sLORETA allows reliable distributed source reconstruction based on subdural strip and grid recordings.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Source localization using invasive electroencephalography (EEG) is crucial for presurgical epilepsy diagnostics.
• Standardized low-resolution brain electromagnetic tomography (sLORETA) is a method for reconstructing neural activity from EEG data.

Purpose of the Study:

• To investigate factors influencing reliable source reconstruction with sLORETA using invasive subdural grid and strip electrode recordings.
• To evaluate the accuracy of sLORETA in localizing simulated and patient-specific epileptic sources.

Main Methods:

• Simulations using patient-specific MRI-derived head models and electrode positions.
• Focal dipolar sources and spatiotemporal patches served as simulated inputs.
• Analysis included localization error, activation volume, and time-course correlation, supplemented by patient spike activity localization.

Main Results:

• sLORETA achieved zero localization error for noise-free simulated data.
• Added noise reduced reliable source localizations (≤15 mm error) to 67.8%.
• Activation volume accurately represented focal generators only near electrode contacts; time courses were significantly correlated.

Conclusions:

• sLORETA is a viable distributed source model for reliable source localization with invasive grid and strip electrodes.
• Overestimation of generator extent must be considered for distant sources.
• sLORETA holds potential for enhancing the localization of distributed generators in epilepsy surgery and cognitive neuroscience.