Optogenetic Approaches for Mesoscopic Brain Mapping
Recent advances in identifying genetically unique neuronal proteins has revolutionized the study of brain circuitry. Researchers are now able to insert specific light-sensitive proteins (opsins) into a wide range of specific cell types via viral injections or by breeding transgenic mice. These opsins enable the activation, inhibition, or modulation of neuronal activity with millisecond control within distinct brain regions defined by genetic markers. Here we present a useful guide to implement this technique into any lab. We first review the materials needed and practical considerations and provide in-depth instructions for acute surgeries in mice. We conclude with all-optical mapping techniques for simultaneous recording and manipulation of population activity of many neurons in vivo by combining arbitrary point optogenetic stimulation and regional voltage-sensitive dye imaging. It is our intent to make these methods available to anyone wishing to use them.
Key wordsOptogenetics Virus Transgenic Mouse Neuron Circuit Brain Channelrhodopsin (ChR2) Voltage-sensitive dyes (VSD)
This work was supported from the Natural Sciences and Engineering Research Council of Canada Discovery Grant, the Alberta Alzheimer Research Program, and the Alberta Innovates: Health Solutions to M.H.M. and NSERC CREATE BIP Postdoctoral Trainee Grant to M.K. M.H.M. is the holder of the CAIP chair in Brain Function in Health and Dementia.
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