KHz-rate volumetric voltage imaging of the whole zebrafish heart

Fast volumetric imaging is essential for understanding the function of excitable tissues such as those found in the brain and heart. Measuring cardiac voltage transients in tissue volumes with spatial and temporal resolutions needed to give insight to cardiac function has so far been impossible. We introduce a new imaging modality based on simultaneous illumination of multiple planes in the tissue and parallel detection with multiple cameras, avoiding compromises inherent in any scanning approach. The system enables imaging of voltage transients in-situ, allowing us, for the first time, to map voltage activity in the whole heart volume at KHz rates. The unprecedented spatio-temporal resolution of our method enabled the observation of novel dynamics of electrical propagation through the zebrafish atrioventricular canal.