Electric shock causes fear-like persistent behavioral response in the nematode Caenorhabditis elegans

Electricity is widely utilized as environmental stimulus to sense the world by many animal species. Despite its importance, however, molecular and physiological mechanisms for responding to electrical stimulus have been far less understood compared to other sensory stimuli. Here we report novel behavioral responses to electrical stimulus of the nematode C. elegans. When the animals on food are stimulated by alternating current, their movement speed suddenly increases more than 2-fold, which persists for a few minutes even after the electrical stimulation is terminated. Genetic analyses reveal that voltage-gated channels are required for the response, possibly as the sensors, and neuropeptide signaling suppresses the persistent response. Additional behavioral analysis reveals that, in addition to the persistence, the animals response to electrical shock is scalable and has a negative valence, which are recently regarded as emotion primitives, suggesting that the response may reflect a primitive form of "fear" of animals.