Title: Volumetric Voltage Imaging System using FACED and Plenoptic Illumination for Whole Central Nervous System Imaging of Zebrafish Larvae at ~ 1 kHz Volume rate

Capturing accurate neural data over different brain regions is essential to analyzing and understanding information processing in the vertebrate brain. Calcium imaging is a useful microscopy method for analyzing neural activity over large volumes with sub-cellular resolution. However, this method measures fluorescence based on calcium changes, which are correlated to but not directly reflective of neural activity. Voltage imaging is a promising alternative that measures fluorescence based on the electricity of neural signals, providing a direct indicator of neural activity. However, electrical signals are much faster than chemical (calcium) signals. Therefore, an imaging system that wants to employ voltage imaging must scan at least two orders of magnitude faster than that of calcium imaging. Few imaging techniques exist that achieve the ultrafast scanning speeds and large 3D field of view (FOV) required to make voltage imaging viable for analyzing large neuronal populations. We plan to develop a system that utilizes two imaging techniques, Free-space Angular Chirp Enhanced Delay (FACED) and plenoptic illumination (PI), to scan at kHz-order volume rates over mesoscopic-scale (mm-order) regions. Taking advantage of this combination of speed and FOV that has rarely been achieved, we then plan to use the system to image nearly the entire central nervous system (CNS) of zebrafish larvae and create whole-body neural mapping for optomotor response (OMR). This system will be the first of its kind to map whole-CNS OMR neural circuitry using voltage data, providing a more accurate framework for analyzing OMR that accounts for the true nature of neural activity.