Cortical and subcortical correlates of electroencephalographic alpha rhythm modulation

Area of Science:

• Neuroscience
• Cognitive Neuroscience

Background:

• The neural basis of electroencephalographic (EEG) alpha rhythm remains unclear.
• Understanding alpha rhythm's relationship with brain activity is crucial for neuroscience.

Purpose of the Study:

• To investigate the relationship between EEG alpha rhythm and blood-oxygen-level-dependent (BOLD) signals measured by functional magnetic resonance imaging (fMRI).
• To explore the temporal dynamics and brain regions associated with alpha rhythm activity.

Main Methods:

• Simultaneous recording of topographical EEG and fMRI in awake humans.
• Independent component analysis (ICA) to isolate alpha rhythm components.
• General linear model (GLM) analysis to correlate alpha component amplitudes with fMRI BOLD signals.

Main Results:

• EEG alpha rhythm amplitude was inversely correlated with BOLD signal decreases in occipital (visual) areas.
• A significant positive correlation was found between alpha rhythm and BOLD signals in thalamic and mesencephalic regions with a short time lag.
• These findings suggest widespread thalamocortical synchronization associated with decreased brain metabolism.

Conclusions:

• The inverse relationship between alpha rhythm and BOLD signals in visual areas indicates reduced metabolic activity during alpha rhythm.
• The short time lag in thalamic and midbrain correlations suggests neural activity preceding EEG changes.
• This research provides insights into the brain's metabolic and functional organization during alpha rhythm generation.