Fear in action: Fear conditioning and alleviation through body movements

Abstract

Learning a predictive cue of a threat - threat conditioning - allows us to prevent direct contact with the threat. In animals, threat-conditioned cues induce fear-like body movements such as freezing. Interestingly, training animals with alternative bodily defenses to avoid harm could reduce conditioned fear-like responses, suggesting that the physical capacity to actively defend against a threat could help overcome passively induced fear. However, evidence for the role of body movements in acquisition and alleviation of human fear is scarce. In the present study, human participants showed a deviation of multidimensional body movement patterns as threat conditioning progressed in a naturalistic virtual setting. The subsequent training to exert defensive body movements to prevent harm weakened the conditioned body movements and resulted in a long-term (24 hrs) reduction of the physiological responses and subjective fear toward the conditioned cues. Unlike the passive extinction procedure, the training of defensive body movements was resistant to spontaneous recovery of a fear response. The alleviating effect of the active defense training was observed when participants physically defended themselves but not when they merely observed another person vicariously defending against a threat on their behalf. These results suggest the critical role of body movements in both acquisition and reduction of conditioned fear among humans. Further investigations may leverage more embodied procedures to advance mechanistic understandings and clinical interventions of human fear memories.