Fast multi-photon brain-wide volumetric imaging and photostimulation

The ability to simultaneously detect and control neuronal activity grants the capacity to unravel the causal relationships behind brain processing. Nevertheless, scaling-up this technology to the whole encephalon of a vertebrate is a challenging task, and this impedes reaching a global comprehension of how the brain works. To this aim, we developed an optical system that enables fast noninvasive functional imaging of the whole brain of the zebrafish larva and, at the same time, allows us to optogenetically stimulate the activity of arbitrary sets of neurons in the volume. Our preliminary results show that with this optical system we can both consistently evoke activation of neurons in the stimulation site and identify distantly-located functionally-connected neurons placed downstream in the activated circuits. The expansibility of this concept paves the way for the brain-wide mapping of functional connectivity in the zebrafish larva.