Origin of Gamma Frequency Power during Hippocampal Sharp-Wave Ripples.
Author: Oliva A1, Fernández-Ruiz A2, Fermino de Oliveira E3, Buzsáki G4
Affiliation:
1New York University Neuroscience Institute, New York, NY 10016, USA; Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.
2New York University Neuroscience Institute, New York, NY 10016, USA.
3New York University Neuroscience Institute, New York, NY 10016, USA; Center for Mathematics, Computing and Cognition, Universidade Federal do ABC, São Bernardo do Campo, São Paulo, Brazil.
4New York University Neuroscience Institute, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10016, USA. Electronic address: gyorgy.buzsaki@nyumc.org.
Conference/Journal: Cell Rep.
Date published: 2018 Nov 13
Other:
Volume ID: 25 , Issue ID: 7 , Pages: 1693-1700 , Special Notes: doi: 10.1016/j.celrep.2018.10.066. , Word Count: 166
Hippocampal sharp-wave ripples (SPW-Rs) support consolidation of recently acquired episodic memories and planning future actions by generating ordered neuronal sequences of previous or future experiences. SPW-Rs are characterized by several spectral components: a slow (5-15 Hz) sharp-wave, a high-frequency "ripple" oscillation (150-200 Hz), and a slow "gamma" oscillation (20-40 Hz). Using laminar hippocampal recordings and optogenetic manipulations, we dissected the origin of these spectral components. We show that increased power in the 20-40 Hz band does not reflect an entrainment of CA1 and CA3 neurons at gamma frequency but the power envelope of overlapping ripples. Spike-local field potential coupling between unit firing in CA1 and CA3 regions during SPW-Rs is lowest in the gamma band. Longer SPW-Rs are preceded by increased firing in the entorhinal cortex. Thus, fusion of SPW-Rs leads to lengthening of their duration associated with increased power in the slow gamma band without the presence of true oscillation.
KEYWORDS: entorhinal cortex; gamma; hippocampus; memory consolidation; optogenetics; oscillations; sharp-wave ripples
PMID: 30428340 DOI: 10.1016/j.celrep.2018.10.066
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