Ahrens, M.B., et al. Nature 485, 471–477 (2012).

Our movements often adapt to what we see in complex ways. Fish, for example, adjust their swimming speed according to the visual perception of how fast their surroundings move. To study how this is achieved at the cellular level, Ahrens et al. captured the activity of individual neurons throughout the brain of paralyzed zebrafish larvae using two-photon imaging of a genetically encoded calcium sensor. The group then linked brain activity and behavior by developing a 'swim simulator' in which they controlled the rate at which the virtual world seemed to move while simultaneously measuring the fish's motor intentions via electrophysiological recordings from the relevant motor nerves. This fictively driven virtual-reality setup allowed them to study neural dynamics during visually guided motor adaptation.