GABAergic neurons in the entorhinal cortex project to the hippocampus.

Among the entorhinal neurons that give rise to the perforant path, a small population is sparsely spinous and displays either a multipolar or a horizontal-bipolar dendritic tree. By application of post-embedding immunocytochemistry to neurons of these types with previously identified projections to the hippocampus we found immunoreactivity for gamma-aminobutyric acid (GABA). Thus, it appears that the perforant path not only contains an excitatory but also a small inhibitory component.