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Related Experiment Video

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A Conflict Model of Reward-seeking Behavior in Male Rats

A Conflict Model of Reward-seeking Behavior in Male Rats

Published on: February 20, 2019

Addiction: beyond dopamine reward circuitry.

Nora D Volkow¹, Gene-Jack Wang, Joanna S Fowler

¹National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA. nvolkow@nida.nih.gov

Proceedings of the National Academy of Sciences of the United States of America

|March 16, 2011

Summary

Addiction involves dopamine (DA) system changes. Positron emission tomography (PET) studies show blunted drug responses but heightened cue responses in addicted individuals, contributing to compulsive drug use.

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Area of Science:

Neuroscience
Addiction Research
Neuroimaging

Background:

Dopamine (DA) is implicated in drug reward, but its precise role in addiction remains unclear.
Understanding the brain's DA system in addiction is crucial for developing effective treatments.

Purpose of the Study:

To review studies using Positron Emission Tomography (PET) to examine the brain's DA system in addicted individuals.
To elucidate the neurobiological mechanisms underlying compulsive drug use and loss of control in addiction.

Main Methods:

Review of human studies utilizing PET to characterize the brain DA system in subjects with addiction.
Analysis of DA release in the striatum (including nucleus accumbens) in response to drugs and drug-associated cues.

Main Results:

Addicted individuals exhibit blunted DA increases in the striatum in response to drugs compared to controls.
Drug-conditioned cues elicit significant DA increases in the striatum, associated with heightened drug craving.
Lower D2 receptor levels are observed in the striatum during withdrawal, linked to impaired executive functions.

Conclusions:

A discrepancy between expected drug effects and blunted pharmacological responses may drive continued drug-seeking behavior.
Imbalances in DA circuits for reward/conditioning versus executive control contribute to addiction's compulsivity and impulsivity.
These findings highlight disrupted dopaminergic pathways in addiction, impacting decision-making and behavioral control.