Disentangling Event-Related Potential and Oscillatory Sources using Time- and Frequency-Domain Source Imaging

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Event-related potentials (ERPs) and neural oscillations are fundamental electrophysiological measures of brain activity.
• Understanding the neural sources of these signals is crucial for deciphering cognitive processes.
• Existing source localization techniques often focus on either the time or frequency domain, potentially limiting a comprehensive understanding.

Purpose of the Study:

• To determine if ERPs and neural oscillations originate from common or distinct neural sources.
• To evaluate the combined utility of time-domain (eLORETA) and frequency-domain (DICS) EEG source localization methods.
• To investigate the relationship between ERP components and oscillatory dynamics in specific frequency bands.

Main Methods:

• Applied eLORETA (time-domain) and DICS (frequency-domain) source localization to simulated and real EEG data.
• Assessed the spatial accuracy and specificity of both methods using simulations.
• Analyzed the correspondence between ERPs (P300, N1, N400) and oscillatory activity (alpha desynchronization).

Main Results:

• eLORETA and DICS showed overlapping sources for the P300, suggesting a shared neural origin.
• Alpha desynchronization, while temporally aligned with P300, originated from distinct spatial locations.
• Auditory N1 potentials showed bilateral activation, with eLORETA providing higher spatial precision.
• N400 sources localized by DICS overlapped with eLORETA, indicating a distributed semantic network.

Conclusions:

• ERP components can arise from a mix of shared and distinct oscillatory sources, varying with frequency and cognitive function.
• The complementary application of eLORETA and DICS improves the interpretability of neural source dynamics.
• Integrating time- and frequency-domain source imaging is valuable for understanding stimulus-locked brain responses.