Another level to this complexity are findings indicating that dopamine release and NAc cell firing that occur within seconds of the response represent associative aspect of the task, not a direct pharmacological action of cocaine. For example, we have shown that both dopamine release and phasic accumbens neuronal responses are not evident within seconds following experimenter delivered cocaine delivery but are selectively activated by the tone-houselight stimulus paired with cocaine infusion during self-administration (Carelli & Deadwyler, 1996; Carelli, 2000; Phillips et al., 2003b). This same activation is absent in animals without a history of cue-drug pairings (Phillips et al., 2003b; Hollander & Carelli, 2007). In addition, we have shown that NAc cell firing and dopamine release are also influenced by instrumental contingencies (i.e., lever press requirement) implicit in the behavioral task since post response activity can be extinguished and reinstated (Carelli & Ijames, 2000; Stuber et al., 2005b) these findings support the view that although cocaine clearly has direct pharmacological actions that occur over a longer time period (e.g., (Peoples & West, 1996; Stuber et al., 2005b; Aragona et al.,
