A review of problems inherent in the evaluation of the nonassociative effect of shock is presented. This is followed by a series of experiments intended to evaluate time-dependent changes in activity, reactivity (i.e., activity after reintroduction of the stressor) during intershock periods, and activity during shock itself, under conditions where associative influences are minimal. Regardless of whether initial training involved response-contingent or noncontingent shock, or whether shock was signaled or unsignaled, a U-shaped reactivity function was observed during the test, with lowest levels of activity occurring 1-4 hr after initial training. The U-shaped function was considerably less pronounced if shock was not delivered during the test. The form of the function varied somewhat depending on the presence or absence of a warning stimulus, as well as on whether shock was response dependent or independent. Moreover, the period of lowest reactivity varied as a function of the number of shocks administered during pretraining. Unlike the function seen during intershock periods, activity measured during shock was found to decline monotonically as the test-retest interval increased. Treatment with scopolamine or physostigmine eliminated both time-dependent changes, suggesting involvement of cholinergic mechanisms. Although chlorpromazine eliminated both functions, treatment with d-amphetamine produced several paradoxical effects, precluding definitive conclusions regarding catecholaminergic involvement in the time-dependent changes observed.

Behavioral Biology
Department of Psychology

Anisman, H. (1977). Time-dependent changes in activity, reactivity, and responsivity during shock: Effects of cholinergic and catecholaminergic manipulations. Behavioral Biology, 21(1), 1–31. doi:10.1016/S0091-6773(77)92215-5