Cholinergic neurons from different subdivisions of the basal forebrain lack connectional specificity for cerebral cortical target sites in vitro.

Basal forebrain cholinergic neurons send their axons to cerebral cortex in a topographically organized projection. Experiments tested the hypothesis that this topographic organization results from target preferences of the cholinergic neurons. Slices containing either medial septum or substantia innominata were grown in co-culture with slices of lateral neocortex and hippocampus. Cholinergic neurons from septum and from substantia innominata projected axons into neocortex and hippocampus, without obvious differences in pattern or density. These data suggest that basal forebrain cholinergic neurons can innervate any portion of the cerebral mantle.