You might remember you ate cereal for breakfast but forget the color of the bowl. Or recall watching your partner put the milk away but can’t remember on which shelf.
A new Northwestern Medicine
study improved memory of complex, realistic events similar to these by applying
transcranial magnetic stimulation (TMS) to the brain network responsible for
memory. The authors then had participants watch videos of realistic activities
to measure how memory works during everyday tasks. The findings prove it is
possible to measure and manipulate realistic types of memory.
“On a day-to-day basis we
must remember complex events that involve many elements, such as different
locations, people and objects,” said lead author Melissa Hebscher, a
postdoctoral fellow at Northwestern University Feinberg School of Medicine. “We
were able to show that memory for complex, realistic events can be improved in
a safe and non-invasive way using brain stimulation.”
The study was conducted on
healthy young adults in a controlled laboratory setting. These methods,
however, also could eventually be used to improve memory in individuals with
memory disorders due to brain damage or neurological disorders, Hebscher said.
A
new approach to studying memory: Incorporating video
The study authors used TMS
with the goal of altering brain activity and memory for realistic events.
Immediately following stimulation, subjects performed a memory task while
having their brains scanned using functional magnetic resonance imaging (fMRI).
Instead of showing study
participants pictures or lists of words — typical practices in laboratory tests
that analyze memory — participants in this study watched videos of everyday
activities such as such as someone folding laundry or taking out the garbage.
“Our study used video clips
that more closely replicate how memory works on a day-to-day basis,” Hebscher
said.
Following stimulation, study
participants more accurately answered questions about the content of the video
clips, such as identifying the shirt color an actor was wearing or the presence
of a tree in the background.
Additionally, the study found
that brain stimulation led to higher quality reinstatement of memories in the
brain. Reinstatement is when the brain replays or relives an original event,
Hebscher said. Following stimulation, a person’s brain activity while watching
a video more closely resembled their brain activity when remembering that same
video.
“This is why remembering can
sometimes feel like ‘mental time travel,'” Hebscher said. “Our findings show
that stimulation enhances this ‘mental time travel’ in the brain and improves
memory accuracy. These findings have implications for the development of safe
and effective ways to improve real-world memory.”
How
the study worked
The study authors used a
brain imaging technique called multi-voxel pattern analysis to compare patterns
of brain activity when subjects were watching a video to brain activity when
subjects were remembering that same video. The scientists measured the effect
of stimulation by comparing memory and brain activity following stimulation of the
memory network to the same measures following stimulation of a control brain
region that does not belong to the memory network.
During the memory test,
subjects watched a large set of video clips and later remembered them and
answered true/false questions about the content of the videos. The researchers
found that memory network stimulation improved the number of questions that
subjects answered correctly. It also increased reinstatement of videos in brain
regions associated with visual processing.
“Follow-up studies will work
to gather more reliable measures of the brain network responsible for memory in
healthy subjects as well as in patients with memory disorders,” Hebscher said.
“Having a more reliable measurement of this network will help us more easily
identify reinstatement in the brain and may help improve the effectiveness of
stimulation for enhancing memory.”
Source: https://news.northwestern.edu/stories/2021/02/brain-stimulation-boosts-memory-replay-accuracy/
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