A shared threat-anticipation circuit is dynamically engaged at different moments by certain and uncertain threat.

is a sustained response to uncertain-or-distal harm. Prior work begun to reveal the neural systems recruited by different threats, but has yet to plumb the moment-by-moment dynamics anticipated by theory and behavioral research. Here we used a novel combination of neuroimaging techniques to demonstrate that certain and uncertain threat recruit a shared threat-anticipation circuit. Activity in this circuit and covert measures of distress showed similar patterns of context-dependent dynamics, exhibiting persistent increases when anticipating uncertain-threat encounters and transient surges in the seconds before certain encounters. These observations provide fresh insights into the neurobiology of fear and anxiety, laying the groundwork for more ambitious clinical and mechanistic research.