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Variability of EEG synchronization during a working memory task in healthy subjects
Cornelis J Stam1, Anne-Marie van Cappellen van Walsum, Sifis Micheloyannis
1Department of Clinical Neurophysiology, VU University Medical Centre, Amsterdam, The Netherlands. cj.stam@vumc.nl
Summary
Working memory involves changes in brainwave synchronization and its variability. This study reveals how neural interactions fluctuate during cognitive tasks, impacting brain activity balance.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Brain Activity Analysis
Background:
- Working memory (WM) is linked to altered EEG synchronization patterns.
- Previous research noted changes in mean synchronization levels during WM tasks.
- The impact of WM on the variability of synchronization remains less understood.
Purpose of the Study:
- To investigate if changes in mean EEG synchronization during working memory are accompanied by alterations in synchronization variability.
- To explore the relationship between working memory load and the small-scale fluctuations of neural interactions.
- To determine how synchronization entropy changes across different frequency bands during a visual working memory task.
Main Methods:
- Recorded 19-channel EEGs from 21 healthy older adults at rest and during a visual working memory task.
- Computed EEG synchronization using the synchronization likelihood method across six frequency bands (2-50 Hz).
- Quantified the variability of synchronization using synchronization entropy.
Main Results:
- Working memory increased synchronization in the 2-6 Hz band and decreased it in the 6-10, 14-18, and 18-22 Hz bands.
- Synchronization variability increased in the 2-6 Hz band during working memory.
- Synchronization variability decreased in the 6-10 Hz, 14-18 Hz, and 18-22 Hz bands during working memory.
Conclusions:
- Working memory affects not only the mean level of neural network interactions but also the fluctuations within these interactions.
- Altered synchronization variability may play a role in optimizing the balance between local differentiation and global integration of brain activity.
- Dynamic changes in neural coupling, characterized by rapid fluctuations, are crucial for effective cognitive processing during working memory.