Abnormal Temporal Window of Integration in Auditory Sensory Memory in Schizophrenia

Mismatch negativity (MMN) is automatically elicited by incoming sound deviation compared to the neural representation of preceding homogenous sounds stored in the brain's auditory sensory memory. This study aimed to assess time-functional deviation sensitivity in auditory sensory memory associated with a temporal window of integration (TWI) of 160-170 msec in patients with schizophrenia. To this end, we measured the magnetic counterpart of the MMN (MMNm) in 20 patients with schizophrenia on medication and 20 healthy age-matched adults as a control group responding to an omitted tone segment incorporated into a complex sound of 176 ms duration corresponding to the TWI duration. Overall, the magnitude of the MMNm was smaller in the patients with schizophrenia than in the healthy control group. The peak latency of the MMNm was prolonged in the latter omitted segments for both groups, but to a greater extent in patients with schizophrenia. These results indicate that deviation detection is impaired in the later part of the TWI, corresponding to the duration of auditory sensory memory in patients with schizophrenia. Thus, the specific impairment of MMN in response to duration deviants (duration MMN), as previously reported, might result from a damaged mechanism in the later part of the TWI of sensory memory, suggesting that a decline in sensory memory causes distorted perception or disturbances in cognitive function in patients with schizophrenia.