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Complex relationship between BOLD signal and synchronization/desynchronization of human brain MEG oscillations
Georg Winterer1, Frederick W Carver, Francesco Musso
1MEG Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, USA. georg.winterer@uni-duesseldorf.de
Human Brain Mapping
|November 30, 2006
Summary
Functional magnetic resonance imaging (fMRI) relies on brain activity coupling. This study shows that both brain synchronization and desynchronization correlate with the Blood-Oxygen-Level-Dependent (BOLD) signal, revealing a complex relationship.
Area of Science:
- Neuroimaging
- Cognitive Neuroscience
- Electrophysiology
Background:
- Functional magnetic resonance imaging (fMRI) measures brain activity via the Blood-Oxygen-Level-Dependent (BOLD) signal.
- The precise relationship between BOLD signals and underlying neural electromagnetic activity, particularly desynchronization, remains unclear.
- Previous research suggests a positive correlation between BOLD responses and cortical synchronization.
Purpose of the Study:
- To investigate the relationship between cortical desynchronization and the BOLD signal.
- To explore the complex interplay between electromagnetic activity and hemodynamic responses during cognitive tasks.
Main Methods:
- Combined event-related fMRI and 275-sensor whole-head magnetoencephalography (MEG).
- Identical visual two-choice reaction time task administered to 10 human subjects.
- Analysis of synchronized and desynchronized electromagnetic activity across various frequencies.
Main Results:
- Complex patterns of MEG synchronization and desynchronization were observed.
- These electromagnetic patterns corresponded spatially with positive BOLD responses in visual and motor areas.
- Evidence suggests BOLD signal correspondence with both synchronization and desynchronization.
Conclusions:
- The relationship between BOLD signals and electromagnetic activity is more intricate than previously assumed.
- Cortical desynchronization, not just synchronization, can be associated with positive BOLD responses.
- This finding has implications for interpreting neuroimaging data in cognitive neuroscience research.
