The value assigned to aversive events is susceptible to contextual influences. Here, we asked whether a change in the valuation of negative events is reflected in an altered neuronal representation of their expected aversive outcome. We show that experiencing an aversive event in the past, and choosing to experience it in the future, reduces its aversive value. This psychological change is mirrored in an altered neural representation of aversive value in the caudate nucleus and anterior cingulate cortex. Our findings indicate that subcortical regions known to track expected value such as the caudate nucleus, together with anterior cingulate cortical regions implicated in emotional modulation, mediate a revaluation in expectancies of aversive states. The results provide a striking example of a contextual sensitivity in how the brain ascribes value to events, in a manner that may foster resilience in the face of adversity.