Optogenetics in a transparent animal: circuit function in the larval zebrafish

Optogenetic tools can be used to manipulate neuronal activity in a reversible and specific manner. In recent years, such methods have been applied to uncover causal relationships between activity in specified neuronal circuits and behavior in the larval zebrafish. In this small, transparent, genetic model organism, noninvasive manipulation and monitoring of neuronal activity with light is possible throughout the nervous system. Here we review recent work in which these new tools have been applied to zebrafish, and discuss some of the existing challenges of these approaches.

► The transparency of the larval zebrafish allows for non-invasive optogenetic detection and modulation of neural activity throughout the brain. ► Monitoring of neural activity identifies neuronal populations that might be involved in diverse behavior. ► A fictive virtual reality system for larval zebrafish allows for neuronal recording and optical perturbation during behavioral assays. ► Perturbation of the activity of selected groups of neurons in freely swimming animals remains a challenge.