Electrocorticographic Activation Patterns of Electroencephalographic Microstates.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Brain Imaging

Background:

• Electroencephalography (EEG) microstates are brief, stable periods of scalp electrical activity reflecting brain network states.
• These microstates are hypothesized to mediate local brain activity patterns.
• Understanding the relationship between global EEG microstates and local neural activity is crucial for deciphering brain function.

Purpose of the Study:

• To investigate the correlation between global EEG microstate dynamics and local electrocorticography (ECoG) and stereotactic EEG (SEEG) recordings.
• To determine if specific frequency bands, particularly gamma, are involved in this relationship.
• To validate findings against previous neuroimaging studies.

Main Methods:

• Simultaneous noninvasive scalp EEG and invasive ECoG/SEEG recordings from two epilepsy patients were analyzed.
• Normative EEG microstate template maps were fitted to scalp EEG data.
• Covariance mapping was used to correlate EEG microstate timelines with ECoG/SEEG temporo-spectral evolutions across different frequency bands (theta, alpha, beta, high-gamma).

Main Results:

• Significant covariation was found between ECoG/SEEG spectral amplitudes and EEG microstate timelines across all analyzed frequency bands (p < 0.001).
• Covariance patterns were consistent across electrodes and participants.
• This study provides the first evidence of distinct local field potential patterns in ECoG/SEEG associated with simultaneous EEG microstates.

Conclusions:

• Global EEG microstate dynamics are systematically related to local neural activity patterns measured by ECoG and SEEG.
• These relationships manifest across multiple frequency bands, suggesting a broad involvement of neural oscillations.
• The findings support the role of EEG microstates as indicators of underlying local brain network states.