Effects of social isolation and crowding upon active-avoidance performance in the rat

Male and female Sprague-Dawley rats reared in social isolation and in crowded conditions were tested on their active-avoidance performance. Only males appeared to be affected by the treatments; no housing-condition effect was found on the performance of females. The most severe housing-condition effect was that of social isolation; the isolated males showed impaired acquisition of the avoidance response. We have previously reported diminished adrenocortical flexibility in male isolates, which might account for the present results. A possible failure of the inhibition mechanisms of isolates is also taken into account.