ENVIRONMENTAL ENRICHMENT FOLLOWING BRAIN-DAMAGE - AN AID TO RECOVERY OR COMPENSATION

Postoperative environmental enrichment (EC) in rats with brain lesions has been hailed as a potential agent of recovery of function followin g brain damage. However, most such claims are based on examining the e ffects of EC on acquisition of a new task following brain injury. Else where we have argued that since this paradigm fails to establish a pre operative behavioural baseline against which to compare subsequent per formance it may demonstrate compensation but cannot provide evidence o f recovery. The present study directly addresses this issue by examini ng the effects of postoperative EC both on performance of a preoperati vely acquired water maze escape response as well as on de novo acquisi tion of such a response in rats with bilateral occipital and sham lesi ons. In terms of swim times postoperative EC was found to significantl y improve the performance of subjects which had not been preoperativel y trained but not the performance of those subjects which had. However , in terms of a trials to criterion measure postoperative EC benefitte d animals in both the preoperative and postoperative training conditio ns. The results, therefore, support the view that what has been observ ed in most previous studies is EC-induced compensation rather than rec overy and also help to define the conditions under which this occurs. However, they also argue for further investigation of the hypothesis t hat postoperative EC may enhance recovery of lesion-impaired performan ce consistency.