Gene-Jack Wang

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The ability of drugs of abuse to increase dopamine in nucleus accumbens underlies their reinforcing effects. However, preclinical studies have shown that with repeated drug exposure neutral stimuli paired with the drug (conditioned stimuli) start to increase dopamine by themselves, which is an effect that could underlie drug-seeking behavior. Here we test(More)
Imaging studies have revealed neurochemical and functional changes in the brains of drug-addicted subjects that provide new insights into the mechanisms underlying addiction. Neurochemical studies have shown that large and fast increases in dopamine are associated with the reinforcing effects of drugs of abuse, but also that after chronic drug abuse and(More)
Imaging studies have provided evidence of how the human brain changes as an individual becomes addicted. Here, we integrate the findings from imaging studies to propose a model of drug addiction. The process of addiction is initiated in part by the fast and high increases in DA induced by drugs of abuse. We hypothesize that this supraphysiological effect of(More)
The ability to resist the urge to eat requires the proper functioning of neuronal circuits involved in top-down control to oppose the conditioned responses that predict reward from eating the food and the desire to eat the food. Imaging studies show that obese subjects might have impairments in dopaminergic pathways that regulate neuronal systems associated(More)
CONTEXT Modafinil, a wake-promoting drug used to treat narcolepsy, is increasingly being used as a cognitive enhancer. Although initially launched as distinct from stimulants that increase extracellular dopamine by targeting dopamine transporters, recent preclinical studies suggest otherwise. OBJECTIVE To measure the acute effects of modafinil at doses(More)
Drug addiction is characterized by a set of recurring processes (intoxication, withdrawal, craving) that lead to the relapsing nature of the disorder. We have used positron emission tomography to investigate in humans the role of dopamine (DA) and the brain circuits it regulates in these processes. We have shown that increases in DA are associated with the(More)
HIV has a propensity to invade subcortical regions of the brain, which may lead to a subcortical dementia termed HIV-cognitive motor complex. Therefore, we aimed to assess whether dopamine (DA) D2 receptors and transporters (DAT) are affected in the basal ganglia of subjects with HIV, and how these changes relate to dementia status. Fifteen HIV subjects(More)
Drugs and food exert their reinforcing effects in part by increasing dopamine (DA) in limbic regions, which has generated interest in understanding how drug abuse/addiction relates to obesity. Here, we integrate findings from positron emission tomography imaging studies on DA's role in drug abuse/addiction and in obesity and propose a common model for these(More)
Cocaine cues elicit craving and physiological responses. The cerebral circuits involved in these are poorly understood. The purpose of this study was to assess the relation between regional brain activation and cocaine cue elicited responses. Thirteen right-handed cocaine abusers were scanned with positron emission tomography (PET) and [F-18](More)
Methylphenidate hydrochloride (MP) is an effective treatment for attention-deficit/hyperactivity disorder (ADHD), a common neurobehavioral disorder of childhood onset characterized by inattention, hyperactivity, and distractibility. Methylphenidate hydrochloride blocks the dopamine transporters (DAT), the main mechanism for removing dopamine (DA) from the(More)