| Different origins of gamma rhythm and high-gamma activity in macaque visual cortex. | |
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MedLine Citation:
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PMID: 21532743 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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During cognitive tasks electrical activity in the brain shows changes in power in specific frequency ranges, such as the alpha (8-12 Hz) or gamma (30-80 Hz) bands, as well as in a broad range above ∼80 Hz, called the high-gamma band. The role or significance of this broadband high-gamma activity is unclear. One hypothesis states that high-gamma oscillations serve just like gamma oscillations, operating at a higher frequency and consequently at a faster timescale. Another hypothesis states that high-gamma power is related to spiking activity. Because gamma power and spiking activity tend to co-vary during most stimulus manipulations (such as contrast modulations) or cognitive tasks (such as attentional modulation), it is difficult to dissociate these two hypotheses. We studied the relationship between high-gamma power, gamma rhythm, and spiking activity in the primary visual cortex (V1) of awake monkeys while varying the stimulus size, which increased the gamma power but decreased the firing rate, permitting a dissociation. We found that gamma power became anti-correlated with the high-gamma power, suggesting that the two phenomena are distinct and have different origins. On the other hand, high-gamma power remained tightly correlated with spiking activity under a wide range of stimulus manipulations. We studied this relationship using a signal processing technique called Matching Pursuit and found that action potentials are associated with sharp transients in the LFP with broadband power, which is visible at frequencies as low as ∼50 Hz. These results distinguish broadband high-gamma activity from gamma rhythms as an easily obtained and reliable electrophysiological index of neuronal firing near the microelectrode. Further, they highlight the importance of making a careful dissociation between gamma rhythms and spike-related transients that could be incorrectly decomposed as rhythms using traditional signal processing methods. |
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Authors:
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Supratim Ray; John H R Maunsell |
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Publication Detail:
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Type: Journal Article Date: 2011-04-12 |
Journal Detail:
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Title: PLoS biology Volume: 9 ISSN: 1545-7885 ISO Abbreviation: PLoS Biol. Publication Date: 2011 Apr |
Date Detail:
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Created Date: 2011-05-02 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101183755 Medline TA: PLoS Biol Country: United States |
Other Details:
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Languages: eng Pagination: e1000610 Citation Subset: IM |
Affiliation:
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Department of Neurobiology & Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, United States of America. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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