Self-timed movement initiation requires rapid sequential coordination of circuits in prefrontal cortex and cerebellum.

The neural 'chain of events' necessary for movement initiation is poorly understood, particularly for endogenous actions that are self-timed. Here, we introduce a new task that requires mice to self-initiate a movement with high temporal precision in the absence of external 'go' signals. Brief, precisely timed flashes of optogenetic photoinhibition reveal that movement initiation is causally driven by rapid sequential recruitment of neurons in prefrontal cortex and lateral cerebellum.