Innervation of cat visual areas 17 and 18 by physiologically identified X- and Y-type thalamic afferents. II. Identification of postsynaptic targets by GABA immunocytochemistry and Golgi impregnation

T. Freund, K. A C Martin, P. Somogyi, D. Whitteridge

Research output: Contribution to journalArticle

123 Citations (Scopus)

Abstract

The precise location of physiologically identified specific afferent input on the different types of cell in the visual cortex and the identification of the neurotransmitters of these cells are essential to a better understanding of the first stage of cortical processing. A combination of anatomical, neurochemical, and physiological methods was used to identify the cortical neurones that receive synaptic input from X- and Y-type afferents, which are thought to originate from cells of the lateral geniculate nucleus. One method relied on chance contacts made between single physiologically characterised axons, which had been injected with horseradish peroxidase (HRP), and the processes of cells impregnated by the Golgi method. These experiments revealed that both X and Y axons formed synapses on the dendrites of spiny stellate cells in layer 4. Y axons in both areas 17 and 18 established multiple synaptic contacts on basal dendrites of layer 3 pyramidal cells. One X axon contacted the apical dendrite of a layer 5 pyramidal cell and one Y axon contacted the dendrite of a large cell with smooth dendrites in layer 3. The maximum number of synapses made between one axon and a single postsynaptic cell was eight, although in most cases it was only one. It was concluded that one axon only provides a small fraction of the geniculate afferent input to an individual cell. A second method revealed that the somata in layer 4 in synaptic contact with the HRP-filled axon terminals were GABA-immunoreactive, and therefore might be involved in inhibitory processes. From light microscopic data it was found that somata receiving contacts from X axons in area 17 were significantly smaller (average diameter 15 μm) than those contacted by the Y axons in areas 17 and 18 (average diameter 24 μm). Somatic contacts were extremely rare in layer 6. These data show that the X and Y afferents may activate separate subsets of inhibitory neurones.

Original languageEnglish
Pages (from-to)275-291
Number of pages17
JournalJournal of Comparative Neurology
Volume242
Issue number2
Publication statusPublished - 1985

Fingerprint

gamma-Aminobutyric Acid
Axons
Cats
Immunohistochemistry
Dendrites
Pyramidal Cells
Carisoprodol
Horseradish Peroxidase
Synapses
Geniculate Bodies
Neurons
Presynaptic Terminals
Visual Cortex
Neurotransmitter Agents
Light

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

@article{97c3ed7a89994a42a3ce3b08c274befc,
title = "Innervation of cat visual areas 17 and 18 by physiologically identified X- and Y-type thalamic afferents. II. Identification of postsynaptic targets by GABA immunocytochemistry and Golgi impregnation",
abstract = "The precise location of physiologically identified specific afferent input on the different types of cell in the visual cortex and the identification of the neurotransmitters of these cells are essential to a better understanding of the first stage of cortical processing. A combination of anatomical, neurochemical, and physiological methods was used to identify the cortical neurones that receive synaptic input from X- and Y-type afferents, which are thought to originate from cells of the lateral geniculate nucleus. One method relied on chance contacts made between single physiologically characterised axons, which had been injected with horseradish peroxidase (HRP), and the processes of cells impregnated by the Golgi method. These experiments revealed that both X and Y axons formed synapses on the dendrites of spiny stellate cells in layer 4. Y axons in both areas 17 and 18 established multiple synaptic contacts on basal dendrites of layer 3 pyramidal cells. One X axon contacted the apical dendrite of a layer 5 pyramidal cell and one Y axon contacted the dendrite of a large cell with smooth dendrites in layer 3. The maximum number of synapses made between one axon and a single postsynaptic cell was eight, although in most cases it was only one. It was concluded that one axon only provides a small fraction of the geniculate afferent input to an individual cell. A second method revealed that the somata in layer 4 in synaptic contact with the HRP-filled axon terminals were GABA-immunoreactive, and therefore might be involved in inhibitory processes. From light microscopic data it was found that somata receiving contacts from X axons in area 17 were significantly smaller (average diameter 15 μm) than those contacted by the Y axons in areas 17 and 18 (average diameter 24 μm). Somatic contacts were extremely rare in layer 6. These data show that the X and Y afferents may activate separate subsets of inhibitory neurones.",
author = "T. Freund and Martin, {K. A C} and P. Somogyi and D. Whitteridge",
year = "1985",
language = "English",
volume = "242",
pages = "275--291",
journal = "Journal of Comparative Neurology",
issn = "0021-9967",
publisher = "Wiley-Liss Inc.",
number = "2",

}

TY - JOUR

T1 - Innervation of cat visual areas 17 and 18 by physiologically identified X- and Y-type thalamic afferents. II. Identification of postsynaptic targets by GABA immunocytochemistry and Golgi impregnation

AU - Freund, T.

AU - Martin, K. A C

AU - Somogyi, P.

AU - Whitteridge, D.

PY - 1985

Y1 - 1985

N2 - The precise location of physiologically identified specific afferent input on the different types of cell in the visual cortex and the identification of the neurotransmitters of these cells are essential to a better understanding of the first stage of cortical processing. A combination of anatomical, neurochemical, and physiological methods was used to identify the cortical neurones that receive synaptic input from X- and Y-type afferents, which are thought to originate from cells of the lateral geniculate nucleus. One method relied on chance contacts made between single physiologically characterised axons, which had been injected with horseradish peroxidase (HRP), and the processes of cells impregnated by the Golgi method. These experiments revealed that both X and Y axons formed synapses on the dendrites of spiny stellate cells in layer 4. Y axons in both areas 17 and 18 established multiple synaptic contacts on basal dendrites of layer 3 pyramidal cells. One X axon contacted the apical dendrite of a layer 5 pyramidal cell and one Y axon contacted the dendrite of a large cell with smooth dendrites in layer 3. The maximum number of synapses made between one axon and a single postsynaptic cell was eight, although in most cases it was only one. It was concluded that one axon only provides a small fraction of the geniculate afferent input to an individual cell. A second method revealed that the somata in layer 4 in synaptic contact with the HRP-filled axon terminals were GABA-immunoreactive, and therefore might be involved in inhibitory processes. From light microscopic data it was found that somata receiving contacts from X axons in area 17 were significantly smaller (average diameter 15 μm) than those contacted by the Y axons in areas 17 and 18 (average diameter 24 μm). Somatic contacts were extremely rare in layer 6. These data show that the X and Y afferents may activate separate subsets of inhibitory neurones.

AB - The precise location of physiologically identified specific afferent input on the different types of cell in the visual cortex and the identification of the neurotransmitters of these cells are essential to a better understanding of the first stage of cortical processing. A combination of anatomical, neurochemical, and physiological methods was used to identify the cortical neurones that receive synaptic input from X- and Y-type afferents, which are thought to originate from cells of the lateral geniculate nucleus. One method relied on chance contacts made between single physiologically characterised axons, which had been injected with horseradish peroxidase (HRP), and the processes of cells impregnated by the Golgi method. These experiments revealed that both X and Y axons formed synapses on the dendrites of spiny stellate cells in layer 4. Y axons in both areas 17 and 18 established multiple synaptic contacts on basal dendrites of layer 3 pyramidal cells. One X axon contacted the apical dendrite of a layer 5 pyramidal cell and one Y axon contacted the dendrite of a large cell with smooth dendrites in layer 3. The maximum number of synapses made between one axon and a single postsynaptic cell was eight, although in most cases it was only one. It was concluded that one axon only provides a small fraction of the geniculate afferent input to an individual cell. A second method revealed that the somata in layer 4 in synaptic contact with the HRP-filled axon terminals were GABA-immunoreactive, and therefore might be involved in inhibitory processes. From light microscopic data it was found that somata receiving contacts from X axons in area 17 were significantly smaller (average diameter 15 μm) than those contacted by the Y axons in areas 17 and 18 (average diameter 24 μm). Somatic contacts were extremely rare in layer 6. These data show that the X and Y afferents may activate separate subsets of inhibitory neurones.

UR - http://www.scopus.com/inward/record.url?scp=0022361721&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0022361721&partnerID=8YFLogxK

M3 - Article

VL - 242

SP - 275

EP - 291

JO - Journal of Comparative Neurology

JF - Journal of Comparative Neurology

SN - 0021-9967

IS - 2

ER -