Combining EEG and fMRI: a multimodal tool for epilepsy research

Area of Science:

• Neuroscience
• Medical Imaging
• Epileptology

Background:

• Epilepsy diagnosis often relies on electroencephalogram (EEG) identifying abnormal neuronal discharges (spikes).
• Locating the precise brain generators of these epileptic spikes and associated involved regions is challenging.
• Subtle EEG abnormalities may lack overt clinical manifestations, complicating diagnosis and localization.

Purpose of the Study:

• To review the methodology of combining EEG and functional MRI (fMRI) for epilepsy research.
• To explore how fMRI can identify brain regions activated or deactivated by epileptic spikes.
• To discuss the interpretation of blood oxygen level dependent (BOLD) signal changes in response to epileptic activity.

Main Methods:

• Simultaneous EEG recording within an MRI scanner.
• fMRI data acquisition during EEG monitoring.
• Statistical analysis of combined EEG and fMRI time series data.
• Review of existing studies on EEG-fMRI in various epilepsy types.

Main Results:

• Successful integration of EEG and fMRI allows visualization of brain responses to epileptic spikes.
• Identified brain regions show BOLD signal changes (both increases and decreases) correlated with epileptic discharges.
• Results vary depending on epilepsy type and spike characteristics.

Conclusions:

• EEG-fMRI is a valuable tool for investigating the neural networks underlying epileptic seizures.
• Understanding BOLD signal changes provides insights into the pathophysiology of epilepsy.
• Further research is needed to refine interpretation of complex EEG-fMRI findings in epilepsy.