Researchers at Boston University may have found a way to combat age-related memory decline: brainwave synchronization. Explanations.
No matter how much we maintain it by all possible means, there always comes an age when our memory begins to fail. And our short-term memory, also called “working memory”, is the first to suffer from this neurocognitive decline.
If long-term memory is what allows us to store memories, knowledge and information, working memory is what we use constantly in our daily lives: it helps us have mental space, retain information momentarily and to process it in order to accomplish a task in progress. Whether one is affected by a neurodegenerative disease like Alzheimer’s or not, working memory naturally declines with age. This explains, for example, that a person is one day no longer able to perform certain tasks alone, such as managing their finances.
The Importance of Brainwave Synchronization
In the magazine Nature Neuroscience, researchers at the University of Boston (Massachusetts) have looked into the reasons why this working memory declines with age. They also tested different approaches to reverse this decline. “One of the main goals in the field of neurocognitive aging is to understand the brain underpinnings of working memory decline during aging, and that’s one of the goals we tried to address in this [nouveau] work,” said Robert Reinhart, director of Boston University’s Visual and Cognitive Neuroscience Laboratory.
Until now, the theory was that working memory would be the first to decline due to regions of the brain that until now had been working in sync, and would go out of sync. A key feature of this desynchronization, the researchers explain, is the disruption of brain waves – patterns of electrical activity indicating brain cell activity – that would normally coordinate. Scientists call this coordination “cross-coupling”.
More specifically, the researchers linked the maintenance of working memory to the cross-coupling of two types of brain waves, gamma and theta, in the prefrontal and temporal regions of the brain.
To confirm that theta and gamma brain waves were out of sync in older adults, the researchers monitored the brain activity of two cohorts: 42 participants aged 20 to 29 and 42 participants aged 60 to 76.
They found that on working memory tasks, older adults performed worse than younger adults. They also exhibit decoupling of theta and gamma brain waves.
A reversible desynchronization
Is this desynchronization reversible? For the researchers, it is possible that electrical brain stimulation could resynchronize the two types of waves and therefore restore the working memory capacities of the elderly. They therefore “developed an innovative neuroscience method involving non-invasive and safe stimulation of the human brain in a very specific way with extremely low electrical currents”.
This approach showed promising results: as they received brain stimulation, older participants began to perform working memory tasks better, almost as well as their younger counterparts. The researchers also found that the brain stimulation technique improved the synchronization between gamma and theta brain waves in the left temporal and prefrontal cortices. According to Pr Rheinart, this type of stimulation is able to “reconnect or resynchronize these faulty brain circuits in the brain of the elderly, and then quickly strengthen their working memory function”.
For the researchers, this discovery is important. “Not only do they give us new insights into the brain underpinnings of age-related memory decline” but they also show “that negative age-related changes are not immutable.”
They also hope that this new technique will be beneficial in the fight against neurodegenerative diseases such as Alzheimer’s.
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