Role of Dopamine in Reward-Related Learning

Pleasurable rewards can reinforce behaviors.

Dopamine is an important neurotransmitter that plays a large role in addiction, pain and pleasure, as well as motor ability. Experiments link dopamine to the reinforcement of learned behaviors.

Reward-Based Reinforcement

When an animal receives a reward such as food, dopamine is released in the brain. If such an experience follows a task being taught, the pleasurable experience becomes associated with successful completion of the task, motivating the animal to learn the task well in hopes of receiving future rewards. However, dopamine doesn't provide pleasure as such--it motivates the learner to consider certain things more important than others.

Priming

Giving a "free" reward before a task is called priming. The reinforcement effect of the freebie decays quickly and isn't stored in long-term memory, whereas the effects of the post-task reward are. Dopamine is involved in both cases.

Effects of Dopamine Antagonists

Dopamine antagonists block the reception of dopamine. If animals are given dopamine antagonists before completing a task, their performance at the task diminishes significantly over time. The animal remembers that completing the task didn't provide the pleasure it did in the past, and so the motivation to perform is gradually lost.

References

• University of Texas Addiction Science and Resource Center: Dopamine: A Sample Neurotransmitter
• Nutritional Blogma: L-DOPA (dopamine) and subjective hedonic expectation
• Ohio State University: Neurobiology of Disease: Dopamine, learning and motivation (review)