2018/2/23
Behaviour that braces us for looming danger is triggered by the brain cells responsible for arousal and reward.
Animals anticipate impending threats by recalling similar unpleasant experiences, and react accordingly. A team including researchers from the University of Tsukuba conditioned mice to fear a loud noise by following it with an electric shock to the foot. After a while, the loud noise made the mice freeze in fear. Studying the mice’s brain activity during the scary sound, the team found that orexin neurons, brain cells that respond to emotional cues, were activated. This triggered a reaction in noradrenergic neurons — brain cells that mobilize the body for action. Blocking this circuit made the mice freeze less, but stimulating it made them freeze more, even when a slightly different sound was played.
This brain circuit could help explain why traumatic experiences can make people fearful of similar yet safe situations.
- Nature Communications 8, 1606 (2017). doi: 10.1038/s41467-017-01782-z