Precision and variability in postsynaptic target selection of inhibitory cells in the hippocampal CA3 region

A. I. Gulyas, R. Miles, N. Hajos, T. Freund

Research output: Contribution to journalArticle

175 Citations (Scopus)

Abstract

Non-pyramidal cells were filled intracellularly with biocytin in the CA3 region of the guinea-pig hippocampus in vitro, within or close to stratum pyramidale. On the basis of camera lucida reconstructions and electron microscopy, six different cell types with distinct laminar distribution of axon terminals could be distinguished. The axon of three axo-axonic cells, three typical basket cells, and atypical basket cells of two types arborized in the perisomatic and proximal dendritic region of CA3 pyramidal cells. Two cells with axons innervating the distal dendritic segments of pyramidal cells were also found; one terminated in stratum radiatum and the other in stratum lacunosum - moleculare. Electron microscopy demonstrated that symmetrical synapses were formed by the labelled boutons on axon initial segments, somata, and proximal or distal dendrites of mostly pyramidal neurons. Axo-axonic cells showed absolute target selectivity for axon initial segments, whereas for the other cells the distribution of contacted elements was determined by the laminar distribution of axon terminals. In two cases, where additional cells were labelled with biocytin, multiple (up to nine) light microscopically identified contacts (presumed synaptic contacts) were established by the interneurons on several pyramidal cells and on an axo-axonic cell. Our results show that a restricted set of inhibitory cells, with somata within or close to CA3 stratum pyramidale, possess variable patterns of axonal arborization. Various types of postsynaptic elements are contacted, but precision in selecting certain targets and ignoring others is maintained within a particular cell type and layer. In contrast to the diversity of axonal arbors the structure of the dendritic trees shows no consistent differences, suggesting that the cells may be activated by a similar set of afferents. It seems probable that the innervation of precise regions of postsynaptic pyramidal cells by different types of interneurons often in conjunction with particular excitatory afferents underlies functional differences in inhibitory synaptic actions.

Original languageEnglish
Pages (from-to)1729-1751
Number of pages23
JournalEuropean Journal of Neuroscience
Volume5
Issue number12
DOIs
Publication statusPublished - 1993

Fingerprint

Hippocampal CA3 Region
Pyramidal Cells
Presynaptic Terminals
Carisoprodol
Interneurons
Axons
Electron Microscopy
Dendrites

Keywords

  • Axon arborization
  • GABA
  • Guinea-pig
  • Inhibition
  • Interneurons
  • Non-pyramidal cells

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Precision and variability in postsynaptic target selection of inhibitory cells in the hippocampal CA3 region. / Gulyas, A. I.; Miles, R.; Hajos, N.; Freund, T.

In: European Journal of Neuroscience, Vol. 5, No. 12, 1993, p. 1729-1751.

Research output: Contribution to journalArticle

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