Understanding event-related potentials (ERPs) in clinical and basic language and communication disorders research: a tutorial

Abstract

Background: Event-related potentials (ERPs), which are electrophysiological neural responses time-locked to a stimulus, have become an increasingly common tool in language and communication disorders research. They can provide complementary evidence to behavioural measures as well as unique perspectives on communication disorders. ERPs have the distinct advantage of providing precise information about the timing of neural processes and can be used in cases where it is difficult to obtain responses from participants, such as infants or individuals who are minimally verbal. However, clinicians and clinician-scientists rarely receive training in how to interpret ERP research.

Aims: To provide information that allows readers to better understand, interpret and evaluate research using ERPs. We focus on research related to communication sciences and disorders and the information that is most relevant to interpreting research articles.

Method: We explain what ERPs are and how ERP data are collected, referencing key texts and primary research articles. Potential threats to validity, guidelines for interpreting data, and the pros and cons using of ERPs are discussed. Research in the area of paediatric language disorders is used as a model; common paradigms such as the semantic incongruity N400 and auditory mismatch negativity are used as tangible examples. With this foundation of understanding ERPs, the state of the field in terms of how ERPs are used and the ways they may inform the field are discussed.

Main contribution: To date, no review has focused on ERPs as they relate to clinical or communication research. The main contribution of this review is that it provides practical information geared toward understanding ERP research.

Conclusions: ERPs offer insights into neural processes supporting communication and can both complement behaviour and provide information that behavioural measures cannot. We encourage readers to evaluate articles using ERPs critically, effectively pushing the field forward through increased understanding and rigor. What this paper adds ERPs have become more prevalent in research relevant to communication sciences and disorders. In order for clinicians to review and evaluate this research, an understanding of ERPs is needed. This review adds to the field by providing an accessible description of what ERPs are, a description of what ERP components are, and the most relevant commonly used components, as well as how ERP data are recorded and processed. With this foundational understanding of how ERPs work, guidelines for the interpretation of ERP data are given. Though few ERP studies currently have direct implications for clinical practice, we discuss several ways through which ERPs can impact clinical practice in future, by providing information that cannot be obtained by behaviour alone about the aetiology of disorders, and as potential biomarkers of disorder or treatment response.

Keywords: N400; event-related potential (ERP); mismatch negativity; neuroscience.

Figure 1.. Typical plots present in ERP research.

A) Group grand average waveforms (averaged from about 100 child participants) showing 2 conditions (frequent and rare syllables, in black and red) and the difference or subtraction between them (in blue). B) Group grand average scalp plot showing spatial distribution of the mean amplitude of the difference wave depicted in (A) within a time window of interest from 300–500ms. The negativity shown in blue extends bilaterally across fronto-central electrode sites. (Unpublished data from Author’s Lab.)

Figure 2.. How different underlying component structures can manifest as identical waveforms.

A) A theoretical ERP waveform with 3 peaks. B) One possibility for the underlying component structure that when summed together, creates the waveform in panel A. C) Another possibility for the component structure of the waveform in panel A. Notice the shorter duration of X₂ as compared to X’₂ and the larger amplitude of X₃ as compared to X’₃ in panel B.