Aberrant approach-avoidance conflict resolution following repeated cocaine pre-exposure.

RATIONALE: Addiction is characterized by persistence to seek drug reinforcement despite negative consequences. Drug-induced aberrations in approach and avoidance processing likely facilitate the sustenance of addiction pathology. Currently, the effects of repeated drug exposure on the resolution of conflicting approach and avoidance motivational signals have yet to be thoroughly investigated.
OBJECTIVE: The present study sought to investigate the effects of cocaine pre-exposure on conflict resolution using novel approach-avoidance paradigms.
METHODS: We used a novel mixed-valence conditioning paradigm to condition cocaine-pre-exposed rats to associate visuo-tactile cues with either the delivery of sucrose reward or shock punishment in the arms in which the cues were presented. Following training, exploration of an arm containing a superimposition of the cues was assessed as a measure of conflict resolution behavior. We also used a mixed-valence runway paradigm wherein cocaine-pre-exposed rats traversed an alleyway toward a goal compartment to receive a pairing of sucrose reward and shock punishment. Latency to enter the goal compartment across trials was taken as a measure of motivational conflict.
RESULTS: Our results reveal that cocaine pre-exposure attenuated learning for the aversive cue association in our conditioning paradigm and enhanced preference for mixed-valence stimuli in both paradigms.
CONCLUSIONS: Repeated cocaine pre-exposure allows appetitive approach motivations to gain greater influence over behavioral output in the context of motivational conflict, due to aberrant positive and negative incentive motivational processing.