Ultra-Widefield All-Optical Neurophysiology in Tissue

Date: 

Wednesday, October 4, 2017, 1:00pm

Location: 

NW 243

CBS Neurolunch
(Lunch available at 12:45 pm)

Samouil Farhi, PhD Student, Cohen Lab

All-optical approaches for simultaneous recording and perturbation of neuronal activity could enable functional mapping of brain circuits. Spectral overlap of actuators and reporters presents a challenge for their simultaneous use, while optical scattering and out-of-focus fluorescence are challenges for imaging densely labeled samples over large fields of view. To overcome the first challenge, we coupled a red-shifted calcium indicator with a spectrally-orthogonal blue-shifted channelrhodopsin, enabling single-photon all-optical neurophysiology. To overcome the second challenge, we designed an ultra-widefield optical system to image a 5 mm field of view with single-cell lateral resolution. A digital micromirror device illuminates neighboring sample locations with temporally orthogonal light sequences based on Hadamard matrices, enabling computational rejection of scattering and out-of-focus light. By uniting these molecular and optical tools we measure functional properties of thousands of neurons in parallel in acute slices. We map the effects of anti-epileptic drugs on excitability throughout the cortex and striatum.  We also map the post-synaptic responses driven by layer 5 cortical neurons in cortex and striatum.  These results demonstrate a robust tool for wide-area mapping of neuronal excitability and synaptic transmission in acute brain slices.