Autonomic and behavioral correlates of appetitive conditioning in rats.

The cardiac responses accompanying conditioned stimulus- (CS)-generated (orienting) and unconditioned stimulus- (US)-generated appetitively motivated behaviors (P. C. Holland, 1977) were investigated. On the basis of contemporary psychophysiological research, CS-generated responses were predicted to produce bradycardia, and US-generated responses to produce tachycardia. Pairing a 10-s visual CS with food delivery produced conditioned behavioral orienting (rearing) during the initial portion of the CS, followed by magazine approach (US-generated) responses as the CS progressed. CS onset produced a decrease in heart rate, mediated by an increase in parasympathetic stimulation of the heart, which persisted throughout the 10-s CS; no support for a biphasic cardiac response was observed. These data are discussed with respect to other conditioned autonomic responses and their relevance to foraging and food ingestion.