Impairment of maze learning in rats by restricting environmental space

We previously reported that the restriction of environmental space attenuat es spontaneous locomotor activity and hippocampal acetylcholine release. To examine the effect of the restriction of environmental space on spatial le arning function, male rats were individually housed in a cylindrical large cage (diameter = 35 cm) or small cage (diameter = 19 cm) for 5 days. Eight- arm radial maze performance was examined to evaluate spatial learning and m emory functions. The task was performed once a day between 21:00 and 22:00 h in the dark phase. Although all rats learned and performed the task, thos e in the small cage had lower scores and took more trial time than those in the large cage. These results suggest that the restriction of environmenta l space impairs spatial learning in the dark phase in rats. (C) 2001 Elsevi er Science Ireland Ltd. All rights reserved.