Morphology, Electrophysiology and Functional Input Connectivity of Pyramidal Neurons Characterizes a Genuine Layer Va in the Primary Somatosensory Cortex

Cortical layer V classically has been subdivided into sublayers Va and Vb on cytoarchitectonic grounds. In the analysis of cortical microcircuits, however, layer Va has largely been ignored. The purpose of this study was to investigate pyramidal neurons of layer Va in view of their potential role in...

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Bibliographic Details
Published in:Cerebral cortex (New York, N.Y. 1991) N.Y. 1991), 2006-02, Vol.16 (2), p.223-236
Main Authors: Schubert, D., Kötter, R., Luhmann, H.J., Staiger, J.F.
Format: Article
Language:English
Subjects:
Animals
Barrel cortex
Brain Mapping
caged glutamate
functional connectivity
intracortical
Male
Nerve Net - cytology
Nerve Net - physiology
Neural Pathways - cytology
Neural Pathways - physiology
photolysis
Pyramidal Cells - cytology
Pyramidal Cells - physiology
Rats
Rats, Wistar
Somatosensory Cortex - cytology
Somatosensory Cortex - physiology
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Summary:Cortical layer V classically has been subdivided into sublayers Va and Vb on cytoarchitectonic grounds. In the analysis of cortical microcircuits, however, layer Va has largely been ignored. The purpose of this study was to investigate pyramidal neurons of layer Va in view of their potential role in integrating information from lemniscal and paralemniscal sources. For this we combined detailed electrophysiological and morphological characterization with mapping of intracortical functional connectivity by caged glutamate photolysis in layer Va of rat barrel cortex in vitro. Electrophysiological characterization revealed pyramidal cells of the regular spiking as well as the intrinsically burst firing type. However, all layer Va pyramidal neurons displayed uniform morphological properties and comparable functional input connectivity patterns. They received most of their excitatory and inhibitory inputs from intracolumnar sources, especially from layer Va itself, but also from layer IV. Those two layers were also the main origin for transcolumnar excitatory inputs. Layer Va pyramidal neurons thus may predominantly integrate information intralaminarly as well as from layer IV. The functional connectivity maps clearly distinguish layer Va from layer Vb pyramidal cells, and suggest that layer Va plays a unique role in intracortical processing of sensory information.
ISSN:1047-3211
1460-2199
DOI:10.1093/cercor/bhi100