Working memory allows us to juggle different pieces of information in the short term—from remembering a grocery list while shopping to dialing a phone number after hearing it. Scientists agree that this capacity is limited, but the reasons for this have remained a matter of debate.
Now, new research from the Carney Institute for Brain Science at Brown University suggests that the limitation is not just about storage space but about learning itself. The study, published in eLife, shows that the brain’s ability to store and retrieve information is constrained by how well it can learn to manage multiple pieces of information simultaneously.
Why the Brain Can’t Hold Everything
Exploring this topic further, Dr. Michael Frank, a professor of cognitive and psychological sciences at Brown, and Aneri Soni, a graduate student in his lab, developed a computer model to understand how the brain manages working memory.
“The simulations we ran show that if we did hold more than just a few items at a time, it becomes too difficult to learn how to manage so many pieces of information at once, such that the brain gets confused and can’t use the information it does store,” Soni explained in a recent statement. “At the same time, our research demonstrates that when faced with these limitations, the brain responds by learning to strategically tap into a mechanism to help conserve space.”
That mechanism is known as “chunking”—a strategy where the brain groups related information together, compressing data to make memory more efficient. For example, instead of remembering individual digits in a phone number (5-5-5-1-2-3-4), we naturally break them into chunks (555-1234).
The concept of chunking was first established in a 2018 experiment conducted by researchers in Frank’s lab and the lab of Matt Nassar, another Brown neuroscientist. To confirm their model worked like a human brain, Soni challenged it with a version of the same experiment. She showed the model a screen with colored blocks oriented in different directions and then tested whether it could recall which block was pointing where. Over multiple trials, the model learned to group similar colors, like blue and light blue, to conserve space—just as humans do.
The Role of Dopamine in Learning and Memory
A key element of this learning process is dopamine, a neurotransmitter essential for motivation and learning. The researchers found that when the computer model successfully stored more information by chunking, its simulated dopamine system encouraged it to continue using that strategy.
To further explore dopamine’s role, Soni adjusted the model’s dopamine levels to resemble those seen in people with neurological conditions like Parkinson’s disease, ADHD, and schizophrenia. She found that in these altered models, the brain was less effective at chunking and using memory efficiently.
“Without a healthy dopamine delivery system, the model did not learn how to use its storage space as efficiently and did not chunk items as often,” Soni said.
Memory in Neurological Disorders
These findings suggest that disruptions in dopamine may contribute to memory deficits seen in people with neurological conditions.
“Take Parkinson’s disease as an example,” Frank said. “Most people think of it as a movement disorder because changes in movement are so obvious. However, it turns out that Parkinson’s patients also have changes in working memory. They are generally treated with drugs that target the prefrontal cortex, but our findings suggest that we should be testing whether drugs that target the basal ganglia and thalamus help to improve symptoms.”
This research could help refine treatments for conditions associated with dopamine dysfunction by increasing our understanding of how working memory operates in the brain. It also demonstrates the power of computational neuroscience to bridge the gap between fundamental brain science and clinical applications.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on BlueSky or contact her via email at kenna@thedebrief.org