Where the BOLD signal goes when alpha EEG leaves

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Imaging

Background:

• Simultaneous EEG-fMRI studies show conflicting results on alpha band activity and brain topography during rest.
• Spontaneous fluctuations in alpha power during eyes-closed rest are a key focus in understanding brain states.

Purpose of the Study:

• To resolve discrepancies in EEG-fMRI findings related to alpha band power.
• To investigate the topographical patterns of brain activity associated with alpha power decreases.
• To explore the influence of broader EEG spectral activity on these patterns.

Main Methods:

• Re-analysis of existing simultaneous EEG-fMRI data using single-subject analyses.
• Examination of EEG spectral power (theta, alpha, beta) in relation to fMRI signal changes.
• Categorization of fMRI signal increases into 'visual' and 'attentional' patterns.

Main Results:

• Alpha power decreases correlated with distinct fMRI patterns: occipital ('visual') or frontal/parietal ('attentional').
• The 'visual' pattern showed higher relative theta power during alpha desynchronization.
• The 'attentional' pattern exhibited higher relative beta power.
• Sessions not fitting these patterns had the lowest theta and highest beta power.

Conclusions:

• The observed brain activation pattern during alpha power reduction depends on the overall brain activity level, indicated by the EEG's broader spectral range.
• Findings suggest EEG criteria could potentially stage brain activity during wakefulness, similar to sleep staging.
• This research reframes the understanding of 'resting state' and 'default mode' network activity.