The MMN, or mismatch-negativity, is an
ERP component related to the processing of unexpected stimuli, particularly sounds. It is most commonly elicited by the presentation of a tone of different frequency or loudness than those tones surrounding it. The MMN is hypothesized to reflect a deviation from the expected tone, or
stimulus.
The importance of the MMN to
commonfolk is that it is used as a method to determine whether a coma victim will come out of the coma. If no MMN is elicited by a deviant tone, then the probability of coming out of the coma is low. When the MMN is present, rehabilitation during the coma is appropriate, as the victim's state is likely to improve. The MMN demonstrates that basic cognitive processing is
intact.