Mismatch Negativity Duration Research Articles

Mismatch negativity in older adults and its relationship with the cognitive and behavioral aspects of central auditory processing

OBJECTIVES:This study aimed to describe and compare the performance of older adults with normal hearing and hearing impairments in mismatch negativity (MMN), correlate MMN with cognitive tasks and central auditory processing (CAP), and identify normal values for MMN in older adults.METHODS:This study had 54 participants. The Montreal Cognitive Assessment (MoCA) was used to assess cognition and the random gap detection test (RGDT), dichotic digit test (DDT), and speech to noise (SN) test were used to evaluate CAP. MMN was elicited with the verbal stimulus /da/ (frequent) and /ta/ (rare), and the latency, amplitude, duration, and area were analyzed.RESULTS:When comparing the normal-hearing group to those with hearing loss, there was no significant difference in MMN. When correlating MMN with MoCA, RGDT, DDT, and the SN test, there was a weak correlation between the MMN amplitude and the RGDT and DDT. When comparing the MMN of participants with normal and altered cognitive aspects and those with normal and altered DDT, the MMN duration was found to be affected by the DDT. The mean latency value of the MMN in the normal-hearing group was 199.8 ms, the amplitude was -2.2 µV, area was 116.1 µV/ms, and duration was 81.2 ms.CONCLUSION:Mild hearing loss did not influence MMN. There was no correlation between MMN and cognitive aspects, and there were weak correlations with CAP. Alterations in CAP led to longer durations in MMN. Normal values for MMN in adults aged between 60 and 77 years were generated.

The Relationship between Mismatch Negativity and the COMTVal108/158Met Genotype in Schizophrenia

Mismatch negativity (MMN) is a component of auditory event-related potentials that reflects automatic change detection in the brain, showing qualities of endophenotypes in schizophrenia. MMN deficiency is one of the robust findings in patients, and it reflects both cognitive and functional decline. Catechol-o-methyltransferase (COMT) is a key enzyme involved in regulating dopamine transmission within the prefrontal cortex. A preliminary study suggested that the COMTVal108/158Met genotype (rs4680) is related to cognitive function in schizophrenia. Both the COMTVal108/158Met genotype and MMN are related to cognitive function, but no studies have reported on the relationship between MMN and the COMTVal108/158Met genotype in schizophrenia. This study therefore examined the relationship between COMTVal108/158Met genotype and MMN. The duration of MMN was measured, and the COMTVal108/158Met polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism in 49 Japanese schizophrenia patients (Val/Val, n = 21; Met carriers, n = 28). Amplitude and latency of MMN were compared between Val/Val and Met carriers.

Cortical Encoding of Timbre Changes in Cochlear Implant Users

Most cochlear implant (CI) users describe music as a noise-like and unpleasant sound. Using behavioral tests, most prior studies have shown that perception of pitch-based melody and timbre is poor in CI users. This article will focus on cortical encoding of timbre changes in CI users, which may allow us to find solutions to further improve CI benefits. Furthermore, the value of using objective measures to reveal neural encoding of timbre changes may be reflected in this study. A case-control study of the mismatch negativity (MMN) using electrophysiological technique was conducted. To derive MMNs, three randomly arranged oddball paradigms consisting of standard/deviant instrumental pairs: saxophone/piano, cello/trombone, and flute/French horn, respectively, were presented. Ten CI users and ten normal-hearing (NH) listeners participated in this study. After filtering, epoching, and baseline correction, independent component analysis (ICA) was performed to remove artifacts. The averaged waveforms in response to the standard stimuli (STANDARD waveform) and the deviant stimuli (DEVIANT waveform) in each condition were separately derived. The responses from nine electrodes in the fronto-central area were averaged to form one waveform. The STANDARD waveform was subtracted from the DEVIANT waveform to derive the difference waveform, for which the MMN was judged to be present or absent. The measures used to evaluate the MMN included the MMN peak latency and amplitude as well as MMN duration. The MMN, which reflects the ability to automatically detect acoustic changes, was present in all NH listeners but only approximately half of CI users. In CI users with present MMNs, the MMN peak amplitude and duration were significantly smaller and shorter compared to those in NH listeners. Our electrophysiological results were consistent with prior behavioral results that CI users' performance in timbre perception was significantly poorer than that in NH listeners. Our results may suggest that timbre information is poorly registered in the auditory cortex of CI users and the capability of automatic detection of timbre changes is degraded in CI users. Although there are some limitations of the MMN in CI users, along with other objective auditory evoked potential tools, the MMN may be a useful objective tool to indicate the extent of sound registration in auditory cortex in the future efforts of improving CI design and speech strategy.