Doctors treat millions of children with Ritalin every year to improve their ability to focus on tasks, but scientists now report that Ritalin also directly enhances the speed of learning.
In animal research, the scientists 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 scientists also established that Ritalin produces these effects by enhancing brain plasticity - strengthening communication between neurons where they meet at the synapse. Research in this field has accelerated as scientists have recognized that our brains can continue to form new connections - remain plastic - throughout life.
"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, MD, principal investigator at the Ernest Gallo Clinic and Research Center and professor of neurology at UCSF. The Gallo Center is affiliated with the UCSF Department of Neurology.
Bonci is co-senior author of the paper, which will be published online in "Nature Neuroscience" on Sunday, March 7, 2010.
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," said Patricia Janak, PhD, co-senior author on the paper. "But we also discovered that another dopamine receptor, D1, underlies learning efficiency."
Janak is a principal investigator at the Gallo Center and a UCSF associate professor of neurology. Lead author of the paper is Kay M. Tye, PhD, a postdoctoral scientist at the Gallo Center when the research was carried out.