Out with the old, in with the new: the science behind memory clutter and aging

Ever feel like those catchy song lyrics or random pieces of trivia won’t leave your head, and it’s affecting your memory? Boston University associate professor of psychological & brain sciences Dr. Rob Reinhart, along with his postdoctoral associate, Dr. Wen Wen, dive into this issue in their new PLOS Biology study. Together with their research collaborators, they explore how mental clutter — the stuff we can’t seem to forget — affects our memory as we get older.

The research highlights how aging brains struggle to clear out outdated or irrelevant information, leading to slower processing and more frequent forgetfulness. The study identifies a specific brain pattern — beta frequency variability — that predicts memory performance in older adults, while younger adults show a stronger link between memory and their ability to hold onto relevant information. These findings not only give us a clearer picture of how memory changes with age but also point to broader insights into cognitive health and mental well-being.

In this Q&A, Dr. Wen breaks down the study’s key findings, explaining the significance of beta-band neural oscillations in memory, how aging impacts the brain’s ability to let go of irrelevant information, and what this could mean for future interventions to support healthy cognitive aging. Wen received her Bachelor of Science from Beijing Normal University and Doctor of Philosophy from Peking University. She studies neural plasticity and cognitive aging, with a particular focus on age-related working memory decline.

What is “working memory” and why is it important?

Working memory is the ability to hold and manipulate information over short periods. It’s like a mental workspace where we temporarily keep, edit and remove data to achieve our goals. This cognitive ability is crucial because it helps us perform tasks that require reasoning, problem-solving and planning. However, as we age, working memory tends to decline. While some decline is normal, significant deterioration in working memory can be associated with conditions like dementia.

In this research, you talk about two important working memory processes: maintenance and deletion. What are the differences between the two?

While often referred to as a single cognitive function, working memory actually involves multiple processes. Two key processes are maintenance and deletion. Maintenance refers to the process of actively keeping and holding information. It ensures that this information is readily available to guide our decisions and responses. Because working memory has a limited capacity, we should try to maintain relevant information that is essential for decision-making. Deletion, on the other hand, involves removing outdated or irrelevant information from working memory. This process is vital for keeping our working memory flexible and efficient. By deleting information that is no longer useful, we reduce interference of pertinent information and prevent irrelevant information from cluttering our capacity-limited system. In summary, while maintenance helps us keep relevant information accessible, deletion ensures that irrelevant information is removed to avoid cognitive overload.

The study also mentions, “beta-band neural oscillations.” What are those, and why are they significant for working memory?

Neurons are the primary units of brain communication. When populations of neurons are excited or inhibited, rhythmic patterns of activity emerge, which we refer to as neural oscillations. Grouping of neural oscillations can be recorded in electroencephalogram (EEG). Different frequency bands of neural oscillations are associated with various cognitive processes. Beta-band neural oscillations occur in the frequency range of 15–25 Hz. These oscillations have been well-studied for their role in sensorimotor control, but they are also emerging as important for regulating working memory. Specifically, beta-band oscillations are thought to help modulate the status of working memory contents. Although much of the existing research on beta-band oscillations comes from studies in non-human animals, our study extends this knowledge to humans. We investigated how the dynamic changes of beta-band oscillations help to maintain and delete the contents in working memory.

Your research looks at differences between younger and older adults. What did you learn about how age affects working memory?

We found that working memory performance of younger and older adults are determined by different processes. For younger adults, beta-band neural oscillations during the maintenance stage predicted individual memory performance. In other words, how well they could hold the information affects working memory performance. In contrast, beta-band neural oscillation during the deletion phase determined working memory performance for older adults. This suggests that older adults’ ability to delete outdated information predicts their working memory performance. These findings support the inhibition deficit theory of aging, which says that difficulties in deleting unnecessary information contribute to age-related cognitive decline. Our study indicates that aging affects working memory processes differently, with deletion deficits being particularly impactful and disruptive for older adults.

How do your findings help us understand cognitive decline as we age?

Studying cognitive aging presents unique challenges, especially when it comes to understanding complex processes like working memory, which is crucial for higher-level cognitive functions. Our research delves into this by breaking down working memory into its individual subprocesses and examining how aging affects each component. We discovered that older adults face significant challenges specifically with the deletion of irrelevant information. This process, often overshadowed by research focusing on maintenance, appears to be a critical factor in cognitive decline.

The inability to efficiently remove outdated or irrelevant information creates a bottleneck in working memory. This bottleneck can impact the ability to maintain and process information effectively in subsequent tasks. In other words, difficulties in the deletion phase can interfere with memory maintenance, highlighting how these subprocesses are inter-dependent. By focusing on these distinct subprocesses, our findings provide a more nuanced understanding of cognitive decline. They suggest that interventions should not only target maintenance but also address the specific challenges associated with deletion to more effectively support cognitive health in aging.

Were there any findings in this study that surprised you?

Yes, one of the most surprising findings was the dissociation in working memory functions between younger and older adults. We discovered distinctive processes predicting working memory performance between the two age groups. For younger adults, maintenance functions were key predictors of performance, while for older adults, it was the ability to delete irrelevant information that mattered most. In fact, we did observe maintenance deficits in older adults; these did not have a significant impact on their behavioral performance. This emphasizes the complexity of cognitive aging and suggests that our current methods of intervention may need to be re-evaluated. It calls for a more nuanced approach to understanding and addressing age-related cognitive decline, focusing not just on general cognitive functions but also on specific processes that are differentially affected by aging.

What practical implications could this research have?

Understanding the mechanisms behind age-related working memory deficits opens up several practical avenues, especially for developing non-pharmacological interventions. While much of the current research on working memory training has focused on improving maintenance functions, our findings suggest that targeting the impaired deletion function could lead to more effective improvements in working memory performance for older adults. Additionally, our research highlights the role of beta activity as a neural signature for the deletion process. This insight could pave the way for new approaches in brain training and rehabilitation. For example, non-invasive neuromodulation techniques, which are being explored in our lab, could potentially be used to enhance or restore the deletion functions in working memory by modulating beta-band neural oscillations.

Who are your key research collaborators?

Reinhart Lab members. For this study, Shrey Grover and Rob Reinhart, in particular.