All-optical neurophysiology using high-speed wide-area optical sectioning
Vicente Parot, Harvard University

All-optical stimulation and recording of neural activity could characterize brain function over large areas, but requires compatible optogenetic actuators and reporters, and optical systems for stimulation and optically sectioned imaging in turbid tissue. To stimulate and record activity from thousands of neurons with one photon (1P), we paired a blue shifted channelrhodopsin (eTsChR) with a red-shifted calcium indicator (H2B-jRGECO1a). To image cellular-resolution activity in large areas (4.6 mm FOV) of acute brain slices, we used a digital micromirror device (DMD) to illuminate neighboring sample locations with orthogonal functions of time based on Hadamard codes, and rejected uncorrelated background. To record high-speed neuronal activity (500 Hz), we designed a compressed sensing strategy for Hadamard microscopy, obtaining one optical section every two camera frames. We made functional maps showing that these optogenetic and optical tools provide a powerful capability for wide-area interrogation of neuronal excitability and functional connectivity in acute brain slices.

Vicente Parot is the recipient of the 2019 OSA Deutsch Fellowship and will join the Wellman Center at MGH in October. Currently he is a Postdoctoral Fellow at the Harvard Chemistry Department, after obtaining his PhD in Biophysics at Harvard and in Medical Engineering and Medical Physics at MIT. During his graduate work with Adam E. Cohen, he invented a method for wide-area optical sectioning of high-speed neuronal activity movies to map neuronal function across brain tissue. Previously, he developed technologies for medical imaging as an MIT-Madrid M+Visión Fellow, aimed to reduce colorectal cancer mortality by increasing the sensitivity of colonoscopy to premalignant lesions, and to improve molecular imaging for oncology by multiplexing PET. He completed his Electrical Engineering and MS degrees at Catholic University of Chile where he developed a theoretical framework to enable cheaper MRI scanners.