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Morphological characterization of rat entorhinal neurons in vivo: soma-dendritic structure and axonal domains

Morphological characterization of rat entorhinal neurons in vivo: soma-dendritic structure and... 221 84 84 1 1 K. Lingenhöhl D. M. Finch Brain Research Institute University of California 73-364 CHS 90024 Los Angeles CA USA Department of Neurology, Reed Neurological Research Center University of California 90024 Los Angeles CA USA Department of Animal Physiology University of Tübingen Auf der Morgenstelle 28 W-7400 Tübingen Federal Republic of Germany Brain Research Institute, 73-364 CHS, and Department of Neurology, Reed Neurological Research Center University of California 90024 Los Angeles CA USA Summary We used in vivo intracellular labeling with horseradish peroxidase in order to study the somadendritic morphology and axonal projections of rat entorhinal neurons. The cells responded to hippocampal stimulation with inhibitory postsynaptic potentials, and thus likely received direct or indirect hippocampal input. All cells ( n = 24) showed extensive dendritic domains that extended in some cases for more than 1 mm. The dendrites of layer II neurons were largely restricted to layers I and II or layers I–III, while the dendrites of deeper cells could extend through all cortical layers. Computed 3D rotations showed that the basilar dendrites of deep pyramids extended roughly parallel to the cortical layering, and that they were mostly confined to the layer containing the soma and layers immediately adjacent. Total dendritic lengths averaged 9.8 mm ± 3.8 (SD), and ranged from 5 mm to more than 18 mm. Axonal processes could be visualized in 21 cells. Most of these showed axonal branching within the entorhinal cortex, sometimes extensive. Efferent axonal domains were reconstructed in detail in 3 layer II stellate cells. All 3 projected axons across the subicular complex to the dentate gyrus. One of these cells showed an extensive net-like axonal domain that also projected to several other structures, including the hippocampus proper, subicular complex, and the amygdalo-piriform transition area. The axons of layer III and IV cells projected to the angular bundle, where they continued in a rostral direction. In contrast to the layer II, III and IV cells, no efferent axonal branches leaving the entorhinal cortex could be visualized in 5 layer V neurons. The data indicate that entorhinal neurons can integrate input from a considerable volume of entorhinal cortex by virtue of their extensive dendritic domains, and provide a further basis for specifying the layers in which cells receive synaptic input. The extensive axonal branching pattern seen in most of the cells would support divergent propagation of their activity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experimental Brain Research Springer Journals

Morphological characterization of rat entorhinal neurons in vivo: soma-dendritic structure and axonal domains

Lingenhöhl, K.; Finch, D.
Experimental Brain Research , Volume 84 (1) – Mar 1, 1991
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References (41)

Publisher
Springer Journals
Copyright
Copyright © 1991 by Springer-Verlag
Subject
Biomedicine; Neurosciences; Neurology
ISSN
0014-4819
eISSN
1432-1106
DOI
10.1007/BF00231762
Publisher site
See Article on Publisher Site

Abstract

221 84 84 1 1 K. Lingenhöhl D. M. Finch Brain Research Institute University of California 73-364 CHS 90024 Los Angeles CA USA Department of Neurology, Reed Neurological Research Center University of California 90024 Los Angeles CA USA Department of Animal Physiology University of Tübingen Auf der Morgenstelle 28 W-7400 Tübingen Federal Republic of Germany Brain Research Institute, 73-364 CHS, and Department of Neurology, Reed Neurological Research Center University of California 90024 Los Angeles CA USA Summary We used in vivo intracellular labeling with horseradish peroxidase in order to study the somadendritic morphology and axonal projections of rat entorhinal neurons. The cells responded to hippocampal stimulation with inhibitory postsynaptic potentials, and thus likely received direct or indirect hippocampal input. All cells ( n = 24) showed extensive dendritic domains that extended in some cases for more than 1 mm. The dendrites of layer II neurons were largely restricted to layers I and II or layers I–III, while the dendrites of deeper cells could extend through all cortical layers. Computed 3D rotations showed that the basilar dendrites of deep pyramids extended roughly parallel to the cortical layering, and that they were mostly confined to the layer containing the soma and layers immediately adjacent. Total dendritic lengths averaged 9.8 mm ± 3.8 (SD), and ranged from 5 mm to more than 18 mm. Axonal processes could be visualized in 21 cells. Most of these showed axonal branching within the entorhinal cortex, sometimes extensive. Efferent axonal domains were reconstructed in detail in 3 layer II stellate cells. All 3 projected axons across the subicular complex to the dentate gyrus. One of these cells showed an extensive net-like axonal domain that also projected to several other structures, including the hippocampus proper, subicular complex, and the amygdalo-piriform transition area. The axons of layer III and IV cells projected to the angular bundle, where they continued in a rostral direction. In contrast to the layer II, III and IV cells, no efferent axonal branches leaving the entorhinal cortex could be visualized in 5 layer V neurons. The data indicate that entorhinal neurons can integrate input from a considerable volume of entorhinal cortex by virtue of their extensive dendritic domains, and provide a further basis for specifying the layers in which cells receive synaptic input. The extensive axonal branching pattern seen in most of the cells would support divergent propagation of their activity.

Journal

Experimental Brain Research – Springer Journals

Published: Mar 1, 1991

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