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 simultaneously store different information, potentially helping people stay focused while multitasking.
Source: University of Rochester
New research shows that rhythmic brain activity is essential for temporarily retaining important information in memory.
Researchers from the Del Monte Institute for Neuroscience at the University of Rochester published these findings today in Current biology who found brain rhythms – or patterns of neural activity – organize the bursts of activity in the brain that maintain short-term connections.
“The idea was that the temporary storage of important information is tied to neurons in the brain that fire, retaining that information until it is no longer needed.
“Recent research has shown that it may 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 the neurons that represent the information.
“Our research shows that brain rhythms organize these transient bursts over time,” said Ian Fiebelkorn, PhD, assistant professor of neuroscience and lead author of the study.
“The rhythmic coordination of brain activity over time is important because it allows overlapping populations of neurons to store different information at the same time.”
Fiebelkorn’s previous research into how the brain processes external information, such as when navigating Times Square in New York, made a similar discovery. He and his fellow researchers found that brain rhythms help coordinate different functions associated with sampling currently important information or switching to another source of information. In this context, brain rhythms help balance focus on the task at hand and preparation for the unexpected.
In this new research, the researchers focused on sampling internally represented (or memorized) information. Using EEG, participants looked at images with vertical or horizontal lines and were asked to remember both the direction of the line and the location of the image.
The researchers found that the strength of the internal representations of these different images alternated over time, on a sub-second time scale, with rhythmic fluctuations in brain activity. Such coordination of brain activity over time allows the roles of certain neurons to overlap without conflict.
“These rhythmic brain processes could also explain how we can stay focused while multitasking, such as when trying to remember an address while driving a car,” Fiebelkorn said.
“Rather than focusing on these tasks simultaneously, we could alternate between them on a sub-second time scale.”
How the multitasking brain is the next step for the Fiebelkorn lab. “What happens when the brain has to pull external and internal samples at the same time, will we see the same kind of rhythmic temporal coordination? This is what we strive to understand next. The more we are able to learn about how these processes generally work, which helps us understand how these things go wrong in neurological disorders.
Other authors include Miral Abdalaziz and Zach Redding, PhD, of 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 Haydouk
Source: University of Rochester
Contact: Kelsie Smith Hayduk – University of Rochester
Picture: Image is in public domain
Original research: Free access.
“Rhythmic Temporal Coordination of Neural Activity Prevents Representation Conflicts During Working Memory” by Ian Fiebelkorn et al. Current biology
Abstract
Rhythmic temporal coordination of neural activity prevents representation conflicts during working memory
Strong points
- Working memory performance is linked to frequency-specific neural activity
- Different things to remember are associated with different beta phases (25 Hz)
- Theta phase appears to coordinate the activity of the behaviorally relevant beta band
- Rhythmic temporal coordination helps prevent representation conflicts
Summary
Selective attention is characterized by alternating states associated with attentional sampling or attentional shifting, helping to prevent functional conflict by isolating function-specific neural activity over time.
We hypothesized that such rhythmic temporal coordination might also help prevent representational conflicts during working memory.
Multiple items can be held simultaneously in working memory, and these items can be represented by overlapping neuronal populations.
Traditional theories propose that short-term storage of items to remember occurs through persistent neural activity, but when neurons simultaneously represent multiple items, the persistent activity creates the potential for representational conflicts.
By comparison, more recent, “silent activity” theories of working memory propose that synaptic changes also contribute to the short-term storage of items to be remembered.
Transient bursts of neuronal activity, rather than persistent activity, might serve to occasionally refresh these synaptic changes.
Here, we used EEG and response times to test whether rhythmic temporal coordination helps isolate neural activity associated with different recall 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 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 beta phase.
The present results (1) are consistent with the fact that rhythmic temporal coordination is a general mechanism for preventing functional or representational conflicts during cognitive processes and (2) inform models describing the role of oscillatory dynamics in the organization of working memory.