8 March 2010

Brain plasticity increased with Ritalin use

by Kate Melville

Millions of children are treated with Ritalin to improve their ability to focus on tasks, but scientists now report that Ritalin also directly enhances the speed of learning. The scientists, from the University of California - San Francisco, showed for the first time that Ritalin boosts both of these cognitive abilities by increasing the activity of the neurotransmitter dopamine deep inside the brain.

Neurotransmitters are the chemical messengers neurons use to communicate with each other. They release the molecule, which then docks onto receptors of other neurons. The research demonstrated that one type of dopamine receptor aids the ability to focus, and another type improves the learning itself. The study, appearing in Nature Neuroscience, also established that Ritalin produces these effects by enhancing brain plasticity - strengthening communication between neurons where they meet at the synapse.

"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 Antonello Bonci, principal investigator on the study.

Using animals, Bonci and his colleagues showed that Ritalin's therapeutic action takes place in a brain region called the amygdala, an almond-shaped cluster of neurons known to be critical for learning and emotional memory. "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," explained co-researcher Patricia Janak. "But we also discovered that another dopamine receptor, D1, underlies learning efficiency."

In addition, animals that performed better after Ritalin treatment showed enhanced synaptic plasticity in the amygdala. Enhanced plasticity is essentially increased efficiency of neural transmission. The researchers confirmed this by measuring electrical activity in neurons in the amygdala after Ritalin treatment. The research confirmed that learning and focus were enhanced when Ritalin was administered to animals in doses comparable to those used therapeutically in children.

By identifying the brain mechanisms underlying Ritalin's behavioral enhancements, the researchers hope to better understand the action of Ritalin as well as the properties governing brain plasticity.

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Source: University of California - San Francisco