Memory saved? Stimulates the brain or helps improve memory

Original author: Diana Kwon

After 4 days of noninvasive electrical stimulation, the participants were able to better recall information
for up to a month.

Human memory fades with age — but one day, researchers may be able to combat this trend
in a simple, drug-free way.

According to a study published August 22 in Nature Neuroscience,[1] Robert Reinhart, a cognitive neuroscientist at Boston University, and colleagues showed that repeated stimulation of the brains of adults over the age of 65 with a weak electric current for several days led to memory improvements
that lasted up to a month.

Different types of memories are controlled
by different brain regions.

Previous research has shown that long-term memory and "working" memory (which allows the brain to temporarily store information) are controlled by different brain regions
.

Building on this study, the team demonstrated that stimulation of the dorsolateral prefrontal cortex (an area near the front of the brain) with high-frequency currents improves long-term memory, while low-frequency current stimulation of the lower lobis (later in the brain) improves working memory
.

"Their results look promising," said Ines Violante, a neuroscientist
at the University of Surrey in the UK.

"They really took advantage of the knowledge accumulation
in this field.

”

Memory improvement

Reinhart's team conducted a series of experiments
on 150 people between the ages of 65 and 88 using a non-invasive method of brain stimulation called transcranial alternating current stimulation (tACS), which provides electricity through electrodes on the surface of the scalp.

Participants performed a memory task in which they were asked to memorize a list of many words read aloud by an experimenter, each with 20 words
.

Brain stimulation occurs throughout the task, about 20 minutes
.

After receiving the protocol for 4 consecutive days, subjects who received high-frequency stimulation in the dorsolateral prefrontal cortex improved their ability to memorize words at the beginning of the list, a task that relies on long-term memory; Low-frequency stimulation of the lower leaflets improved participants' ability to memorize words at the bottom of the list, which involved working memory
.

Participants' memory performance improved within 4 days – and these benefits continued even after
a month.

Those who had the lowest general cognitive performance before the study began, had the greatest
improvement in memory.

Altering the frequency and brain regions (such as applying high-frequency stimulation of the parietal lobe), or using a "pseudo" scheme (briefly applying an electric current at the beginning and end of a task to simulate the sensation of brain stimulation), did not improve memory
.

Convincing

"I was surprised and impressed
by the paper.

Simon Hanslmayr, a cognitive neuroscientist at the University of Glasgow in the UK, said
.

Like other scientists, he notes, he has been skeptical
about whether tACS can bring about meaningful cognitive change.

One problem is that tACS devices produce much less current than other methods of stimulating the brain, so it's never clear whether they can transmit enough electricity
to the brain to change its function.

But the study's authors convincingly show that their protocol can be linked to "sustained and fairly strong memory improvement," Hanslmayr said
.

He added that there are places that make the study unique
.

One is that the authors applied tACS for several consecutive days – past studies have typically only been done once; The other was that the experiment included people over the age of 65, while most of the other studies were young, memory-good students
.

These factors, he said, may help explain why the authors were able to produce these compelling results
.

There are still some problems
left here.

Co-author Shrey Grover, a cognitive neuroscientist in Reinhart's lab, said the extent to which the benefits of brain stimulation can be generalized to other memory tasks and whether memory improvement can last longer than a month are two key questions
the team plans to address in future studies.

He added that the research team is also expanding on whether tACS can help people like Alzheimer's, as this study suggests that brain stimulation may be most
helpful to people with poor cognitive function at first.

"We hope we can expand this work in meaningful ways and contribute more information
about how the brain works.
"
”

References:

1.
Grover, S.
, Wen, W.
, Viswanathan, V.
, Gill, C.
T.
& Reinhart, R.
M.
G.
Nature Neurosci.
https://doi.
org/10.
1038/s41593-022-01132-3 (2022).

The original article was published in the news section of Nature on August 22, 2022, using Brain stimulation leads to long-lasting improvements in memory

© nature

doi: 10.
1038/d41586-022-02298-3

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