Real-life shooting decisions typically occur under acute threat and require fast switching
between vigilant situational assessment and immediate fight-or-flight actions. Recent studies
suggested that freezing facilitates action preparation and decision-making but the
neurocognitive mechanisms remain unclear. We applied functional magnetic resonance
imaging, posturographic and autonomic measurements while participants performed a shooting
task under threat of shock. Two independent studies, in unselected civilians (N=22) and police
recruits (N=54), revealed that preparation for shooting decisions under threat is associated with
bodily freezing, bradycardia, midbrain activity (including the periaqueductal gray-PAG) and
PAG-amygdala connectivity. Crucially, stronger activity in the midbrain/PAG during this
preparatory stage of freezing predicted faster subsequent accurate shooting. Finally, the switch
from preparation to active shooting was associated with tachycardia, perigenual anterior
cingulate cortex (pgACC) activity and pgACC-amygdala connectivity. These findings suggest
that threat-anticipatory midbrain activity centred around the PAG supports decision-making by
facilitating action preparation and highlight the role of the pgACC when switching from
preparation to action. These results translate animal models of the neural switch from freeze-toaction.
In addition, they reveal a core neural circuit for shooting performance under threat and
provide empirical evidence for the role of defensive reactions such as freezing in subsequent
action decision-making.