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Dopamine release within the nucleus accumbens (NAcc) has been associated with both the rewarding and locomotor-stimulant effects of abused drugs. The functions of the NAcc core and shell were investigated in mediating amphetamine-potentiated conditioned reinforcement and locomotion. Rats were initially trained to associate a neutral stimulus (Pavlovian CS)(More)
Only recently have the functional implications of the organization of the ventral striatum, amygdala, and related limbic-cortical structures, and their neuroanatomical interactions begun to be clarified. Processes of activation and reward have long been associated with the NAcc and its dopamine innervation, but the precise relationships between these(More)
Drug addiction can be considered an impulse control disorder in that addicts exhibit increased impulsivity on both behavioural and self-report measures. We investigated whether chronic cocaine affects delay of gratification and/or behavioural disinhibition in rats using the delayed reinforcement and Go/No-go paradigms. Animals were treated with saline or(More)
Experiment 1 examined whether microinjections of morphine (1 microg in 0.5 microl over 1 min x 2 pairings) into 13 different CNS sites produced a conditioned place preference (CPP). Injections into the lateral ventricles (LV), ventral tegmental area (VTA), or periaqueductal gray (PAG) produced a CPP; injections 1 mm dorsal to the PAG or VTA, or into the(More)
Sustained attention requires the integrity of basal forebrain cholinergic systems. The pedunculopontine tegmental nucleus (PPTg) has direct and indirect connections (via the thalamus) with the basal forebrain, suggesting that the PPTg may also play an important role in attentional processes. We examined this hypothesis by testing the effects of PPTg lesions(More)
Compulsion and impulsivity are both primary features of drug addiction. Based on decades of animal research, we have a detailed understanding of the factors (both environmental and physiological) that influence compulsive drug use, but still know relatively little about the impulsive aspects of drug addiction. This review outlines our current knowledge of(More)
Clinical reports and animal experiments indicate that both cocaine administration and cocaine withdrawal increase anxiety. We investigated the ability of a number of putative anxiolytic agents to alleviate these anxiety states using the elevated plus-maze. Rats in the cocaine condition received either saline or cocaine (20 mg/kg) 40 min prior to testing;(More)
In two experiments rats were trained to self-administer intravenous cocaine on chained schedules using different responses in the initial (drug-seeking) and terminal (drug-taking) links. In both between- (Experiment 1) and within-subject designs (Experiment 2), the drug-taking response was then either extinguished or reinforced in the absence of the(More)
Rationale: In animal models of drug self-administration, response rates often decrease with dose suggesting that a regulative process may mask the reinforcing effects of the drug. Objective: The purpose of the present experiments was to dissociate the role of regulative and reinforcement processes in intravenous cocaine self-administration by rats using a(More)
Opioid agonists such as morphine have been found to exert excitatory and inhibitory receptor-mediated effects at low and high doses, respectively. Ultra-low doses of opioid antagonists (naloxone and naltrexone), which selectively inhibit the excitatory effects, have been reported to augment systemic morphine analgesia and inhibit the development of(More)