Behavioural Brain Research, 31 (1988) 31-45 Elsevier BBR 00843 37 Environmental enrichment and recovery from a complex Go/No-Go reversal deficit in rats following large unilateral neocortical lesions F.D. Rose, P.A. Dell, S. Love and M.J. Davey Department of Psychology. University of London Goldsmiths’ College, London SE14 6NW (U.K.) (Received 12 June 1987) (Revised version received 11 March 1988) (Accepted 14 March 1988) Key words: Enriched/impoverished environment; Recovery; Compensation; Discrimination reversal; Hemidecorticate rat Postoperative environmental enrichment in brain-lesioned rats has been found to enhance performance in tasks in which a range of sensory cues can be utilized but not in tasks in which information from one particular sensory modality is essential to goal attainment. This has generally been construed as evidence of a role for environmental enrichment in facilitating compen- sation for sensory loss but not recovery of lost function per se. However, most published investigations have adopted an experimental design which fails to empirically separate the processes of recovery and compensation. The present investigation, by employing a unisensory task and using unilateral cortical lesions, thus markedly reducing the functional value of compensatory mechanisms in the mediation of postoperative behaviour, seeks to distinguish the contributions of these processes. The results show a sizeable hemidecorticate deficit on a visual operant Go/No-go reversal task but fail to provide clear evidence of any facilitation of functional recovery as a result of postoperative environmental enrichment. INTRODUCTION The intuitive notion that, following brain dam- age, residual function may be maximised by in- creased environmental stimulation is embodied within existing approaches to the treatment of neuropsychological disorders”-12. It has also been the subject of controlled experimental in- vestigation in laboratory animals3,4,‘3,‘6*26. How- ever, laboratory based studies have been some- what disappointing in terms of providing leads for those working in clinical situations. In part this is due to the failure of such studies to define precisely the nature of the influence environmental emich- ment may have on the way tasks are performed following brain injury. The most frequently encountered test paradigm within the experimental animal literature involves bilateral lesioning of the brain in the rat followed by a period of environmental enrichment or im- poverishment’s and, finally, an assessment of per- formance of the brain-damaged animals on a learning task. Generally, it has been found that environmental enrichment facilitates performance on tasks in which a range of sensory cues can be utilized6*8~18*21,27-30, but not on tasks in which information from one particular sensory modality is essential to goal attainment’*2. This has been construed as indicating a role for environmental enrichment in stimulating compensation for sen- sory loss but not in stimulating genuine recovery of lost functioni4. Correspondence: F.D. Rose, Department of Psychology, University of London Golsmiths’ College, London SE14 6NW, U.K. 0166-4328/88/$03.50 0 1988 Elsevier Science Publishers B.V. (Biomedical Division)