Figure 13.

Summary of shared neuron types and local circuit motifs of the lateral and medial entorhinal cortex. Because very little to nothing is known concerning Layer VI, no neurons and circuits are indicated. In Layer II, we show the two types of principal neurons, reelin (RE) and calbindin (CB) positive, and their specific local connectivity to parvalbumin (PV) and 5HT3a‐receptor (5H) expressing interneurons, respectively. Also shown are the main projections to hippocampal fields and intrinsic and commissural projections. Not included is the observation that these two populations of principal cells do communicate through a separate class of pyramidal neurons. In Layer III, about 40% of the neurons projecting to CA1 and subiculum do give rise to commissural collaterals. Pyramidal cells in Layer III show a relatively strong developed local excitatory network (not indicated). In Layer V, we indicate that VB neurons project to Va as well as to Layers II and III. Note that although data indicate that the superficially projecting Layer Vb neurons also project to Laver Va, conclusive evidence for that is still lacking, so we have depicted as if these respective projections originate from different principal neurons. Inputs to layers and identified neurons therein are not indicated since they differ between LEC and MEC. CA3, CA2, CA1 subfields of the hippocampus proper; CB, calbindin‐positive neuron; DG, dentate gyrus; EC, entorhinal cortex; LD, lamina dissecans; RE, reelin‐positive neuron [Color figure can be viewed at wileyonlinelibrary.com]