Electric current to brain boosts memory: May help treat memory
disorders from stroke, Alzheimer’s, brain injury
August 28, 2014
Stimulating a region in the brain via non-invasive delivery of
electrical current using magnetic pulses, called Transcranial
Magnetic Stimulation, improves memory. The discovery opens a new
field of possibilities for treating memory impairments caused by
conditions such as stroke, early-stage Alzheimer’s disease,
traumatic brain injury, cardiac arrest and the memory problems that
occur in healthy aging.
New research indicates that stimulating a particular region in the
brain via non-invasive delivery of electrical current using
magnetic pulses, called Transcranial Magnetic Stimulation, improves
Credit: Image from video courtesy of Northwestern University
[Click to enlarge image]
Stimulating a particular region in the brain via non-invasive
delivery of electrical current using magnetic pulses, called
Transcranial Magnetic Stimulation, improves memory, reports a new
Northwestern Medicine® study.
The discovery opens a new field of possibilities for treating
memory impairments caused by conditions such as stroke, early-stage
Alzheimer’s disease, traumatic brain injury, cardiac arrest and the
memory problems that occur in healthy aging.
“We show for the first time that you can specifically change memory
functions of the brain in adults without surgery or drugs, which
have not proven effective,” said senior author Joel Voss, assistant
professor of medical social sciences at Northwestern University
Feinberg School of Medicine. “This noninvasive stimulation improves
the ability to learn new things. It has tremendous potential for
treating memory disorders.”
The study will be published August 29 in Science.
The study also is the first to demonstrate that remembering events
requires a collection of many brain regions to work in concert with
a key memory structure called the hippocampus — similar to a
symphony orchestra. The electrical stimulation is like giving the
brain regions a more talented conductor so they play in closer
“It’s like we replaced their normal conductor with Muti,” Voss
said, referring to Riccardo Muti, the music director of the
renowned Chicago Symphony Orchestra. “The brain regions played
together better after the stimulation.”
The approach also has potential for treating mental disorders such
as schizophrenia in which these brain regions and the hippocampus
are out of sync with each other, affecting memory and cognition.
TMS Boosts Memory
The Northwestern study is the first to show TMS improves memory
long after treatment. In the past, TMS has been used in a limited
way to temporarily change brain function to improve performance
during a test, for example, making someone push a button slightly
faster while the brain is being stimulated. The study shows that
TMS can be used to improve memory for events at least 24 hours
after the stimulation is given.
Finding the Sweet Spot
It isn’t possible to directly stimulate the hippocampus with TMS
because it’s too deep in the brain for the magnetic fields to
penetrate. So, using an MRI scan, Voss and colleagues identified a
superficial brain region a mere centimeter from the surface of the
skull with high connectivity to the hippocampus. He wanted to see
if directing the stimulation to this spot would in turn stimulate
the hippocampus. It did.
“I was astonished to see that it worked so specifically,” Voss said.
When TMS was used to stimulate this spot, regions in the brain
involved with the hippocampus became more synchronized with each
other, as indicated by data taken while subjects were inside an MRI
machine, which records the blood flow in the brain as an indirect
measure of neuronal activity.
The more those regions worked together due to the stimulation, the
better people were able to learn new information.
How the Study Worked
Scientists recruited 16 healthy adults ages 21 to 40. Each had a
detailed anatomical image taken of his or her brain as well as 10
minutes of recording brain activity while lying quietly inside an
MRI scanner. Doing this allowed the researchers to identify each
person’s network of brain structures that are involved in memory
and well connected to the hippocampus. The structures are slightly
different in each person and may vary in location by as much as a
“To properly target the stimulation, we had to identify the
structures in each person’s brain space because everyone’s brain is
different,” Voss said.
Each participant then underwent a memory test, consisting of a set
of arbitrary associations between faces and words that they were
asked to learn and remember. After establishing their baseline
ability to perform on this memory task, participants received brain
stimulation 20 minutes a day for five consecutive days.
During the week they also received additional MRI scans and tests
of their ability to remember new sets of arbitrary word and face
parings to see how their memory changed as a result of the
stimulation. Then, at least 24 hours after the final stimulation,
they were tested again.
At least one week later, the same experiment was repeated but with
a fake placebo stimulation. The order of real stimulation and
placebo portions of the study was reversed for half of the
participants, and they weren’t told which was which.
Both groups performed better on memory tests as a result of the
brain stimulation. It took three days of stimulation before they
“They remembered more face-word pairings after the stimulation than
before, which means their learning ability improved,” Voss said.
“That didn’t happen for the placebo condition or in another control
experiment with additional subjects.”
In addition, the MRI showed the stimulation caused the brain
regions to become more synchronized with each other and the
hippocampus. The greater the improvement in the synchronicity or
connectivity between specific parts of the network, the better the
performance on the memory test. “The more certain brain regions
worked together because of the stimulation, the more people were
able to learn face-word pairings, ” Voss said.
Using TMS to stimulate memory has multiple advantages, noted first
author Jane Wang, a postdoctoral fellow in Voss’s lab at Feinberg.
“No medication could be as specific as TMS for these memory
networks,” Wang said. “There are a lot of different targets and
it’s not easy to come up with any one receptor that’s involved in
“This opens up a whole new area for treatment studies where we will
try to see if we can improve function in people who really need
it,” Voss said.
His current study was with people who had normal memory, in whom he
wouldn’t expect to see a big improvement because their brains are
already working effectively.
“But for a person with brain damage or a memory disorder, those
networks are disrupted so even a small change could translate into
gains in their function,” Voss said.
In an upcoming trial, Voss will study the electrical stimulation’s
effect on people with early-stage memory loss.
Voss cautioned that years of research are needed to determine
whether this approach is safe or effective for patients with
Alzheimer’s disease or similar disorders of memory.
The above story is based on materials provided by Northwestern
University. Note: Materials may be edited for content and length.
1.J. X. Wang, L. M. Rogers, E. Z. Gross, A. J. Ryals, M. E. Dokucu,
K. L. Brandstatt, M. S. Hermiller, J. L. Voss. Targeted enhancement
of cortical-hippocampal brain networks and associative memory.
Science, 2014; 345 (6200): 1054 DOI: 10.1126/science.1252900
Cite This Page:
Northwestern University. “Electric current to brain boosts memory:
May help treat memory disorders from stroke, Alzheimer’s, brain
injury.” ScienceDaily. ScienceDaily, 28 August 2014.
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