Energy expenditure, heart rate, and ambulation during shock-avoidance conditioning of heart rate increases and ambulation in freely-moving rats.

Abstract

ABSTRACTUsing shock‐avoidance procedures with equivalent reinforcement criteria and in a running wheel situation, one group of rats was reinforced for heart rate increases (HR group) and another group for running (Amb group). Throughout 5 Habituation sessions and 5 Conditioning sessions, each 2 hrs in duration, continuous recordings were made of heart rate (HR), ambulation (Amb), and oxygen consumption (OC). The groups did not differ in their mean levels of HR, Amb or OC during Habituation or during Conditioning, although the introduction of the contingencies did elicit significant increases in the mean levels of all three variables. Amb group subjects distributed their activity more effectively in relation to the experimental contingencies, resulting in 5/6 subjects acquiring successful avoidance behavior against only 2/5 subjects in the HR group. Examination of individual subjects in both groups indicated that learners all exhibited very similar behavior profiles regardless of the contingencies applied during conditioning, and the same was true of nonlearners. Accordingly the data were regrouped for learners and nonlearners and reanalyzed. These analyses revealed that nonlearners differed from learners in the nature of the relationships they displayed between variations in HR, OC and Amb during both the preconditioning (habituation) and conditioning phases of the experiment. These differences are discussed together with data derived from additional conditioning sessions in which autonomic blocking agents (Propranolol and Methyl Atropine) were administered to a subgroup of learners.