Threat shooting tasks primarily engage the PAG-amygdala-pgACC circuit, where the periaqueductal gray (PAG) drives preparatory freezing and action readiness, the amygdala amplifies threat salience, and the perigenual anterior cingulate cortex (pgACC) triggers the switch to rapid shooting.[sec +1] PAG-Centered Preparation Midbrain PAG activates during threat anticipation, linking to reduced body sway (freezing) and faster reaction times for armed targets, co-activating with striatum and supplementary motor area for motor priming irrespective of threat level.[nature] pgACC Action Switch pgACC shows peak activity specifically during high-threat “shoot” decisions, enhancing connectivity with amygdala to override freezing and execute responses, distinguishing it from withhold trials.[elifesciences +1] Integrated Connectivity Functional connectivity along PAG-amygdala-pgACC strengthens under shock threat, with tachycardia marking the shift; this core circuit persists in police recruits, explaining biased shooting under stress.[sec +1]

The anterior cingulate cortex (ACC) and periaqueductal gray (PAG) form key nodes in threat-processing circuits, enabling rapid defensive actions during imminent danger. These regions activate in sequence as threats escalate, shifting from cognitive evaluation to instinctive survival responses.[nature +1] ACC Functions The ACC, particularly its rostral and dorsal portions, detects conflicts and assesses threat salience, integrating emotional and cognitive signals from the amygdala and prefrontal areas. It signals urgency via heightened activity during high-imminence threats, facilitating quick shifts in attention and behavior, such as from freeze to fight-or-flight.[elifesciences +1] PAG Role The PAG, especially its dorsolateral column (dlPAG), orchestrates reflexive defenses like fleeing or freezing when threats are proximal and escape is urgent. It receives ACC inputs to amplify cardio-respiratory changes and motor outputs, bypassing slower cortical deliberation for survival speed.[pubmed.ncbi.nlm.nih +1] Circuit Integration ACC projections to dlPAG provide top-down modulation, gating panic-like responses while PAG feedback loops sustain arousal. In humans, this supports adaptive reactions like avoidance in chronic pain or predator scenarios, with disruptions linked to anxiety disorders.[pmc.ncbi.nlm.nih +1]