The mismatch negativity (MMN) – A unique window to disturbed central auditory processing in ageing and different clinical conditions

In this article, we review clinical research using the mismatch negativity (MMN), a change-detection response of the brain elicited even in the absence of attention or behavioural task. In these studies, the MMN was usually elicited by employing occasional frequency, duration or speech-sound changes in repetitive background stimulation while the patient was reading or watching videos. It was found that in a large number of different neuropsychiatric, neurological and neurodevelopmental disorders, as well as in normal ageing, the MMN amplitude was attenuated and peak latency prolonged.Besides indexing decreased discrimination accuracy, these effects may also reflect, depending on the specific stimulus paradigm used, decreased sensory-memory duration, abnormal perception or attention control or, most importantly, cognitive decline. In fact, MMN deficiency appears to index cognitive decline irrespective of the specific symptomatologies and aetiologies of the different disorders involved.

► The mismatch negativity (MMN) indexes different types of central auditory abnormalities in different neuropsychiatric, neurological, and neurodevelopmental disorders.
► The diminished amplitude/prolonged peak latency observed in patients usually indexes decreased auditory discrimination.
► An MMN deficit may also index cognitive and functional decline shared by different disorders irrespective of their specific aetiology and symptomatology.
► MMN deficits index deficient N-methyl-d-aspartate (NMDA) receptor function affecting memory-trace formation and hence cognition in different disorders.