Unusual target selectivity of perisomatic inhibitory cells in the hilar region of the rat hippocampus

L. Acsády, I. Katona, Francisco J. Martínez-Guijarro, Gyórgy Buzsáki, T. Freund

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

Perisomatic inhibitory innervation of all neuron types profoundly affects their firing characteristics and vulnerability. In this study we examined the postsynaptic targets of perisomatic inhibitory cells in the hilar region of the dentate gyrus where the proportion of potential target cells (excitatory mossy cells and inhibitory interneurons) is approximately equal. Both cholecystokinin (CCK)- and parvalbumin-immunoreactive basket cells formed multiple contacts on the somata and proximal dendrites of mossy cells. Unexpectedly, however, perisomatic inhibitory terminals arriving from these cell types largely ignored hilar GABAergic cell populations. Eighty-ninety percent of various GABAergic neurons including other CCK-containing basket cells received no input from CCK-positive terminals. Parvalbumin-containing cells sometimes innervated each other but avoided 75% of other GABAergic cells. Overall, a single mossy cell received 40 times more CCK-immunoreactive terminals and 15 times more parvalbumin-positive terminals onto its soma than the cell body of an average hilar GABAergic cell. In contrast to the pronounced target selectivity in the hilar region, CCK- and parvalbumin-positive neurons innervated each other via collaterals in stratum granulosum and moleculare. Our observations indicate that the inhibitory control in the hilar region is qualitatively different from other cortical areas at both the network level and the level of single neurons. The paucity of perisomatic innervation of hilar interneurons should have profound consequences on their action potential generation and on their ensemble behavior. These findings may help explain the unique physiological patterns observed in the hilus and the selective vulnerability of the hilar cell population in various pathophysiological conditions.

Original languageEnglish
Pages (from-to)6907-6919
Number of pages13
JournalJournal of Neuroscience
Volume20
Issue number18
Publication statusPublished - Sep 15 2000

Fingerprint

Hippocampus
Cholecystokinin
Parvalbumins
Carisoprodol
Interneurons
Neurons
GABAergic Neurons
Dentate Gyrus
Dendrites
Population
Action Potentials

Keywords

  • Basket cell
  • Dentate gyrus
  • Hilus
  • Hippocampus
  • Inhibition
  • Interneuron
  • Mossy cell
  • Mossy fiber
  • Perisomatic

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Unusual target selectivity of perisomatic inhibitory cells in the hilar region of the rat hippocampus. / Acsády, L.; Katona, I.; Martínez-Guijarro, Francisco J.; Buzsáki, Gyórgy; Freund, T.

In: Journal of Neuroscience, Vol. 20, No. 18, 15.09.2000, p. 6907-6919.

Research output: Contribution to journalArticle

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