Extensive lesions of cholinergic basal forebrain neurons do not impair spatial working memory.

A recent study suggests that lesions to all major areas of the cholinergic basal forebrain in the rat (medial septum, horizontal limb of the diagonal band of Broca, and nucleus basalis magnocellularis) impair a spatial working memory task. However, this experiment used a surgical technique that may have damaged cerebellar Purkinje cells. The present study tested rats with highly selective lesions of cholinergic neurons in all major areas of the basal forebrain on a spatial working memory task in the radial arm maze. In postoperative testing, there were no significant differences between lesion and control groups in working memory, even with a delay period of 8 h, with the exception of a transient impairment during the first 2 d of postoperative testing at shorter delays (0 or 2 h). This finding corroborates other results that indicate that the cholinergic basal forebrain does not play a significant role in spatial working memory. Furthermore, it underscores the presence of intact memory functions after cholinergic basal forebrain damage, despite attentional impairments that follow these lesions, demonstrated in other task paradigms.