Delayed reinforcement of switch-off behavior and amygdaloid lesions in cats

Effects of amygdaloid lesions on the switch-off behavior (SOB) and behavioral changes induced by a delayed reinforcement (DR) for SOB were investigated in 12 cats. The DR consisted of putting a delay time of 1.6 or 2.4 sec between a plate-pushing response and the actual termination of hypothalamic stimulation, and it produced a marked prolongation of response time for SOB (delay phenomenon). Bilateral electrolytic lesions of the amygdala had only limited effects on the SOB and the delay phenomenon; they tended to enhance the prolongation of response time induced by DR in 6 cats and it was accompanied by mild prolongation of response time of subsequent immediate reinforcement trials. These effects were interpreted to be due to apparent attenuation of emotion-producing potency of the hypothalamic stimulation, induced by reduction of facilitatory environmental influences on it.