Effect of EEG Referencing Methods on Auditory Mismatch Negativity

Yatin Mahajan,Varghese Peter,Mridula Sharma

doi:10.3389/fnins.2017.00560

Abstract

Auditory event-related potentials (ERPs) have consistently been used in the investigation of auditory and cognitive processing in the research and clinical laboratories. There is currently no consensus on the choice of appropriate reference for auditory ERPs. The most commonly used references in auditory ERP research are the mathematically linked-mastoids (LM) and average referencing (AVG). Since LM and AVG referencing procedures do not solve the issue of electrically-neutral reference, Reference Electrode Standardization Technique (REST) was developed to create a neutral reference for EEG recordings. The aim of the current research is to compare the influence of the reference on amplitude and latency of auditory mismatch negativity (MMN) as a function of magnitude of frequency deviance across three commonly used electrode montages (16, 32, and 64-channel) using REST, LM, and AVG reference procedures. The current study was designed to determine if the three reference methods capture the variation in amplitude and latency of MMN with the deviance magnitude. We recorded MMN from 12 normal hearing young adults in an auditory oddball paradigm with 1,000 Hz pure tone as standard and 1,030, 1,100, and 1,200 Hz as small, medium and large frequency deviants, respectively. The EEG data recorded to these sounds was re-referenced using REST, LM, and AVG methods across 16-, 32-, and 64-channel EEG electrode montages. Results revealed that while the latency of MMN decreased with increment in frequency of deviant sounds, no effect of frequency deviance was present for amplitude of MMN. There was no effect of referencing procedure on the experimental effect tested. The amplitude of MMN was largest when the ERP was computed using LM referencing and the REST referencing produced the largest amplitude of MMN for 64-channel montage. There was no effect of electrode-montage on AVG referencing induced ERPs. Contrary to our predictions, the results suggest that the auditory MMN elicited as a function of increments in frequency deviance does not depend on the choice of referencing procedure. The results also suggest that auditory ERPs generated using REST referencing is contingent on the electrode arrays more than the AVG referencing.

Highlights

Event-related potentials (ERPs) are readily used to assess the brain function in response to sensory events
We compared the effects of LM, average referencing (AVG), and Reference Electrode Standardization Technique (REST) referencing procedure on the mismatch negativity (MMN) as a function of increase in deviance magnitude and 64, 32, and 16-channel scalpelectrode montages
The results revealed that the referencing procedure did not alter the MMN amplitude and latency as a function of frequency deviance across the three montages

Summary

Introduction

Event-related potentials (ERPs) are readily used to assess the brain function in response to sensory events. Auditory ERPs are used to validate and document changes in auditory processing ability after intervention, and to assess auditory plasticity of the brain after hearing rehabilitation (Sharma et al, 2002, 2005, 2014; McArthur et al, 2009). There has been no common consensus yet on the choice of appropriate referencing procedure in the ERP research laboratories across the world (Kayser and Tenke, 2010; Luck, 2014; Chella et al, 2016). Selecting an appropriate reference for EEG recording becomes a crucial process as the choice of reference can induce changes in the EEG recording and subsequently the ERP analyses i.e., latency, magnitude, and spatial changes in the ERPs (Kayser and Tenke, 2010; Tian and Yao, 2013). For a more detailed technical description of referencing procedure, see Luck (2014)

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