The brain switch that controls freeze-or-flight survival instincts

Flee or freeze? In nature, survival hinges on making the right split-second choice when danger strikes, and the brain’s defensive circuits are built for exactly that task. Yet what counts as the “right” response depends on the landscape: in cluttered woods, swift flight into the underbrush can save your life; on exposed grassland, motionless hiding buys time. How does evolution solve this puzzle?

In a new study published in the scientific journal Nature, an international research team has uncovered an elegant mechanism that, by tweaking the sensitivity of a danger-response hub in the brain, tailors behavior to each environment without redesigning the whole system. The two co- first authors are Katja Reinhard, a former postdoc at NERF, Belgium, and now leading her own group at SISSA, Italy, and Felix Baier from Harvard University.