Summary: Rhythmic brain activity plays a key role in temporarily storing important information in memory. By coordinating bursts of activity over time, overlapping populations of neurons can store different pieces of information simultaneously, potentially helping people stay focused while multitasking.
Source: University of Rochester
New research shows that rhythmic brain activity is key to temporarily maintaining important information in memory.
Researchers at the Del Monte Institute for Neuroscience at the University of Rochester published these findings today in Current Biology that found brain rhythms—or patterns of neuronal activity—organize the bursts of activity in the brain that maintain short-term connections.
“The thought has been that the temporary storage of important information is linked to neurons in the brain that just fire away, retaining that information until it is no longer needed.
“Recent research has shown that it might not be such persistent brain activity that matters most for the temporary storage of information, but rather a short-term strengthening of the connections between neurons that are representing the information.
“Our research shows that brain rhythms are organizing these transient bursts over time,” said Ian Fiebelkorn, PhD, assistant professor of Neuroscience and senior author of the study.
“The rhythmic coordination of brain activity over time is important because it allows overlapping populations of neurons to store different pieces of information at the same time.”
Fiebelkorn’s previous research around how the brain processes external information—like when navigating Times Square in New York City—made a similar discovery. He and fellow researchers found that brain rhythms help to coordinate different functions associated with either sampling presently important information or shifting to another source of information. In this context, brain rhythms help to balance focus on the task at hand with being prepared for the unexpected.
In this new research, researchers focused on sampling internally represented (or remembered) information. Using EEG, participants looked at images with vertical or horizontal lines and were asked to remember both the line direction and the location of the image.
Researchers found that the strength of the internal representations of these different images alternated over time, on a sub-second timescale, with rhythmic fluctuations in brain activity. Such coordination of brain activity over time allows the role of some neurons to overlap without conflict.
“These rhythmic brain processes might also explain how we can stay focused while multitasking—like when trying to remember an address while driving a car,” Fiebelkorn said.
“Rather than simultaneously focusing on these tasks, we might be alternating between them on a sub-second timescale.”
How the brain multitasks is the next step for the Fiebelkorn lab. “What happens when the brain has to do external and internal sampling at the same time, will we see the same sort of rhythmic temporal coordination? That is what we are working to understand next. The more we are able to learn about how these processes typically work helps us understand how these things go awry in neurological disorders.”
Additional authors include Miral Abdalaziz and Zach Redding, PhD, from the Del Monte Institute for Neuroscience at the University of Rochester.
Funding: This research was supported by the National Science Foundation and the Searle Scholars Program.
About this memory research news
Author: Kelsie Smith Hayduk
Source: University of Rochester
Contact: Kelsie Smith Hayduk – University of Rochester
Image: The image is in the public domain
Original Research: Open access.
“Rhythmic temporal coordination of neural activity prevents representational conflict during working memory” by Ian Fiebelkorn et al. Current Biology
Abstract
Rhythmic temporal coordination of neural activity prevents representational conflict during working memory
Highlights
- Working memory performance is linked to frequency-specific neural activity
- Different to-be-remembered items are associated with different beta (25 Hz) phases
- Theta phase seems to coordinate behaviorally relevant beta-band activity
- Rhythmic temporal coordination helps to prevent representational conflicts
Summary
Selective attention is characterized by alternating states associated with either attentional sampling or attentional shifting, helping to prevent functional conflicts by isolating function-specific neural activity in time.
We hypothesized that such rhythmic temporal coordination might also help to prevent representational conflicts during working memory.
Multiple items can be simultaneously held in working memory, and these items can be represented by overlapping neural populations.
Traditional theories propose that the short-term storage of to-be-remembered items occurs through persistent neural activity, but when neurons are simultaneously representing multiple items, persistent activity creates a potential for representational conflicts.
In comparison, more recent, “activity-silent” theories of working memory propose that synaptic changes also contribute to short-term storage of to-be-remembered items.
Transient bursts in neural activity, rather than persistent activity, could serve to occasionally refresh these synaptic changes.
Here, we used EEG and response times to test whether rhythmic temporal coordination helps to isolate neural activity associated with different to-be-remembered items, thereby helping to prevent representational conflicts.
Consistent with this hypothesis, we report that the relative strength of different item representations alternates over time as a function of the frequency-specific phase.
Although RTs were linked to theta (∼6 Hz) and beta (∼25 Hz) phases during a memory delay, the relative strength of item representations only alternated as a function of the beta phase.
The present findings (1) are consistent with rhythmic temporal coordination being a general mechanism for preventing functional or representational conflicts during cognitive processes and (2) inform models describing the role of oscillatory dynamics in organizing working memory.
