Impairment of memory and changes in neurotransmitters induced by basal forebrain lesion in rats

The effect of bilateral electrolytic lesioning of the anterior and posterior parts of the basal forebrain (BF) on learning behavior and changes in neurotransmitters in the central nervous system was investigated in rats. The posterior BF lesion caused more severe impairment than the anterior BF lesion in the acquisition of conditioned avoidance response in a two-way shuttle box. A severe deficit in acquisition of passive avoidance response was produced by the posterior BF lesion. Choline acetyltransferase (CAT) activity was decreased significantly in the parietal cortex but not in the occipital cortex in anterior BF-lesioned rats. However, it was not decreased in posterior BF-lesioned rats. The contents of monoamines in the hippocampus was decreased more significantly by the posterior BF lesion than by the anterior BF lesion. These results suggest that the impairment of memory in posterior BF-lesioned rats may be related mainly to monoaminergic function rather than to cholinergic deficit.