How Ritalin Increases Attention – Neuroscience News

summary: The study sheds new light on the neurobiological mechanisms that occur, allowing the ADHD drug Ritalin to improve attention and report benefits of the drug for a range of cognitive changes associated with aging.

source: University of Pittsburgh

Even half a century after a drug came to market, scientists can still learn new things about how it works. New research by neuroscientists at the University of Pittsburgh offers a rare look at how Ritalin affects activity in animals’ brains, providing a deeper understanding of how groups of brain cells control attention and pointing to potential new uses for the stimulant.

About 1 in 11 children in the United States are prescribed stimulants such as methylphenidate (also known by its brand name Ritalin) to improve attention and focus in people with attention-deficit/hyperactivity disorder or ADHD.

Many adults, estimated to be 1 in 5 according to surveys, also use off-label medications. And although the safety and effectiveness of these drugs is well understood, there is still much to learn about how they work.

“We really know very little about what these drugs do to the activity of populations of neurons,” said senior study author Marlene Cohen, professor of neuroscience at the Kenneth P. Dietrich College of Arts and Sciences.

“But basic scientists like us have been investigating which groups of neurons can tell us about behavior and cognition, so understanding what these drugs do to groups of neurons can give us hints about other things that might be useful for them.”

Previous work led by Pitt postdoctoral researcher Amy Ni has shown a link between animals performing well on a visual task and a specific measurement of neurons in the visual cortex — specifically, how likely they are to fire independently of each other, rather than synchronously.

In the current work, they found that animals given methylphenidate performed better on a visual attentional task, and that the improvement occurred exactly when the same measure of neuronal activity changed.

The team led by Ni published their research in the journal Proceedings of the National Academy of Sciences On April 25th.

Some of the study results were predictable from what is already known about the drug. All three animals took methylphenidate or a placebo on successive days for two weeks of testing. On the days they took the medication, they spent more time on the task and performed better on it, but only when the required task occurred in a place they were actually paying attention to.

In most neuroscience experiments, researchers target very small groups of neurons with electricity or light. “We definitely didn’t — we took these drugs, mixed them into fruit juice, and gave them to the animals,” Cohen said. “It struck me that a very general manipulation would have a very specific behavioral effect.”

Besides learning more about how the drug works, experiments like this allow researchers to gain a broader understanding of how neuron firing patterns translate into behaviors such as paying attention to what we see.

By comparing how neurons function when the brain is in different states — such as when a person takes a drug versus when they don’t — researchers can create more complete and useful models of how brain cells relate to behavior.

It’s an approach that has not received much attention, Cohen said, in part because of a lack of ways to fund research on how drugs alter neuronal activity. This makes it difficult to research “cross-therapies,” that is, new uses for drugs already on the market.

This is a diagram of a head surrounded by bubbles
About 1 in 11 children in the United States are prescribed stimulants such as methylphenidate (also known by its brand name Ritalin) to improve attention and focus in people with attention-deficit/hyperactivity disorder or ADHD. The image is in the public domain

In light of the current study, previous in vitro work points to some of these potential crossovers. Ni’s research has found similarities between the neural patterns associated with attention and certain types of learning, suggesting that treatments for disorders involving one may be effective for the other.

“These stimulants may actually be useful for treating a lot of things, from cognitive changes associated with normal aging, to Alzheimer’s disease and more,” Cohen said. Although at the moment it is only an informed hunch, it is one of the plans that the laboratory plans to pursue in future studies.

For now, this study remains an important first step in a series of research that Cohen hopes to see more of: connecting the dots between the neural underpinnings of our behavior and how drugs affect them.

“It’s one test case, and I think there’s a lot that needs to be done,” she said. “I hope people will see that these methods are important.”

About this psychopharmacology and research interest news

author: press office
source: University of Pittsburgh
Contact: Press Office – University of Pittsburgh
picture: The image is in the public domain

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Methylphenidate as a causal test of hypotheses for basic neuronal coding and translationWritten by Aimee M. Ni et al. PNAS

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Methylphenidate as a causal test of hypotheses for basic neuronal coding and translation

Most studies of systems neuroscience fall into two categories: basic science work aimed at understanding the relationship between neurons and behavior, or localized work aimed at developing treatments for neuropsychiatric disorders.

Here we use these two approaches to inform and reinforce each other.

Our study tests hypotheses about basic science neural coding principles and elucidates the neural mechanisms underlying the clinically relevant behavioral effects of methylphenidate (Ritalin).

We discovered that orally administered methylphenidate, used clinically to treat attention deficit hyperactivity disorder (ADHD) and in general to enhance cognition, increases spatially selective visual attention, and enhances visual performance in the supervised location only.

Furthermore, we found that this causal manipulation enhances vision in rhesus macaques specifically when it reduces the average correlated variance of neurons in the V4 visual area. Our findings demonstrate that the visual system is a platform for understanding the neural underpinnings of both complex cognitive processes (basic science) and neuropsychiatric disorders (translation).

Addressing basic science hypotheses, our results are consistent with a scenario in which methylphenidate has cognitively specific effects by acting through naturally selective cognitive mechanisms.

Clinically, our findings suggest that surprisingly often specific symptoms of neuropsychiatric disorders can be caused and treated by making use of general mechanisms.