- The neurotransmitter that plays a central role in the brain's reward circuitry involved in addiction is Dopamine.
- Dopamine is critically involved in the regulation of pleasure, motivation, and reinforcement learning.
- When addictive substances or behaviors stimulate the release of dopamine in areas such as the nucleus accumbens and the ventral tegmental area (VTA), it creates a sensation of reward and euphoria, reinforcing the behavior and increasing the likelihood of repetition.

- While other neurotransmitters like serotonin, GABA, and acetylcholine have important roles in brain function, they are not the primary mediators of the reward pathways associated with addiction.
- For example, serotonin is more involved in mood regulation, GABA primarily functions as an inhibitory neurotransmitter, and acetylcholine is crucial for attention and memory processes.

In summary, dopamine's role in the mesolimbic pathway underlies the reinforcing properties of addictive substances and behaviors, making it the central neurotransmitter in addiction mechanisms.

Reference: Principles of Neural Science, 5th Edition, Volume 1, Chapter 49