Food-motivated performance as a function of weight loss in hypothalamic hyperphagic rats

Abstract

Rats with bilateral ventromedial lesions of the hypothalamus were tested on a VI 1-min reinforcement schedule at 5%, 10%, 15%, and 20% weight loss, first at nonobese then at obese weight levels. During both test phases, rats with lesions of the ventromedial nucleus (VMN) did not differ significantly from the control Ss in response rates, which increased as a linear function of percentage weight loss. However, the VMN Ss’ response rates decreased significantly from the nonobese to the obese test phase.