Cholinergic mechanisms and alterations in behavioral suppression as factors producing time-dependent changes in avoidance performance.

Abstract

Studied 360 male hooded and Holtzman rats that received either one-way or shuttle-avoidance training at 1 of 4 retention intervals following exposure to signaled inescapable shock. Hooded rats exhibited a -shaped retention function in both tasks, while Holtzman rats demonstrated a curvilinear function only in the shuttle task. In Exp. II scopolamine improved and physostigmine disrupted shuttle-avoidance performance, and both altered the form of the retention curve in 300 male Holtzman rats. In the 1-way task physostigmine essentially produced a curve which approximates a -shaped retention function early in training. The data support a hypothesis based on activity changes, subserved by adrenergic-cholinergic mechanisms, as being involved in the production of the Kamin effect. (42 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)