Behavioral effects of differential postoperative housing after septal lesions made in weanling rats

Abstract

Male weanling rats that received septal lesions or control operations were subsequently housed for 40 days in an enriched condition or in social isolation to allow us to evaluate the contribution of postoperative environment to recovery of behavioral function. Septal lesions produced increased ambulation, reduced rearing in an open field (initially), impaired spontaneous alternation, and impaired performance in an eight-arm radial maze. Enrichment of the postoperative environment failed to facilitate behavioral recovery of any of these lesion-induced effects. Enriched-septal rats showed a relatively greater deficit during radial arm maze testing than did isolated-septal rats. Enriched-intact rats, on the other hand, outperformed isolated-intact rats on the radial arm maze. The behavioral deficits caused by septal lesions thus resemble some of the deficits produced by fimbria-fornix and entorhinal cortex lesions, in that they are not ameliorated by postoperative enrichment. These results contrast those of previous experiments using rats with dorsal hippocampus lesions.