Old In, New Out: The Science Behind Memory Clutter and Aging

Have you ever felt like those catchy song lyrics or random anecdotes just won’t leave your head and it’s affecting your memory? Boston University Associate Professor of Psychology and Brain Sciences Dr. Rob Reinhart and his postdoctoral associate Dr. Wen Wen address this problem in their new paper. PLOS Biology Together with their research collaborators, they are studying how mental clutter – the things we fail to forget – affects our memory as we age.

The study highlights how aging brains struggle to weed out outdated or irrelevant information, slowing down information processing and increasing the frequency of forgetfulness.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 retain relevant information. These findings not only give us a clearer picture of how memory changes with age, but also provide broader insights into cognitive health and mental well-being.

In this Q&A, Dr. Wen details the key findings of the study, explaining the importance of beta-band neuronal oscillations in memory, the impact of aging on the brain’s ability to discard irrelevant information, and what this might mean for future interventions to promote healthy cognitive aging. Wen received her Bachelor of Science from Beijing Normal University and her Doctor of Philosophy from Peking University. She studies neural plasticity and cognitive aging, with a particular focus on age-related decline in working memory.

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

Working memory is the ability to retain and manipulate information for short periods of time. It is like a mental workspace in which we temporarily store, modify, and delete 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. Although some decline is normal, significant deterioration in working memory can be associated with diseases such as dementia.

In this research, you discuss two important processes of working memory: maintenance and suppression. What are the differences between the two?

Although often thought of as a single cognitive function, working memory actually involves multiple processes. Two key processes are maintenance and suppression. Maintenance refers to the process of actively retaining and retaining information. It ensures that this information is readily available to guide our decisions and responses. Because working memory has a limited capacity, we must try to retain relevant information that is essential to decision making.

Deletion, on the other hand, involves removing obsolete or irrelevant information from working memory. This process is essential for keeping our working memory flexible and efficient. By deleting information that is no longer useful, we reduce interference from relevant information and prevent irrelevant information from cluttering our limited-capacity system. In short, 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 these and why are they important 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 call neuronal oscillations. The clustering of neuronal oscillations can be recorded in the electroencephalogram (EEG). Different frequency bands of neuronal oscillations are associated with various cognitive processes. Beta-band neuronal oscillations occur in the frequency range of 15–25 Hz. These oscillations have been well studied for their role in sensorimotor control, but they also appear to be important for the regulation of working memory.

Specifically, beta-band oscillations are thought to contribute to modulating the state of working memory contents. Although much of the existing research on beta-band oscillations comes from nonhuman animal studies, our study extends this knowledge to humans. We investigated how dynamic changes in beta-band oscillations contribute to maintaining and suppressing working memory contents.

Your research focuses on differences between young and old people. What have you learned about how age affects working memory?

We found that working memory performance in young and older adults is determined by different processes. In young adults, beta-band neuronal oscillations during the maintenance phase predicted individual memory performance.

In other words, older adults’ ability to retain information affects their working memory performance. In contrast, beta-band neuronal oscillation during the suppression phase determines working memory performance in older adults. This suggests that older adults’ ability to suppress obsolete information predicts their working memory performance. These findings support the inhibition deficit theory of aging, which states that difficulties in suppressing irrelevant information contribute to age-related cognitive decline.

Our study indicates that aging affects working memory processes differently, with suppression deficits being particularly impactful and disruptive for older adults.

How do your findings help us understand age-related cognitive decline?

The study of cognitive aging presents unique challenges, particularly when it comes to understanding complex processes like working memory, which is essential for higher-level cognitive functions. Our research delves deeper into this topic by breaking down working memory into its individual subprocesses and examining how aging affects each component.

We found that older adults face significant challenges, particularly in suppressing irrelevant information. This process, often overshadowed by research focused on maintaining cognitive function, appears to be a critical factor in cognitive decline.

The inability to effectively remove obsolete or irrelevant information creates a bottleneck in working memory. This bottleneck can impact the ability to effectively retain and process information in subsequent tasks. In other words, difficulties encountered during the removal phase can interfere with memory maintenance, highlighting the interdependence of these subprocesses.

By focusing on these distinct subprocesses, our findings offer a more nuanced understanding of cognitive decline. They suggest that interventions should not only target maintenance, but also address the specific challenges associated with suppression to more effectively support cognitive health during aging.

Are there any results from this study that surprised you?

Yes, one of the most surprising findings was the dissociation of working memory functions between young and old adults. We found distinct processes predicting working memory performance between the two age groups. For young adults, maintenance functions were key predictors of performance, while for older adults, it was the ability to suppress irrelevant information that mattered most.

In fact, we observed maintenance deficits in older adults, but these did not significantly impact their behavioral performance. This highlights the complexity of cognitive aging and suggests that our current intervention methods need to be reevaluated. This requires a more nuanced approach to understanding and treating age-related cognitive decline, focusing not only 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 underlying age-related working memory deficits opens several practical avenues, including the development of nonpharmacological interventions. While much of the current research on working memory training focuses on improving maintenance functions, our results suggest that targeting impaired suppression function could lead to more effective improvements in working memory performance in older adults.

Furthermore, our research highlights the role of beta activity as a neuronal signature of the suppression process. This discovery could pave the way for new approaches in brain training and rehabilitation. For example, non-invasive neuromodulation techniques, which are being explored in our laboratory, could potentially be used to improve or restore suppression functions in working memory by modulating neuronal oscillations in the beta band.

Who are your main research collaborators?

Members of the Reinhart lab. For this study, Shrey Grover and Rob Reinhart, in particular.