EEG microstates: Functional significance and short-term test-retest reliability

Area of Science:

• Neuroscience
• Cognitive Science
• Psychophysiology

Background:

• Electroencephalography (EEG) microstates represent discrete topographical patterns of brain activity.
• Understanding the functional significance and test-retest reliability of these microstates is crucial for their clinical application.
• Canonical EEG microstate classes (A, B, C, D) and their transitions are of interest.

Purpose of the Study:

• To investigate the functional significance of canonical EEG microstate classes and their pairwise transitions.
• To establish the within-session test-retest reliability of EEG microstates.
• To explore associations between microstate parameters and specific mental states (mind-wandering, verbalization, visualization).

Main Methods:

• Recorded 36-channel EEGs in 20 healthy volunteers under three eyes-closed conditions.
• Analyzed EEG data (2-20 Hz bandpass) into four canonical microstate classes (A, B, C, D).
• Assessed microstate parameters (duration, coverage) and transitions, along with subjective alertness and effort ratings.

Main Results:

• EEG microstate classes C and D were consistently dominant across all conditions.
• Average microstate duration, particularly for class D, showed the highest test-retest reliability.
• Class D duration and coverage were higher during mind-wandering compared to verbalization or visualization.
• Transitions between classes C and D were more frequent than expected, but transition probabilities lacked condition-specific differences and showed lower reliability.

Conclusions:

• EEG microstate duration is a reliable parameter, but functional significance and transitions require further research.
• Current findings suggest limited direct association between canonical microstates and specific mental states.
• Future studies should explore complex microstate syntax beyond pairwise transitions for deeper functional insights.
• Optimized experimental designs with shorter runs and breaks are recommended for improved microstate parameter reliability in clinical biomarker applications.