The effect of electroconvulsive shock on a conditioned emotional response in the rhesus monkey.

Abstract

A series of four experiments were conducted with Rhesus monkeys in order to investigate previously reported attenuating effects of electroconvulsive shocks (ECS) upon a conditioned emotional response (CER) of the ‘fear’ or ‘anxiety’ type. The fourth experiment in this series investigated the cardiovascular changes associated with the CER procedure and the effects of ECS upon such cardiovascular functions.The results of Expt. I identified the previously reported attenuating effect of ECS upon the CER and confirmed the transient nature of this effect. Expt. II failed to confirm the protective effect of ‘prophylactic’ ECS treatments in preventing the reappearance of the CER 20 days after completion of an intensive ECS treatment series. There were, however, important variations in procedure to which this outcome may be attributable. Similarly, procedural variations may account for the only partial replication in Expt. III of the previously reported reduction in the effectiveness of delayed ECS in attenuating the CER. Finally, Expt. IV demonstrated that the cardiovascular changes (significant reductions in heart rate and blood pressure) which accompany the behavioural changes observed during the CER are also markedly attenuated as a result of the ECS treatments.