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Concurrent EEG and Functional MRI Recording and Integration Analysis for Dynamic Cortical Activity Imaging
Published on: June 30, 2018
Simultaneous EEG-fMRI during a working memory task: modulations in low and high frequency bands.
Lars Michels1, Kerstin Bucher, Rafael Lüchinger
1Functional Neurosurgery, University Hospital Zürich, Zürich, Switzerland. lars.michels@kispi.uzh.ch
Plos One
|April 28, 2010
Summary
This study reveals that brain oscillations across various frequencies (theta, alpha, beta, gamma) correlate differently with blood-oxygen-level-dependent (BOLD) signals in specific brain regions during working memory (WM) tasks. These findings link both low and high frequency brain activity to neurovascular processes.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Neuroimaging
Background:
- Working memory (WM) involves load-dependent frequency band modulations observed in EEG studies.
- fMRI studies link WM load to activity in the dorsolateral prefrontal cortex (DLPFC), medial prefrontal cortex (MPFC), and posterior parietal cortex (PPC).
- Previous research indicated negative correlations between low-frequency EEG bands (theta, alpha) and BOLD signals during WM retention.
Purpose of the Study:
- To investigate the coupling between higher EEG frequency bands (beta, gamma) and BOLD signals during WM.
- To determine if load-sensitive brain regions exhibit distinct frequency band-BOLD signal correlations.
- To explore the relationship between EEG frequency bands and BOLD signals across different WM loads.
Main Methods:
- EEG-fMRI correlations were examined for theta, alpha, beta, and gamma bands during WM retention in 16 healthy adults.
- Participants performed a WM task with set sizes of 2 and 5.
- Load-sensitive brain regions were analyzed for frequency band-specific BOLD signal effects.
Main Results:
- Negative theta-BOLD correlations were found in MPFC, PPC, and cingulate cortex.
- Alpha1 showed mixed positive (ACC, MPFC, PCC) and negative (DLPFC, PPC, IFG) correlations; alpha2 showed negative correlations in parieto-occipital regions.
- Beta and gamma bands predominantly showed positive BOLD correlations, particularly in DLPFC and MPFC, with load analysis revealing positive effects for theta, beta, and gamma, and negative effects for alpha1.
Conclusions:
- EEG-BOLD signal correlation directions vary significantly across brain regions and EEG frequency bands.
- Certain brain regions exhibit both load-sensitive BOLD and frequency band effects.
- Both lower and higher frequency brain oscillations are demonstrably linked to neurovascular processes underlying working memory.
