The topographical and laminar organization of the presubiculum's projection to the ipsi- and contralateral entorhinal cortex in the guinea pig.

This is a detailed report of a previously described projection from the presubiculum to the entorhinal area (Shipley, '74). The terminal degeneration in the entorhinal area is specifically confined to the outer three layers of this cortex. The projection is topogtaphically organized and confined to dorsal and medial parts of the entorhinal area. A similarly organized projection courses via the dorsal psalterium (dorsal hippocampal commissure) to the contralateral entorhinal area. Thus each presubiculum has an organized terminal pathway to the entorhinal cortices of both hemispheres.