Lin, J.Y. et al. Neuron 79, 241–253 (2013).

Neurons primarily communicate with each other via electrical bursts (action potentials) that are transmitted between cells through the release of chemical signals at synapses. With microbial opsins, researchers can trigger action potentials in neurons in response to light or block action potentials from occurring. But controlling the release of chemicals at specific synapses using light has not yet been possible. Lin et al. developed tools for this based on chromophore-assisted light inactivation (CALI), a technique in which illumination of a chromophore triggers the production of singlet oxygen molecules, which inactivate nearby proteins. They fused the CALI agent, miniSOG, to proteins that are important for triggering the release of chemicals by vesicles at presynaptic terminals. As a result, synaptic release of neurotransmitters in cells could be blocked over several hours, allowing dissection of the role of specific axonal projections in worm behavior.