Mismatch negativity

What is mismatch negativity (MMN)?

MMN is an auditory event-related potential that is generated when a stimulus feature deviates from the regularity of previous auditory stimuli. This deviance can be a simple physical characteristic, such as tone duration, intensity, frequency or location; or more abstract presentation characteristics, such as a lower tone in a series of ascending tones. In this way, MMN generation relies on the creation of an auditory (echoic) memory trace for the preceding tones, in order to identify the subsequent deviance. MMN is thought to be an automatic, pre-attentional process and functions as an index of auditory discrimination and echoic memory integrity. MMN is observed as the difference in ERP wave response to the standard stimuli and the deviant stimulus. Larger differences between standard and deviant stimuli and lower probability of deviant occurrence are both associated with larger MMN amplitude.

What is the evidence on MMN?

Moderate to high quality evidence finds a large MMN deficit in people with schizophrenia compared to controls, which was largest in studies of chronic patients, in studies using duration deviants rather than frequency or intensity deviants, and when tones were unattended rather than attended. Moderate to low quality evidence finds no associations between MMN deficits and symptom severity.

Moderate quality evidence finds a medium-sized deficit in duration deviants, but not in pitch deviants, in people with first-episode psychosis. There was a medium-sized MMN deficit in people at clinical high risk of schizophrenia (people with subclinical symptoms), and a small MMN deficit in people at familial high risk of schizophrenia (people with a first-degree relative with schizophrenia).

October 2020

Last updated at: 4:23 am, 29th October 2020
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