Impaired mismatch negativity (MMN) generation in schizophrenia as a function of stimulus deviance, probability, and interstimulus/interdeviant interval

TLDR

Schizophrenia is a severe mental disorder marked by perceptual and cognitive disturbances, and event‑related potentials—particularly mismatch negativity (MMN), an auditory ERP reflecting echoic memory—have consistently revealed MMN deficits in patients. The study aims to examine how MMN generation in schizophrenia varies with deviant stimulus probability, interstimulus and interdeviant intervals, and pitch separation. MMN was elicited using an auditory oddball paradigm in which infrequent deviant tones interrupt a sequence of standard tones, and the study manipulated deviant probability, ISI, IDI, and pitch difference. Schizophrenia patients showed reduced MMN amplitude across most conditions, with the largest deficits occurring when MMN is normally largest, and the deficit pattern differed from that seen in Alzheimer’s, stroke, and alcohol intoxication.

Abstract

Schizophrenia is a severe mental disorder associated with disturbances in perception and cognition. Event-related potentials (ERP) provide a mechanism for evaluating potential mechanisms underlying neurophysiological dysfunction in schizophrenia. Mismatch negativity (MMN) is a short-duration auditory cognitive ERP component that indexes operation of the auditory sensory ('echoic') memory system. Prior studies have demonstrated impaired MMN generation in schizophrenia along with deficits in auditory sensory memory performance. MMN is elicited in an auditory oddball paradigm in which a sequence of repetitive standard tones is interrupted infrequently by a physically deviant ('oddball') stimulus. The present study evaluates MMN generation as a function of deviant stimulus probability, interstimulus interval, interdeviant interval and the degree of pitch separation between the standard and deviant stimuli. The major findings of the present study are first, that MMN amplitude is decreased in schizophrenia across a broad range of stimulus conditions, and second, that the degree of deficit in schizophrenia is largest under conditions when MMN is normally largest. The pattern of deficit observed in schizophrenia differs from the pattern observed in other conditions associated with MMN dysfunction, including Alzheimer's disease, stroke, and alcohol intoxication.