grooming scratch, lick, or bite). These consummatory behaviors occur alone, completely divorced from the normally preceding ap