Figure 1: Visual representation of components of the brain’s threat-responsive circuitry.

Threats are classified on the basis of proximity, with the top of the figure showing a threat continuum, including distant predators, an approaching threatening person, or a direct encounter with painful stimuli. Components of the brain’s circuitry involved in threat responses appear in distinct colours, with the hippocampus in blue, stria terminalis and its bed nucleus in green, amygdala in red, and frontal regions, including the medial prefrontal cortex and insula, in purple. These circuitry components interact in unique ways depending on the nature of threats, thereby generating adaptive defensive responses shown at the bottom of the figure, including avoidance, freezing, fleeing, and fighting. BNST=bed nucleus of the stria terminalis.