Nav: Home

Stimulation excites the brain to form better memories

August 22, 2018

CHICAGO --- For the first time, scientists were able to specifically change the way the brain's memory centers form new memories, according to a new Northwestern Medicine study.

The study targeted a specific area of the brain using a combination of MRI brain scans and noninvasive brain stimulation, which improved the brain's ability to make new memories. The study authors used MRI to measure participants' brain activity while they played a memory game after receiving the stimulation, and found that their brain improvement lasted for at least 24 hours after receiving the stimulation.

Previous research from the same Northwestern Medicine scientists has shown it is possible to improve memory with stimulation, but this study is novel because it successfully identified how the brain changed - its level of excitability increased - in order to improve memory.

"If you think about the brain's memory network as generating one unit of activity every time it tries to memorize a picture, brain stimulation made it so that now the same type of picture would generate two units of activity," said senior study author Joel Voss, associate professor at Northwestern University Feinberg School of Medicine. "This increase in activity means that stimulation enhanced excitability, and that's important because excitability is a marker for good memory formation."

The study will be published Wednesday, Aug. 22, in the journal Science Advances.

The study's findings deepen our current understanding of how memory is organized in the brain and therefore how memory works. The implications - though still requiring substantial further development - could give hope to people suffering from memory problems, such as those due to aging or brain damage.

"Being able to manipulate the memory network in this very specific way certainly holds promise in the ability to intervene in disorders of memory, which occur for a variety of reasons," Voss said.

Voss cautioned that there are many more steps between his basic science study and an effective clinical intervention, but said his findings indicate that it's a research path worth pursuing.

"The fact that we can use noninvasive stimulation to increase excitability in this targeted brain network means we're making the network do more of what it naturally does to succeed at memory formation," Voss said.

Voss has previously used noninvasive brain stimulation - transcranial magnetic stimulation (TMS) - to improve memory, but this study helped decipher what the memory network was doing differently during the stimulation to allow it to improve its performance.

What the study found was that while the brain network was undergoing stimulation and forming a new memory, the excitability in the subject's brain network increased dramatically.

After receiving TMS for several consecutive days, study participants would play a memory game to assess how much their associative memory had improved. The "robust" effects of the stimulation were consistent across almost all study subjects, Voss said.

Although there are different kinds of memory, Voss' study focused on associative contextual memory, which is thought to be created in a specific posterior network of the hippocampus. This type of memory is an arbitrary collection of little pieces - a shirt, a face, a room, for example - that the brain binds together to create a coherent association that can be recalled later.

"That's the kind of memory that the hippocampus and this network of regions is thought to do, and that's exactly the kind of memory we tested in our experiment to determine how TMS influenced this network's ability to do that kind of memory formation," Voss said.

The study included 32 Chicago subjects (16 in the experimental group, 16 in the control group) between the ages of 18 and 35 who had normal, healthy memory and cognitive abilities. Participants underwent an MRI scan of their brain before receiving stimulation. To precisely identify where the study participant's hippocampal network was located, the scientists used a sterotactic positioning system - a navigator tool consisting of a forehead sensor, camera and a pinpoint tool - to localize the position of the physical head as it related to participant's brain scan from the MRI. This ensured Voss' lab members were administering the TMS to the correct area of the subject's brain.

Participants then received 20 minutes of repetitive TMS to the stimulation target in their brain via a magnetic stimulating coil for five consecutive days. The TMS feels like a mild tapping at 20 beats per second, Voss said.

Voss' lab members tested the memory of study participants by asking them to look at several images and try to associate them or remember their location.

"Essentially, every day in the experiment that we tested them, subjects would play the 'Memory' game, where they would have to remember that a picture went in a particular spot or they'd have to remember that two pictures went together while we used MRI to measure their brain activity," Voss said. "And what stimulation did was improve their performance to be able to play that game and improve the activity of their memory network while playing the game."
This research was supported by grant R01-MH106512 from the National Institute of Mental Health, grants T32-AG20506 and F31-AG057109 from the National Institute on Aging and grant T32-NS047987 from the National Institute of Neurological Disorders and Stroke.

Aneesha Nilakantan, Molly Hermiller, Robert Palumbo and Dr. Stephen VanHaerents of Feinberg were co-authors on the paper.

More news at Northwestern Now

Find experts on our Faculty Experts Hub

Follow @NUSources for expert perspectives

Northwestern University

Related Memory Articles:

Taking photos of experiences boosts visual memory, impairs auditory memory
A quick glance at any social media platform will tell you that people love taking photos of their experiences -- whether they're lying on the beach, touring a museum, or just waiting in line at the grocery store.
Think you know how to improve your memory? Think again
Research from Katherine Duncan at the University of Toronto suggests we may have to rethink how we improve memory.
Improving memory with magnets
The ability to remember sounds, and manipulate them in our minds, is incredibly important to our daily lives -- without it we would not be able to understand a sentence, or do simple arithmetic.
Who has the better memory -- men or women?
In the battle of the sexes, women have long claimed that they can remember things better and longer than men can.
New study of the memory through optogenetics
A collaboration between Universitat Autònoma de Barcelona and Harvard University pioneers the increase of memory using optogenetics in mice in Spain.
Peppermint tea can help improve your memory
Peppermint tea can improve long-term and working memory and in healthy adults.
A new glimpse into working memory
MIT study finds bursts of neural activity as the brain holds information in mind, overturns a long-held model.
Memory ensembles
For over forty years, neuro-scientists have been interested in the biological mechanisms underlying the storage of the information that our brain records every day.
What is your memory style?
Why is it that some people have richly detailed recollection of past experiences (episodic memory), while others tend to remember just the facts without details (semantic memory)?
Watching a memory form
Neuroscientists at Rosalind Franklin University of Medicine and Science have discovered a novel mechanism for memory formation.

Related Memory Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".