Relapse is the single greatest barrier to recovery from addiction. Long-term memories for drug experience and associated contextual cues can provoke craving and resumption of drug use, particularly when a reminder of a highly charged context is encountered. In this thesis, three key questions related to the maintenance of long-term memory for drug-associated contexts are addressed: (1) Are Pavlovian conditioned associations between cocaine experience and the context in which it occurred maintained in long-term memory after extended periods of abstinence? (2) Are regions of the mesocorticolimbic circuitry, namely the nucleus accumbens and amygdala, differentially activated by retrieval of Pavlovian conditioned associations as time passes after cocaine experience? (3) Do neurons of the nucleus accumbens and amygdala show changes in dendritic architecture that reflect the impact of chronic cocaine exposure, which may underlie the maintenance of Pavlovian and/or instrumental drug-conditioned associations? Results confirm that Pavlovian conditioned memory for a cocaine-associated context is maintained in the long-term, becoming increasingly resilient over time. However, maintenance of these contextual associations is not accompanied by gross changes in dendritic architecture in neurons of the nucleus accumbens or amygdala within the timeframe examined. Nonetheless, these brain regions, along with the prefrontal cortex, are differentially activated by retrieval of Pavlovian conditioned associations after brief versus extended periods of abstinence. Together, these results emphasize a distinct contribution of Pavlovian memory processes, beyond instrumental and operant drug memory processes, in the long-term maintenance of addiction.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/65673 |
| Date | 22 July 2014 |
| Creators | Johnson, Sarah Anne |
| Contributors | Erb, Suzanne |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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