The executive lands on top: working memory, inhibitory control that finally pulls the brakes, a goal register, conflict monitoring — and a stress dial that drops the PFC offline and lets the amygdala run unopposed.
WHAT THE PFC ACTUALLY IS. Not "the rational part" — the executive. It governs the rest: holds ~4 items in working memory, exerts top-down inhibition, maintains goals across time, arbitrates conflicts. Last structure to mature (~25y), first to fail under stress or fatigue. v2 gave you an amygdala that could tag threat but not act on it — the brakes existed with no foot on the pedal. The PFC is the foot. And when it goes offline, you watch the pedal lift.
Live executive — drive the stress and maturation dials
2D · the executive (top) sends inhibitory-control fibers down to the brakes; control strength = bar height. Push stress up and watch the fibers thin, then snap — amygdala flags fire unopposed below the hijack line.
3D · full topology: 30 cortical + hippocampus (purple) + amygdala (red) + prefrontal executive (blue, top). Blue fibers = top-down control; they fade as stress rises. Drag to rotate.
Diagnostics — executive control math re-verified at load
TODDLER CORNER
The brain got its boss. The boss sits on top, holds a few things in mind at once, keeps the goal, and decides which brakes to press. But the boss is expensive and gets tired — and when it's too tired or too young, it clocks out, and the fast scared part takes the wheel with nobody checking it. That's what "losing your cool" is: the boss went offline. Slide the tired-dial up and watch it happen.
LIT neuroscience + live control arithmetic · AMBER control scale (PFC_MAX), salience normalization, and the corpus mapping are editorial. Red card = miswired.