Document Detail

Running speed alters the frequency of hippocampal gamma oscillations.
MedLine Citation:
PMID:  22623683     Owner:  NLM     Status:  MEDLINE    
Successful spatial navigation is thought to employ a combination of at least two strategies: the following of landmark cues and path integration. Path integration requires that the brain use the speed and direction of movement in a meaningful way to continuously compute the position of the animal. Indeed, the running speed of rats modulates both the firing rate of neurons and the spectral properties of low frequency, theta oscillations seen in the local field potential (LFP) of the hippocampus, a region important for spatial memory formation. Higher frequency, gamma-band LFP oscillations are usually associated with decision-making, increased attention, and improved reaction times. Here, we show that increased running speed is accompanied by large, systematic increases in the frequency of hippocampal CA1 network oscillations spanning the entire gamma range (30-120 Hz) and beyond. These speed-dependent changes in frequency are seen on both linear tracks and two-dimensional platforms, and are thus independent of the behavioral task. Synchrony between anatomically distant CA1 regions also shifts to higher gamma frequencies as running speed increases. The changes in frequency are strongly correlated with changes in the firing rates of individual interneurons, consistent with models of gamma generation. Our results suggest that as a rat runs faster, there are faster gamma frequency transitions between sequential place cell-assemblies. This may help to preserve the spatial specificity of place cells and spatial memories at vastly different running speeds.
Omar J Ahmed; Mayank R Mehta
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  32     ISSN:  1529-2401     ISO Abbreviation:  J. Neurosci.     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-05-24     Completed Date:  2012-08-03     Revised Date:  2013-06-24    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7373-83     Citation Subset:  IM    
Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA.
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MeSH Terms
Action Potentials / physiology
Brain Waves / physiology*
CA1 Region, Hippocampal / physiology*
Interneurons / physiology
Pyramidal Cells / physiology
Rats, Long-Evans
Running / physiology*
Spatial Behavior / physiology
Theta Rhythm / physiology
Grant Support
1-R01-MH-092925-01/MH/NIMH NIH HHS; F31 MH081477/MH/NIMH NIH HHS; MH081477/MH/NIMH NIH HHS

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