Figure 3. Neurobehavioral model of active avoidance.

(A) Pavlovian SSDRs like freezing dominate early in avoidance training and are controlled by LA and CeA. (B) With exposure to instrumental contingencies, IL is recruited to suppress competing CeA-dependent SSDRs and threat processing is diverted to BA and striatal regions important for the learning and performance of goal-directed ARs. At this stage, VTA responses in striatum also contribute to response-selection (SSDR vs. AR, via suppression or facilitation of WS-evoked dopamine) and encode safety (via facilitation of feedback-evoked dopamine). (C) With continued training, IL suppression of Pavlovian SSDRs is no longer necessary and PL becomes important for AR performance. This may reflect the transition of the WS from a CS that predicts harm to a DS that signals the opportunity to avoid harm (attain safety). (D) After overtraining, habit circuits gain control of ARs and performance no longer depends on amygdala, VTA or goal-directed corticostriatal circuits. Dopaminergic inputs from SNc support reinforcement of habitual associations. Note that LA, BA, IL, NAc-shell and dorsal striatum are also implicated in safety signal learning [50,54,78–81]. Both direct and indirect striatal output pathways contribute to AR performance [69,82]. Note also that latter stages of this model remain to be tested, especially the roles of DMS, DLS and IL. Abbreviations defined in text.