Synaptology of the proximal segment of pyramidal cell basal dendrites

Pyramidal neurons are covered with dendritic spines, the main postsynaptic targets of excitatory (asymmetrical) synapses. However, the proximal portion of both the apical and basal dendrites is devoid of spines, suggesting a lack of excitatory inputs to this region. In the present study we used elec...

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Bibliographic Details
Published in:The European journal of neuroscience 2004-02, Vol.19 (3), p.771-776
Main Authors: Alonso-Nanclares, L., White, E. L., Elston, G. N., DeFelipe, J.
Format: Article
Language:English
Subjects:
Animals
cortical circuits
Dendrites - physiology
Dendrites - ultrastructure
Female
inhibitory synapses
Male
Microscopy, Electron - methods
Pyramidal Cells - physiology
Pyramidal Cells - ultrastructure
rat neocortex
Rats
Rats, Wistar
Somatosensory Cortex - cytology
Somatosensory Cortex - drug effects
Somatosensory Cortex - physiology
Synapses - physiology
Synapses - ultrastructure
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Summary:Pyramidal neurons are covered with dendritic spines, the main postsynaptic targets of excitatory (asymmetrical) synapses. However, the proximal portion of both the apical and basal dendrites is devoid of spines, suggesting a lack of excitatory inputs to this region. In the present study we used electron microscopy to analyse the proximal region of the basal dendrites of supra‐ and infragranular pyramidal cells to determine if this is the case. The proximal region of 80 basal dendrites sampled from the rat hindlimb representation in the primary somatosensory cortex was studied by electron microscopy. A total of 317 synapses were found within this region of the dendrites, all of which were of the symmetrical type. These results suggest that glutamate receptors, although present in the cytoplasm, are not involved in synaptic junctions in the proximal portion of the dendrites. These data further support the idea that inhibitory terminals exclusively innervate the proximal region of basal dendrites.
ISSN:0953-816X
1460-9568
DOI:10.1111/j.0953-816X.2003.03166.x