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Patterns of synaptic input on corticocortical and corticothalamic cells in the cat visual cortex. I. The cell body
Author(s) -
Fariñas Isabel,
DeFelipe Javier
Publication year - 1991
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903040105
Subject(s) - biology , visual cortex , axon , neuroscience , thalamus , pyramidal cell , gabaergic , ultrastructure , immunocytochemistry , cortex (anatomy) , anatomy , lateral geniculate nucleus , electron microscope , cerebral cortex , inhibitory postsynaptic potential , hippocampal formation , endocrinology , physics , optics
Immunocytochemical and electron microscopic methods were used to examine the ultrastructure and synaptology of callosal and corticothalamic pyramidal cell somata in the cat visual cortex (area 17). Callosal and corticothalamic cells were labeled after injection of horseradish peroxidase (HRP) in the contralateral visual cortex or in the ipsilateral lateral geniculate nucleus. The synaptic relationship between each of the two populations of pyramidal cells and cells containing the inhibitory neurotransmitter γM‐aminobutyric acid (GABA) was examined at the light and electron microscope level using the combined techniques of retrograde transport of HRP and GABA immunocytochemistry. We found that callosal and corticothalamic cell somata have an ultrastructure and synaptology that distinguishes them from each other. Reconstructions from electron micrographs of serial sections revealed that the vast majority of synapses (89–96%) on the cell body of pyramidal cells were formed by GABAergic axon terminals, and that within each population of pyramidal cells there was variability in the number and density of axosomatic synapses. Callosal pyramidal cells received a greater number and higher density of axosomatic synapses than corticothalamic cells. These data suggest that callosal cells receive more inhibition than corticothalamic cells at the level of their somata.