Abstract
Several recently developed Channelrhodopsin (ChR) variants are characterized by rapid kinetics and reduced desensitization in comparison to the widely used ChR2. However, little is known about how varying opsin properties may regulate their interaction with local network dynamics. We compared evoked cortical activity in mice expressing three ChR variants with distinct temporal profiles under the CamKII promoter: Chronos, Chrimson, and ChR2. We assessed overall neural activation by measuring the amplitude and temporal progression of evoked spiking. Using γ-range (30–80 Hz) local field potential (LFP) power as an assay for local network engagement, we examined the recruitment of cortical network activity by each tool. All variants caused light-evoked increases in firing in vivo, but each demonstrated different temporal patterning of evoked activity. In addition, the three ChRs had distinct effects on cortical γ-band activity. Our findings suggest the properties of optogenetic tools can substantially affect their efficacy in vivo, as well their engagement of circuit resonance.
Footnotes
The authors declare no competing financial interests.
This work was supported by National Institutes of Health Grants R01 MH102365, R01 EY022951, R01 MH113852, and P30 EY026878; a Smith Family Award for Excellence in Biomedical Research; a Klingenstein Fellow-ship Award; an Alfred P. Sloan Fellowship; a National Alliance for Research on Schizophrenia and Depression Young Investigator Award; a grant from the Ludwig Foundation; and a McKnight Fellowship (J.A.C.).
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