Interactions of ECS and a light-dark cycle on one-way avoidance learning in rats

Abstract

After 56 days on a light-dark cycle, male Sprague-Dawley rats, 90 to 120 days old, received either ECS or sham ECS 4 or 24 h prior to training during the light or the dark phase of the cycle in one-way active avoidance. These variables interacted significantly to affect both errors and trials to criterion; however, principal consideration is given the errors data. The ECS-4-Dark group had significantly greater mean errors than all other groups (15.5 error p<.005), except the Sham-ECS-24-Light group, and the ECS-24-Dark group had significantly fewer mean errors than five of the other seven groups (6.2 errors; p <.005). The findings were interpreted in terms of the evidence that ECS and light-dark cycles affect brain acetylcholine and Deutsch’s hypothesis (1971) that too much or too little ACh activity may impair retention; this has been shown by Davis (1972) to be applicable to acquisition of one-way avoidance.