INTACT SPATIAL-LEARNING FOLLOWING LESIONS OF BASAL FOREBRAIN CHOLINERGIC NEURONS

THE role of the basal forebrain cholinergic system in learning and mem ory has held considerable interest since the discovery of cholinergic neurodegeneration in the basal forebrain in Alzheimer's disease. Contr ary to expectation, selective removal of basal forebrain cholinergic n eurons projecting to either hippocampus or neocortex fails to impair l earning in a spatial task widely used to study hippocampal/cortical fu nction. If cholinergic neurons contribute to learning and memory by in tegrated regulation of hippocampal and cortical processing, combined r emoval of hippocampal and cortical cholinergic projections might be ne cessary to produce impairment. However, this combined lesion failed to impair spatial learning. These data argue against the vie cv that bas al forebrain cholinergic deficiency plays a prominent role in disorder s of learning and memory.