Related Experiment Videos
Long-range EEG phase synchronization during an arithmetic task indexes a coherent cortical network simultaneously
Hiroaki Mizuhara1, Li-Qun Wang, Koichiro Kobayashi
1Laboratory for Dynamics of Emergent Intelligence, RIKEN Brain Science Institute, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan. hmizu@brain.riken.jp
Neuroimage
|June 1, 2005
Summary
Brain region synchronization, measured by electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), integrates distant brain activities during cognitive tasks. Beta-band synchronization links brain regions involved in working memory.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Brain Imaging
Background:
- The integration of distributed brain activities for cognitive processing remains an open question.
- Long-range phase synchronization, observable via scalp electroencephalography (EEG), is a potential neural mechanism for functional integration.
- Synchronization can occur at neuronal firing or local field potential levels, detectable in EEG under specific conditions.
Purpose of the Study:
- To investigate the role of phase synchronization in integrating distant brain regions.
- To develop a method combining simultaneous functional magnetic resonance imaging (fMRI) and EEG to extract task-dependent phase synchronization.
- To analyze the relationship between phase synchronization and brain activity during a cognitive task.
Main Methods:
- Simultaneous fMRI and EEG acquisition during a mental arithmetic task.
- Development of a method to extract task-dependent phase synchronization from combined fMRI-EEG data.
- Functional connectivity analysis of brain regions exhibiting significant phase synchronization.
Main Results:
- A significant task-dependent increase in beta-band (around 14 Hz) phase synchronization was observed across bilateral parietal sites.
- This beta synchronization correlated with both positive and negative Blood-Oxygen-Level-Dependent (BOLD) responses.
- Functional connectivity analysis revealed that increased hemispheric beta synchronization linked cross-hemispheric and anterior-posterior brain regions, including the prefrontal cortex, putamen, and temporal gyrus.
Conclusions:
- Phase synchronization, particularly in the beta band, plays a crucial role in integrating distributed neural activities across distant brain regions.
- The findings suggest a network involving both positive and negative BOLD regions, linked by beta synchronization.
- Beta synchronization may be important for the formation and function of working memory networks.