Driving fast-spiking cells induces gamma rhythm and controls sensory responses.

Cardin J., Carlén M., Meletis K., Knoblich U., Zhang F., Deisseroth K., Tsai L., Moore C., ,

Nature , 459(7247):663-667 [doi: 10.1038/nature08002] , April 26, 2009

Abstract: Corticalgamma oscillations (20280 Hz) predict increases in focused attention, and failure ingamma regulation is a hallmark of neurological and psychiatric disease. Current theory predicts that gamma oscillations are generated by synchronous activity of fast-spiking inhibitory interneurons, with the resulting rhythmic inhibition producing neural ensemble synchrony by generating a narrow window for effective excitation. We causally tested these hypotheses in barrel cortex in vivo by targeting optogenetic manipulation selectively to fast-spiking interneurons. Here we show that light-driven activation of fast-spiking interneurons at varied frequencies (82200 Hz) selectively amplifies gamma oscillations. In contrast, pyramidal neuron activation amplifies only lower frequency oscillations, a cell-type-specific double dissociation. We found that the timing of a sensory input relative to a gamma cycle determined the amplitude and precision of evoked responses. Our data directly support the fast-spiking-gamma hypothesis and provide the first causal evidence that distinct network activity states can be induced in vivo by cell-type-specific activation.

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