In haunted houses across the country this month, threatening figures will jump out of the shadows, prompting visitors—wide-eyed and heart racing—to instinctively freeze and flee.

Evolutionarily speaking, this “innate threat response” is key to survival, helping a wide variety of animal species escape predators. But when stuck in overdrive it can cause problems for humans.

A University of Colorado Boulder research team has identified a novel brain circuit responsible for orchestrating this threat response. Known as the interpeduncular nucleus (IPN), this dense cluster of specialized neurons not only jump-starts that freeze-and-flee reaction, but dials it down when animals learn there’s no real danger.