Safety-relevant experience reshapes neural codes for ambiguous threat in adolescents

Visually threatening stimuli often carry ambiguous meanings, but experience can alter their representation toward safety. No existing studies have examined how neural representations are reshaped during this process. Adolescence is marked by the ongoing maturation of neural circuits supporting flexible contextual processing, which may shape how safety experience alters threat representations. This study created a safety-relevant context in which visually threatening stimuli (animals, weapons) acquired meanings in relation to personal safety, with animals signaling danger and weapons conferring protection. Using 7T fMRI, we measured neural responses in 33 adolescents (MAge = 14.88 years, 19 females) during passive viewing before (Pre-task) and after (Post-task) the safety experience. At Post-task, protection stimuli elicited greater activation in the hippocampus, precuneus, and insula, reflecting experience-dependent updating. Threat stimuli showed more restricted changes in the precuneus, suggesting persistence of initial threat representations. Both stimuli showed greater Pre-task activation in higher-level visual processing regions, reflecting stimulus novelty. MVPA indicated greater representational updating for protection than threat and convergent neural patterns for stimuli matched in safety value at Post-task. These findings may inform anxiety interventions explicitly training adolescents to recognize and use protective resources in aversive contexts to enhance safety updating, complementing traditional threat-extinction approaches.