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Proc Natl Acad Sci U S A. 2014 Sep 16;111(37):13535-40. doi: 10.1073/pnas.1411233111. Epub 2014 Sep 2.

Optogenetic activation of septal cholinergic neurons suppresses sharp wave ripples and enhances theta oscillations in the hippocampus.

Author information

1
Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102; Center for Interdisciplinary Research in Biology, Institut National de la Santé et de la Recherche Médicale U1050, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241, Collège de France, F-75005 Paris, France;
2
Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102; Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083, Budapest, Hungary;
3
Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102; Neuroscience Institute, School of Medicine, New York University, New York, NY 10016; and MTA-SZTE "Momentum" Oscillatory Neuronal Networks Research Group, Department of Physiology, University of Szeged, H-6720, Szeged, Hungary.
4
Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083, Budapest, Hungary;
5
Center for Interdisciplinary Research in Biology, Institut National de la Santé et de la Recherche Médicale U1050, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241, Collège de France, F-75005 Paris, France;
6
Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102; Neuroscience Institute, School of Medicine, New York University, New York, NY 10016; and Gyorgy.Buzsaki@nyumc.org.

Abstract

Theta oscillations in the limbic system depend on the integrity of the medial septum. The different populations of medial septal neurons (cholinergic and GABAergic) are assumed to affect different aspects of theta oscillations. Using optogenetic stimulation of cholinergic neurons in ChAT-Cre mice, we investigated their effects on hippocampal local field potentials in both anesthetized and behaving mice. Cholinergic stimulation completely blocked sharp wave ripples and strongly suppressed the power of both slow oscillations (0.5-2 Hz in anesthetized, 0.5-4 Hz in behaving animals) and supratheta (6-10 Hz in anesthetized, 10-25 Hz in behaving animals) bands. The same stimulation robustly increased both the power and coherence of theta oscillations (2-6 Hz) in urethane-anesthetized mice. In behaving mice, cholinergic stimulation was less effective in the theta (4-10 Hz) band yet it also increased the ratio of theta/slow oscillation and theta coherence. The effects on gamma oscillations largely mirrored those of theta. These findings show that medial septal cholinergic activation can both enhance theta rhythm and suppress peri-theta frequency bands, allowing theta oscillations to dominate.

KEYWORDS:

acetylcholine; channelrhodopsin-2; in vivo electrophysiology; silicon probe

PMID:
25197052
PMCID:
PMC4169920
DOI:
10.1073/pnas.1411233111
[Indexed for MEDLINE]
Free PMC Article

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