The role of the basolateral amygdala in stimulus–reward memory and extinction memory consolidation and in subsequent conditioned cued reinstatement of cocaine seeking

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Abstract
The consolidation of cue–cocaine associations and extinction learning (i.e. cue–no cocaine associations) into long‐term memory probably regulates the long‐lasting control of conditioned stimuli (CS) over cocaine‐seeking behaviour, and the basolateral amygdala (BLA) may play a role in this phenomenon. To test this hypothesis, rats previously trained to self‐administer cocaine underwent a single classical conditioning (CC) session, during which they received passive pairings of cocaine infusions and a novel light + tone stimulus complex. After additional self‐administration sessions in the absence of CS presentation and subsequent extinction training sessions, the ability of the CS to reinstate cocaine‐seeking on five test days was assessed. Rats received intra‐BLA microinfusions of vehicle or the Na+‐channel blocker tetrodotoxin (TTX) immediately after CC (consolidation of CS–cocaine associations) or immediately after reinstatement testing (consolidation of extinction learning). TTX administered immediately after CC attenuated subsequent CS‐induced reinstatement. In contrast, TTX administered after the first reinstatement test impaired the extinction of cocaine‐seeking behaviour during a second reinstatement test by disrupting extinction memory. Overall, these findings suggest that Na+ channel‐mediated mechanisms within the BLA mediate the consolidation of both cocaine–stimulus association and extinction learning, two processes that have opposite effects on subsequent cue‐induced cocaine‐seeking behaviour.