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"Fiber-optic neurointerfaces for opto- and thermogenetics"

Dr. Aleksei Zheltikov
Texas A&M University


Optogenetic technologies offer unique tools for spatially precise, cell-specific neuromodulation, allowing specific types of neuron within dense neuron circuits in brain to be selectively addressed and precisely manipulated. Specifically designed and carefully optimized fiber-optic interfaces help extend optogenetic methods to deeper brain regions. Implantable fiber-optic interfaces enabling parallel long-term optogenetic interrogation of distinctly separate, functionally different sites in the brain of freely moving mice have been demonstrated. Cognitive tests on representative groups of freely behaving transgenic mice are shown to enable a quantitative characterization of reconnectable implantable fiber-optic neurointerfaces for optogenetic neurostimulation. A systematic analysis of such tests provides a robust quantitative measure for the cognitive effects induced by fiber-optic neurostimulation, validating the performance of fiber-optic neurointerfaces for long-term optogenetic brain stimulations and showing no statistically significant artifacts in the behavior of transgenic mice due to interface implantation. Suitably tailored fiber probes are shown to enable a localized, precisely controlled heating of individual cells expressing heat-sensitive genetically encoded thermosensitive channels. Optically detected electron spin resonance in fiber-coupled nitrogenĖvacancy (NV) centers of diamond is used to demonstrate a fiber-optic quantum thermometry of individual thermogenetically activated neurons. Laser-induced temperature variations read out from single neurons with the NV-diamond fiber sensor are shown to strongly correlate with the fluorescence of calcium-ion sensors, serving as online indicators of the inward Ca2+ current across the cell membrane of neurons expressing transient receptor potential (TRP) cation channels. Local laser heating above the TRP-channel activation threshold is shown to reproducibly evoke robust action potentials, visualized by calcium-ion-sensor-aided fluorescence imaging and detected as prominent characteristic waveforms in the time-resolved response of fluorescence Ca2+ sensors.

Wednesday, September 14, 2016
IQSE 578, 12:30 Noon
Mitchell Physics Building

Institute for Quantum Science and Engineering
Texas A&M University

(Sandwiches, chips, and water to be served at 12:00 noon)