Medications like Adderall and Ritalin have helped thousands of patients with attention problems improve their grades, focus at work and function better at home — but the nitty-gritty neural processes that that make these drugs effective are not clearly understood.
New neuroscience research from the University of Pittsburgh sheds light on how two seemingly different brain processes related to attention are more similar than previously thought, which could someday lead to improved targets for drug researchers.
Pitt associate professor of neuroscience Marlene Cohen and Amy Ni, a postdoctoral researcher in the Department of Neuroscience, want to understand how people make sense of the world when they open their eyes. Somehow, they’re able to pick out the important or relevant parts of a scene, like a friend in a crowd — how?
Earlier this year, Cohen’s lab published a paper in the journal Science about a small but fundamental piece of this puzzle. The team wanted to see what goes on at the neural level when the brain practices detecting differences in visual stimuli thousands of times, a process called perceptual learning.
A common example of perceptual learning is when a radiologist spends day after day looking at X-rays for slight indications of a tumor or fluid buildup. Compared to the relatively simple task of picking a friend out from a crowd —in other words, simply paying attention — identifying a tumor involves calling up memories from pathology slides during medical school, past experiences with patients and synthesizing other long-term knowledge in the context of the x-ray at hand.
“With perceptual learning, adults can improve their vision by practicing a visual task over many repetitions. It's the reason a trained radiologist can spot tiny imperfections in an X-ray the rest of us can't see, or an expert bird watcher can see the difference between two species of birds that look almost identical,” Ni said.
Before Ni and Cohen published their paper in Science, researchers wavered over whether the brain activity behind spotting a friend in a crowd and learning to spot a tumor on an X-ray, for example, were actually similar, as both function to help improve vision.
The big news now, Ni said, is that through tracking how neurons respond to visual stimuli, the research found that groups of neurons do in fact behave similarly, whether they’re briefly focusing on something — paying attention — or have been trained to recognize something for a long time through perceptual learning.
“Attention helps us focus our vision on specific parts of a crowded scene, and it is the reason we can spot someone faster when we know where they're located or what color shirt they're wearing,” she said.
Knowing that the brain uses the same processes for attention and for perceptual learning is “evidence that this mechanism is important for vision, regardless of timescale,” Ni said.
Cohen, who was one of two researchers nationally to receive a Troland Research Award from the National Academy of Sciences this year, said that the “result is one of many recent findings that suggest that measuring the relationship between populations of neurons and behavior will be key to unlocking many mysteries of the brain."
Ni and Cohen stress that this work is very far from the clinic, but it has real potential to clarify exactly how attention-altering drugs help people with ADHD focus. By understanding the best way to convey visual information on a cellular level, researchers can begin to understand exactly how these drugs work.
Ni added this provides exciting hypotheses for future work: Maybe all processes that improve our vision do so using a common mechanism, which could be targeted by even more precise attention-enhancing medications.
The study was supported by the Simons Foundation through a grant awarded to Cohen and a fellowship awarded to Ni, as well as funding from the National Institutes of Health.