||Drug relapse is a serious, social issue that requires extensive research in order to understand the mechanisms that precede relapse. Craving, the intense desire for a specific object or experience, is an important component of relapse. Drug-associated environmental cues (drug paraphernalia or locations where a drug was previously consumed) can elicit cravings and subsequently cause a return to previous behavior. Visual-spatial pattern completion (dorsal CA3 subregion of the hippocampus), a process wherein presentation of an incomplete stimulus complex reinstates the complete, previously learned pattern, is a novel mechanism to explain this observation. In this experiment, seven rats were handled daily for a week, following a baseline preference test (day 1). Rats were placed in one of two compartments of a Plexiglas box. Each compartment contained four different cues (two sets of cues). The non-preferred side was paired with cocaine (15mg/kg, intraperitoneal), while the preferred side was paired with phosphate buffered saline (lmL/kg, i.p). The order of the pairing (cocaine or saline first) was counterbalanced across treatment groups (days 2-9). Day 10 preference tests showed a strong preference for the cocaine-associated objects. Animals were then maintained for 21 days during abstinence. Four preference tests were given (days 32, 36, 40, 44) where animals were tested for one or four-cue environments with saline or naloxone (3mg/kg, i.p). The goal of this proposal was to use a variation of the conditioned place preference task to determine how the number of cues interacts with the role of visual-spatial pattern completion, and subsequently drug-seeking behavior. Also, the experiment sought to determine the effects of naloxone on cue-induced reinstatement. Results indicated that naloxone successfully disrupted visualspatial pattern completion for both one and four cues. Systemic injection is routinely used within the human population, and is a very accessible form of relapse prevention among recovering drug addicts.