Acquisition and retention of an active avoidance response to intense white noise: Kamin effect

Abstract

Three experiments were performed to investigate the acquisition and retention of an active avoidance response in rats to intense white noise. The results of Experiment 1 indicated that rats can acquire an active avoidance response to white noise. In Experiment 2 retention of avoidance performance was shown to be a U-shaped function of the retraining intervals (i.e., the Kamin effect) and escape latency performance was an inverted U-shaped function of the retraining intervals. This suggested that the Kamin effect may be mediated by stress-induced behavioral inhibition. The results of Experiment 3 demonstrated that scopolamine, an anticholinergic drug, alters the typical U-shaped avoidance function whereas methylscopolamine, an anticholinergic which produces the same peripheral effects as scopolamine but passes the blood-brain barrier poorly, does not. These results suggested that the underlying mechanism of the Kamin effect may be behavioral inhibition, mediated by stress-induced time-dependent changes in the CNS adrenergic-cholinergic system.