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Neuron. 2016 Oct 5;92(1):240-251. doi: 10.1016/j.neuron.2016.09.003. Epub 2016 Sep 22.

Gamma-Rhythmic Gain Modulation.

Author information

1
Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Deutschordenstraße 46, 60528 Frankfurt, Germany; International Max Planck Research School for Neural Circuits, Max-von-Laue-Straße 4, 60438 Frankfurt, Germany.
2
Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Deutschordenstraße 46, 60528 Frankfurt, Germany.
3
Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
4
Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Deutschordenstraße 46, 60528 Frankfurt, Germany; Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen, Kapittelweg 29, 6525 EN Nijmegen, Netherlands. Electronic address: pascal.fries@esi-frankfurt.de.

Abstract

Cognition requires the dynamic modulation of effective connectivity, i.e., the modulation of the postsynaptic neuronal response to a given input. If postsynaptic neurons are rhythmically active, this might entail rhythmic gain modulation, such that inputs synchronized to phases of high gain benefit from enhanced effective connectivity. We show that visually induced gamma-band activity in awake macaque area V4 rhythmically modulates responses to unpredictable stimulus events. This modulation exceeded a simple additive superposition of a constant response onto ongoing gamma-rhythmic firing, demonstrating the modulation of multiplicative gain. Gamma phases leading to strongest neuronal responses also led to shortest behavioral reaction times, suggesting functional relevance of the effect. Furthermore, we find that constant optogenetic stimulation of anesthetized cat area 21a produces gamma-band activity entailing a similar gain modulation. As the gamma rhythm in area 21a did not spread backward to area 17, this suggests that postsynaptic gamma is sufficient for gain modulation.

KEYWORDS:

Channelrhodopsin; attention; communication-through-coherence (CTC); effective connectivity; gain; gamma; oscillation; rhythm; synchronization; visual cortex

PMID:
27667008
PMCID:
PMC5053905
DOI:
10.1016/j.neuron.2016.09.003
[Indexed for MEDLINE]
Free PMC Article

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