Reversible inactivation of the medial septum: selective effects on the spontaneous unit activity of different hippocampal cell types

S. J.Y. Mizumori, C. A. Barnes, B. L. McNaughton

Research output: Contribution to journalArticle

76 Scopus citations

Abstract

The contribution of septal afferents to spontaneous hippocampal single unit activity was examined by reversibly inactivating the medial septal nucleus using microinjections of the local anethetic lidocaine. Septal inactivation reduced spontaneous firing of cells in stratum granulosum and in the hilar/CA3 region for periods of up to about 15 min. The firing rates of CA1 complex-spike (pyramidal) cells, however, were not changed, although CA1 theta cells (inhibitory interneurons) exhibited a significant reduction in spontaneous rate. One interpretation of this pattern of results is that the output of CA1 pyramidal cells is maintained roughly constant in spite of reduced input from CA3 because of a proportional reduction in feedforward inhibition. This interpretation is consistent with Marr's22 formulation of the manner in which the hippocampus implements distributed associative memory. Alternatively, afferents to CA1 originating from regions other than CA3 may play a larger role in regulating CA1 output than previously assumed.

Original languageEnglish (US)
Pages (from-to)99-106
Number of pages8
JournalBrain Research
Volume500
Issue number1-2
DOIs
StatePublished - Oct 23 1989
Externally publishedYes

Keywords

  • Hippocampus
  • Lidocaine
  • Medial septum
  • Single unit activity

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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