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

Visually threatening stimuli often carry ambiguous meanings. For example, a gun can be used against an individual as a threat or on their behalf as protection. Experience with such ambiguous stimuli can reshape their neural representations. Yet little is known about how this reorganization unfolds during adolescence, when neural circuits supporting flexible contextual processing are still maturing. This study created a safety-relevant context in which visually threatening stimuli (animals, weapons) acquired meanings related to personal safety, with animals signaling danger and weapons conferring protection. Using 7 T 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 regions associated with contextual updating and memory retrieval, whereas threat stimuli showed more restricted changes. Both stimulus types showed greater pre-task activation in regions supporting visual processing and stimulus-driven attention, consistent with heightened vigilance toward novel stimuli. Multivoxel pattern classification analysis indicated representational updating for both protection and threat, and convergent neural patterns for stimuli matched in safety value at post-task. These findings provide a framework for understanding how threatening stimuli can be neurally updated as signals of safety following relevant experience.