Role of dorsal hippocampus in cocaine cue and contextual memory reconsolidation (2013)

Undergraduates: Keona Perry, Kati Healey Xiaohu Xie

Faculty Advisor: Rita Lokensgard
Department: Psychology & Neuroscience

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Environmental cues and contexts illicit drug craving in dependent individuals and increases the odds of relapse. Disruption of cue memories has been shown to disable drug-seeking behavior. The dorsal hippocampus (DH) is involved in the reconsolidation of contextual cocaine memories that trigger reinstatement of cocaine seeking. Prior research has focused on contextual cues or discrete cues in drug seeking behaviors, but not on the connection between drug-paired contextual cue and discrete cue memories. We hypothesized that reactivating the cocaine context and disrupting memory reconsolidation of the context, will disrupt the memory of the cocaine-paired cue. To test our hypothesis, rats were trained to lever press for cocaine infusions and a response contingent cue in a distinct context. Then, cocaine seeking was extinguished in a distinctly different context. Rats were briefly re-exposed to the cocaine-paired context, and were immediately microinfused with baclofen/mucimol (B/M) or vehicle (PBSO). Then, we tested for the reinstatement of cocaine seeking in the presence of the context and the cue separately. Pharmacological lesioning of the DH following re-exposure to the cocaine context impaired subsequent drug context-induced cocaine-seeking behavior in the presence of the context alone, but not the cue alone. Thus, contextual and discrete cues are not linked in the DH, and disruption of reconsolidation of the context will not disrupt memories of the drug-paired cue.