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Strength of Gamma Rhythm Depends on Normalization

Ray, Supratim and Ni, Amy M and Maunsell, John HR (2013) Strength of Gamma Rhythm Depends on Normalization. In: PLOS BIOLOGY, 11 (2).

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Official URL: http://dx.doi.org/10.1371/journal.pbio.1001477


Neuronal assemblies often exhibit stimulus-induced rhythmic activity in the gamma range (30-80 Hz), whose magnitude depends on the attentional load. This has led to the suggestion that gamma rhythms form dynamic communication channels across cortical areas processing the features of behaviorally relevant stimuli. Recently, attention has been linked to a normalization mechanism, in which the response of a neuron is suppressed (normalized) by the overall activity of a large pool of neighboring neurons. In this model, attention increases the excitatory drive received by the neuron, which in turn also increases the strength of normalization, thereby changing the balance of excitation and inhibition. Recent studies have shown that gamma power also depends on such excitatory-inhibitory interactions. Could modulation in gamma power during an attention task be a reflection of the changes in the underlying excitation-inhibition interactions? By manipulating the normalization strength independent of attentional load in macaque monkeys, we show that gamma power increases with increasing normalization, even when the attentional load is fixed. Further, manipulations of attention that increase normalization increase gamma power, even when they decrease the firing rate. Thus, gamma rhythms could be a reflection of changes in the relative strengths of excitation and normalization rather than playing a functional role in communication or control.

Item Type: Journal Article
Publication: PLOS BIOLOGY
Additional Information: Copyright for this article belongs to PUBLIC LIBRARY SCIENCE, USA
Department/Centre: Division of Biological Sciences > Centre for Neuroscience
Date Deposited: 25 Mar 2013 10:23
Last Modified: 25 Mar 2013 10:23
URI: http://eprints.iisc.ac.in/id/eprint/46171

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