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Updated: Mar 2, 2026
Recording Brain Activity with Ear-Electroencephalography
Published on: March 31, 2023
A Comparative Study of Average, Linked Mastoid, and REST References for ERP Components Acquired during fMRI
Ping Yang1, Chenggui Fan1, Min Wang1
1Key Laboratory for NeuroInformation of Ministry of Education, High-Field Magnetic Resonance Brain Imaging Key Laboratory of Sichuan Province, Center for Information in Medicine, School of Life Science and Technology, University of Electronic Science and Technology of ChinaChengdu, China.
The Reference Electrode Standardization Technique (REST) offers superior electroencephalogram (EEG) analysis in simultaneous EEG-fMRI studies compared to average reference (AR) and linked mastoid (LM) methods. REST provides more accurate event-related potential (ERP) results, crucial for understanding brain activity.
Area of Science:
- Neuroscience
- Cognitive Science
- Biomedical Engineering
Background:
- Simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) are powerful tools for studying brain activity.
- Re-referencing techniques like average reference (AR) and linked mastoid (LM) are commonly used in event-related potential (ERP) analysis but can introduce artifacts.
- A reference electrode standardization technique (REST) was developed to overcome these limitations by calculating a reference point at infinity.
Purpose of the Study:
- To compare the effectiveness of AR, LM, and REST re-referencing methods in simultaneous EEG-fMRI studies.
- To evaluate the impact of different references on task-related ERP components during a working memory task.
- To determine the optimal reference method for accurate ERP analysis in combined EEG-fMRI research.
Main Methods:
- Simultaneous EEG-fMRI recording during a visual working memory task.
- Application of AR, LM, and REST re-referencing techniques to the EEG data.
- Analysis of task-related ERP components (N1 and P300) and their topographical distributions.
- Cortical source estimation of ERPs as a reference-independent measure.
- Comparison with fMRI activation data and EEG-only study results.
Main Results:
- While references did not alter ERP component topography, they significantly impacted task-related effects.
- LM reference reduced or eliminated the visual working memory load effect on P300.
- AR reference distorted the spatial distribution of working memory location effects on N1.
- REST reference yielded more integrated and reliable ERP results, corroborated by fMRI and EEG-only findings.
Conclusions:
- REST is recommended as the optimal reference method for ERP analysis in simultaneous EEG-fMRI studies.
- The choice of reference significantly influences the interpretation of task-related ERP effects.
- REST, particularly with a realistic head model, enhances the accuracy and validity of combined EEG-fMRI research.
