title: Driving fast-spiking cells induces gamma rhythm and controls sensory responses.
abstract: Cortical gamma oscillations (20-80 Hz) predict increases in focused attention, and failure in gamma 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 (8-200 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.
authors.affiliation: McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, MIT, Cambridge, Massachusetts 02139, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Cardin
authors.forename: Marie
authors.initials: M
authors.lastname: Carlén
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Meletis
authors.forename: Ulf
authors.initials: U
authors.lastname: Knoblich
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Karl
authors.initials: K
authors.lastname: Deisseroth
authors.forename: Li-Huei
authors.initials: LH
authors.lastname: Tsai
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Moore
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii; D004594:Electrophysiology; D005786:Gene Expression Regulation; D055879:Gene Knock-In Techniques; D007395:Interneurons / Q000502:physiology*; D051379:Mice; D010775:Photic Stimulation; D017966:Pyramidal Cells / Q000502:physiology; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology* / Q000378:metabolism*
chemical_list: D012243:Rhodopsin