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Electrophysiological and morphological properties of neurons in layer 5 of the rat postrhinal cortex
Author(s) -
Sills Joseph B.,
Connors Barry W.,
Burwell Rebecca D.
Publication year - 2012
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.22026
Subject(s) - entorhinal cortex , neuroscience , neocortex , perirhinal cortex , pyramidal cell , bursting , hippocampal formation , electrophysiology , cortex (anatomy) , biocytin , hippocampus , biology , chemistry , temporal lobe , epilepsy
The postrhinal (POR) cortex of the rat is homologous to the parahippocampal cortex of the primate based on connections and other criteria. POR provides the major visual and visuospatial input to the hippocampal formation, both directly to CA1 and indirectly through connections with the medial entorhinal cortex. Although the cortical and hippocampal connections of the POR cortex are well described, the physiology of POR neurons has not been studied. Here, we examined theelectrical and morphological characteristics of layer 5 neurons from POR cortex of 14‐ to 16‐day‐old rats using an in vitro slice preparation. Neurons were subjectively classified as regular‐spiking (RS), fast‐spiking (FS), or low‐threshold spiking (LTS) based on their electrophysiological properties and similarities with neurons in other regions of neocortex. Cells stained with biocytin included pyramidal cells and interneurons with bitufted or multipolar dendritic patterns. Similarity analysis using only physiological data yielded three clusters that corresponded to FS, LTS, and RS classes. The cluster corresponding to the FS class was composed entirely of multipolar nonpyramidal cells, and the cluster corresponding to the RS class was composed entirely of pyramidal cells. The third cluster, corresponding to the LTS class, was heterogeneous and included both multipolar and bitufted dendritic arbors as well as one pyramidal cell. We did not observe any intrinsically bursting pyramidal cells, which is similar to entorhinal cortex but unlike perirhinal cortex. We conclude that POR includes at least two major classes of neocortical inhibitory interneurons, but has a functionally restricted cohort of pyramidal cells. © 2012 Wiley Periodicals, Inc.