Introduction: Natural rewards are essential for survival. However, drug-seeking behaviors can be maladaptive and endanger survival. The present study was conducted to enhance our understanding of how animals respond to food and morphine as natural and drug rewards, respectively, in a conditioned place preference (CPP) paradigm. Methods: We designed a protocol to induce food CPP and compare it ...

Conditional responses in rodents such as locomotion have been reported for drugs of abuse and similar to the placebo response in humans, may be associated with the expectation of reward. We examined several conditional opioid-like responses and the influence of drug expectation on conditioned place preference and concomitant conditional locomotion. Male C57BL/6J mice were conditioned with the s...

Vulnerability to nicotine addiction is significantly increased in individuals who begin smoking during adolescence; however, the underlying mechanisms of this phenomenon remain unclear. This study examined the motivational effects of nicotine withdrawal in adolescent (PND 27-42) and adult (PND 60-75) rats using the conditioned place aversion paradigm. Male Wistar rats were tested for their init...

The dopaminergic innervation of the nucleus accumbens (NAc) is implicated in the selection and integration of motivationally relevant corticolimbic information that governs behavioral output. However, it is unknown whether the dopaminergic innervations of two anatomically distinct subregions of the NAc, core and shell, have differential roles in this gating process, and whether dopaminergic mec...

The discovery that delta-9-tetrahydrocannabinol (Δ(9)-THC) is the primary psychoactive ingredient in marijuana prompted research that helped elucidate the endogenous cannabinoid system of the brain. Δ(9)-THC and other cannabinoid ligands with agonist action (CP 55,940, HU210, and WIN 55,212-2) increase firing of dopamine neurons and increase synaptic dopamine in brain regions associated with re...

Latent inhibition (LI) is the proactive interference of repeated nonreinforced preexposure to a stimulus with subsequent performance on a learning task involving that stimulus. The present experiments investigated the role of the nucleus accumbens (NAC) in LI. LI was measured in a thirst motivated conditioned emotional response procedure with low or high number of conditioning trials, and in tw...