Selective Vulnerability of Neurons in Layer II of the Entorhinal Cortex during Aging and Alzheimer's Disease
Figure 1
Morphological and connectional heterogeneity among principal neurons in layer II of the medial and lateral entorhinal areas. (a) In the medial entorhinal cortex (MEC), stellate cells are the most numerous class of excitatory neuron in layer II. However, pyramidal neurons and horizontal tripolar cells also reside in layer II and send afferents to the hippocampus via the perforant pathway. Layer II neurons in the MEC receive input from the postrhinal cortex (POR), and to a lesser extent from the perirhinal cortex (PER), and also from the subiculum/parasubiculum (Sub/Parasub) of the hippocampus. Whether these inputs preferentially contact a particular morphological class of layer II neuron remains to be determined. (b) In the lateral entorhinal cortex (LEC), fan cells are the most frequently observed, but pyramidal and multiform neurons also contribute axonal input to the perforant pathway. Layer II neurons of the LEC receive strong input from the PER, weaker input from the POR, as well as from the Sub/Parasub region of the hippocampus proper. All connectivity information is based on a review by Van Strien and colleagues [14].
