1st Breaking Video IT_Pro 27/11/2018 Optogenetics

Consolato Sergi, M.D., Ph.D. University of Alberta Hospital Optogenetics Consolato Sergi, M.D., Ph.D. University of Alberta Hospital 27/11/2018 Optogenetics

2nd Video - Optogenetics Optogenetics_ Controlling the brain with light? 27/11/2018 Optogenetics

Signals Single-electrode recordings - Limitations - Intracellular recordings: Only a few neurons and difficult in vivo - Extracellular recordings: No capture information about sub- threshold activity, bias against small cells, poorly defined cell identities 2-deoxyglucose (2DG) imaging (H3 or C14) - Limitations - Visualization of active brain areas or neurons (post-mortem) - Temporal resolution in min or hrs, not msec. - ‘One-shot’ or ‘two-shot’ ways. PET/fMRI: poor spatio-temporal resolution, hemodynamic transformation, drug receptor activation patterns. Optical Intrinsic Signal Imaging (OISI): hemodynamic response in local capillaries related to local activity. Voltage Sensitive Dye Imaging (VSDI): membrane voltage, mostly sub-threshold activity in neurones and glia cells. 27/11/2018 Optogenetics

Optogenetics should allow fast depolarization / hyperpolarization of specific cells in living animals precise control and study of cell population dynamics the identification of causal positive and negative proof with cell specificity superior targeting & biocompatibility vs. electrical stimulation visual confirmation of target morphology using fluorescent labeling 27/11/2018 Optogenetics

Channelrhodopsin-2 (ChR2) Light-activated non-selective cation channel Chlamydomonas reinhardtii- Wikipedia Zhang F, Wang L-P, Boyden ES and Deisseroth K (2006) Channelrhodopsin-2 and optical control of excitable cells. Nature Methods 3(10): 785–792. Channelrhodopsin-2 (ChR2) Light-activated non-selective cation channel Alga: Chlamydomonas reinhardtii Requires all-trans retinal (ATR), which is present in mammals 50 fS per channel -> 0.1–1M ChR2 molecules are required to achieve 1 nA 27/11/2018 Optogenetics

Light-activated chloride pump Archaebacterium Natronomas pharaonis Zhang et al (2007) Multimodal fast optical interrogation of neural circuitry. Nature 446: 633–641. Archaea – Wikipedia Halorhodopsin (NpHR) Light-activated chloride pump Archaebacterium Natronomas pharaonis 22 mW/mm2 @ 560 +/- 27 nm Inactivates after ~1 sec 27/11/2018 Optogenetics

Current Status of Applications Some published work in animals (e.g. mouse & zebrafish): Control and mapping of the function of motor cortex Expression restores light responses in retinal ganglion cells Dissection of Parkinson’s circuitry Dissection of role of DA neurons in behavioral conditioning Temporally precise in vivo control of intracellular signaling Potential control of epileptiform activity High-speed mapping of synaptic connectivity Dissection of a behavioral module in the spinal cord 27/11/2018 Optogenetics

...but how much is there to be discovered? Take Home Message Optogenetics is Nature Method of the Year 2010 and is going to have more biology applications in the future!!! ...but how much is there to be discovered? …is it up to us? More Information on Pub Med and on website of Dr. Chou Hung, Ph.D. vision.ym.edu.tw/courses/methods/Presenta tion2.ppt Thank you 27/11/2018 Optogenetics