Research reported by scientists from the University of California-San Francisco (UCSF) has shown that, in a rat model, Ritalin (methylphenidate) boosts both the ability to focus on tasks and the speed of learning by increasing the activity of the neurotransmitter dopamine through mechanisms involving two distinct dopamine receptors in the amygdala region of the brain. "We found that a dopamine receptor, known as the D2 receptor, controls the ability to stay focused on a task--the well-known benefit of Ritalin," said Dr. Patricia Janak, co-senior author of the paper. "But we also discovered that another dopamine receptor, D1, underlies learning efficiency." "Since we now know that Ritalin improves behavior through two specific types of neurotransmitter receptors, the finding could help in the development of better targeted drugs, with fewer side effects, to increase focus and learning," said Dr. Antonello Bonci, the other co-senior author of the article. The research assessed the ability of rats to learn that they could get a sugar water reward when they received a signal--a flash of light and a sound. The scientists compared the behavior of animals receiving Ritalin with those that did not receive it, and found those receiving Ritalin learned much better. However, they also found that if they blocked the dopamine D1 receptors with drugs, Ritalin was unable to enhance learning. And if they blocked D2 receptors, Ritalin failed to improve focus. The experiments established the distinct role of each of the dopamine receptors in enabling Ritalin to enhance cognitive performance.
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