Noncanonical EEG-BOLD coupling by default and in schizophrenia

Area of Science:

• Neuroscience
• Neuroimaging
• Psychiatry

Background:

• Current neuroimaging relies on models of neurovascular coupling where hemodynamic responses follow neural activity by seconds.
• Emerging evidence shows noncanonical blood oxygen level dependent (BOLD) responses that are delayed under stress and aberrant in neuropsychiatric conditions.

Purpose of the Study:

• To investigate the coupling between BOLD signals and resting-state neural activity fluctuations.
• To examine time-lagged BOLD correlations with alpha band power in individuals with schizophrenia and healthy controls.

Main Methods:

• Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) recordings.
• Voxelwise, time-lagged correlation analysis of alpha band power and BOLD signals.
• Focus on the default mode network (DMN) and other brain regions.

Main Results:

• Observed diverse temporal profiles of alpha-BOLD coupling within the DMN.
• Found early coupling (0-2s lag) in posterior DMN regions, thalamus, and brainstem.
• Anterior DMN regions exhibited canonical lags (4-6s), with longer lags associated with stress and schizophrenia.

Conclusions:

• Noncanonical alpha-BOLD coupling is widespread and delayed in individuals with schizophrenia.
• Findings support the hemo-neural hypothesis, suggesting blood flow/metabolism can regulate neural activity.
• The hemo-neural lag may be linked to subjective arousal or stress, highlighting the need for studies in psychiatric conditions.