The distribution of septal projections to the hippocampus of the rat

Abstract Terminal degeneration following lesions of the medial septal nucleus or of the contralateral hippocampus was mapped and compared with the distribution of acetylcholinesterase in the hippocampal formation of the rat. Previously unreported septal projections were found in the supragranular region of the dentate gyrus, an area which is also the locus of a dense band of acetylcholinesterase. This correspondence provides further support for the hypothesis that the enzyme is located in the septal efferents. These findings are combined with those of earlier workers in a hypothetical model of septo‐hippocampal relationships.