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Title

Rhythmic firing of medial septum non-cholinergic neurons

Authors
Williams, S.
Khateb, A.
Fort, Patrice
Published in Neuroscience. 1996, vol. 75, no. 3, p. 671-675
Abstract The presence of theta rhythm (5-10 Hz) in the hippocampus has been shown to enable long-term potentiation, a synaptic mechanism which has been proposed to underlie learning and memory. Medial septum cholinergic and GABAergic neurons that project to the hippocampus have been hypothesized to play conjointly a major role in the genesis of this rhythm. Building upon previous studies that have established the electrophysiological criteria for distinguishing cholinergic and non-cholinergic neurons in this area, it is demonstrated here that medial septum non-cholinergic neurons, putatively GABAergic, have the ability to discharge in rhythmic clusters of action potentials occurring at frequencies ranging from 1 to 8 Hz. Within the clusters, the firing frequency of action potentials varied between 13 and 57 Hz in a voltage-dependent manner. In addition, small voltage-dependent subthreshold membrane potential oscillations (16-54 Hz) were observed between clusters. Both subthreshold oscillations and clusters were eliminated by tetrodotoxin at 1 microM. These results indicate that non-cholinergic medial septum neurons could convey to the hippocampus not only theta but also higher frequency rhythmicity in the beta-gamma range (20-60 Hz).
Keywords AnimalsCarbachol/ pharmacologyCholinergic Fibers/ physiologyGuinea PigsMembrane Potentials/drug effects/ physiologyRatsSeptal Nuclei/ physiology
Stable URL http://archive-ouverte.unige.ch/unige:10448
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PMID: 8951863
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