Regional decreases of cortical choline acetyltransferase after lesions of the septal area and in the area of nucleus basalis magnocellularis.

Choline acetyltransferase and [3H]choline uptake have been measured in neocortical regions and hippocampus one week after lesions which destroyed the septum bilaterally, and after unilateral lesions in the area of nucleus basalis magnocellularis. Lesions of the septal area, which severely decreased choline acetyltransferase in hippocampus, only moderately decreased choline acetyltransferase in a posterior cortical region and had no effect in frontal and parietal regions. In contrast, lesions which included nucleus basalis magnocellularis decreased choline acetyltransferase markedly in frontal and parietal regions and had less of an effect in the posterior cortical regions. Lesion-induced decreases of [3H]choline uptake paralleled those of choline acetyltransferase. Lesion which included nucleus basalis magnocellularis had no effect on choline acetyltransferase in hippocampus, nucleus accumbens, olfactory tubercle, midbrain or pons-medulla. These results suggest that existence of topographically distinct cholinergic inputs to neocortex. In agreement with previous studies, cholinergic projections from the peripallidal region of nucleus basalis magnocellularis are predominantly to frontal and parietal neocortex. In contrast to previous suggestions, cholinergic projections to neocortex from the septal area are limited to the posterior regions of neocortex.