Synaptic reorganization in the lateral geniculate nucleus of the adult cat following chronic decortication

J. Somogyi, J. Hámori, V. L. Silakov

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The corona radiata containing all geniculo-cortical and cortico-geniculate fibers was transected in adult cats. One year after the operation synaptic architecture of laminae A and A1 of the decorticated LGN was investigated utilizing electron-microscopy and Golgi-EM. It was found that synaptic glomeruli became embedded in heavily gliotic neuropile, which contained the dendrites of surviving relay cells in addition to retinal axons and interneuronal processes. In contrast to the intact LGN, where the relay cell dendrites are exclusively postsynaptic, many morphologically identified relay neuronal dendrites of the decorticated LGN also contained large, round synaptic vesicles associated with distinct presynaptic sites. In 60% of all glomeruli, the large presynaptic dendrites of relay neurons occupied a central position and were postsynaptic to retinal axons and interneuronal dendrites/axons, but were presynaptic to other relay dendrites or interneuronal dendritic profiles. Occasional dendro-dendritic synapses between relay cell processes could be observed in the extraglomerular neuropile. Relay cell presynaptic dendrites formed unequivocal Gray I-type synapses, in accordance with the supposed excitatory character of relay cell output. Since sprouting of extrinsic or intrinsic axons could not be observed after decortication, it is proposed that the partial synaptic reorganization of the LGN was primarily due to the compensatory "axonization" of relay cell dendrites. It is further suggested that the electrophysiologically demonstrated expansion of retinal receptive fields in the chronically decorticated LGN was accomplished by the formation of dendro-dendritic synapses between relay cells and interneurons.

Original languageEnglish
Pages (from-to)485-498
Number of pages14
JournalExperimental Brain Research
Volume54
Issue number3
DOIs
Publication statusPublished - Apr 1984

Fingerprint

Geniculate Bodies
Dendrites
Cats
Axons
Synapses
Neuropil
Synaptic Vesicles
Interneurons
Electron Microscopy
Neurons

Keywords

  • Adult cats
  • Golgi-electron microscopy
  • Lateral geniculate nucleus
  • Quantitative electron microscopy
  • Reactive synaptogenesis

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Synaptic reorganization in the lateral geniculate nucleus of the adult cat following chronic decortication. / Somogyi, J.; Hámori, J.; Silakov, V. L.

In: Experimental Brain Research, Vol. 54, No. 3, 04.1984, p. 485-498.

Research output: Contribution to journalArticle

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