Stress impedes exploration and the acquisition of spatial information in the eight-arm radial maze

Abstract

To determine whether stress impairs the acquisition of spatial information in the eight-arm radial maze, one group of rats (n = 8) was restrained and exposed to ninety 1-sec, 1-mA tailshocks. Twenty-four hours later, they were reexposed to 5 shocks, and 30 min later, they were tested on the radial maze with the use of obvious spatial cues. Compared with the unstressed controls (n = 8), the stressed rats displayed a significantly different distribution of errors across the 12 trials, an effect attributable, in part, to their initial decrease in exploration and increase in perseveration. An equation that controls for the changing probability of choices and errors during a trial is presented, and the calculations suggest that the stressed rats are capable of learning the maze, but that their baseline behavior hinders the process. Since both stress and long-term potentiation (LTP) increase classical conditioning and both delay the acquisition of spatial information, these results are consistent with the hypothesis that stress is inducing a phenomenon similar to, if not the same as, LTP. © 1992, Psychonomic Society, Inc.. All rights reserved.