Phase synchronization between theta and upper alpha oscillations in a working memory task

Area of Science:

• Cognitive Neuroscience
• Neurophysiology

Background:

• Theta and upper alpha brain oscillations show selective responses to varying memory demands.
• Phase synchronization between neural oscillations is increasingly recognized for its role in cognitive functions.

Purpose of the Study:

• To investigate the role of phase synchronization between theta and upper alpha oscillations during a memory scanning task.
• To determine how phase synchronization patterns differ between memory retention and retrieval phases.

Main Methods:

• Utilized electroencephalography (EEG) to record brain activity during a memory scanning task.
• Analyzed power changes and phase synchronization between theta (3-8 Hz) and upper alpha (10-15 Hz) oscillations at various electrode sites.
• Investigated load-dependent changes in oscillatory activity and synchronization during retention and retrieval.

Main Results:

• During retention, increased upper alpha power was observed at posterior sites (O2, P4), alongside significant upper alpha:theta phase synchronization between posterior, central, and anterior sites.
• During retrieval, enhanced upper alpha phase locking occurred at O2, with increased upper alpha:theta phase synchronization between posterior and anterior sites.
• Both retention and retrieval phases exhibited load-dependent changes in upper alpha and upper alpha:theta phase synchronization.

Conclusions:

• Theta oscillations may be associated with central executive functions, while upper alpha oscillations are implicated in reactivating long-term memory codes for short-term use.
• Phase synchronization between theta and upper alpha frequencies likely reflects the dynamic interplay between these distinct memory processes.