Mismatch Negativity Latency Research Articles

Reduced late mismatch negativity and auditory sustained potential to rule-based patterns in schizophrenia.

Complex rule-based auditory processing is abnormal in individuals with long-term schizophrenia (SZ), as demonstrated by reduced mismatch negativity (MMN) to deviants in rule-based patterns and reduced auditory sustained potential (ASP) that appears when grouping tones together. Together, this suggests deficits later in the auditory processing hierarchy in Sz. Here, MMN and ASP were elicited by deviations from a complex zig-zag pitch pattern that cannot be predicted by simple linear rules. Twenty-seven SZ and 26 matched healthy controls (HC) participated. Frequent groups of patterns contained eight tones that zig-zagged in a two-up one-down pitch-based paradigm. There were two deviant patterns: the final tone was either higher in pitch than expected (creating a jump in pitch) or was repeated. Simple MMN to pitch-deviants among repetitive tones was measured for comparison. Sz exhibited a smaller pitch MMN compared to HC as expected. HC produced a late MMN in response to the repeat and jump-deviant and a larger ASP to the standard group of tones, all of which were significantly blunted in SZ. In Sz, the amplitude of the late complex MMN was related to neuropsychological functioning, whereas ASP was not. ASP and late MMN did not significantly correlate in HC or in Sz, suggesting that they are not dependent on one another and may originate within distinct processing streams. Together, this suggests multiple deficits later in the auditory sensory-perceptual hierarchy in Sz, with impairments evident in both segmentation and deviance detection abilities.

Passive exposure to speech sounds modifies change detection brain responses in adults

In early life auditory discrimination ability can be enhanced by passive sound exposure. In contrast, in adulthood passive exposure seems to be insufficient to promote discrimination ability, but this has been tested only with a single short exposure session in humans. We tested whether passive exposure to unfamiliar auditory stimuli can result in enhanced cortical discrimination ability and change detection in adult humans, and whether the possible learning effect generalizes to different stimuli. To address these issues, we exposed adult Finnish participants to Chinese lexical tones passively for 2 h per day on 4 consecutive days. Behavioral responses and the brain's event-related potentials (ERPs) were measured before and after the exposure for the same stimuli applied in the exposure phase and to sinusoidal sounds roughly mimicking the frequency contour in speech sounds. Passive exposure modulated the ERPs to speech sound changes in both ignore (mismatch negativity latency, P3a amplitude and P3a latency) and attend (P3b amplitude) test conditions, but not the behavioral responses. Furthermore, effect of passive exposure transferred to the processing of the sinusoidal sounds as indexed by the latency of the mismatch negativity. No corresponding effects in the ERPs were found in a control group that participated to the test measurements, but received no exposure to the sounds. The results show that passive exposure to foreign speech sounds in adulthood can enhance cortical discrimination ability and attention orientation toward changes in speech sounds and that the learning effect can transfer to non-speech sounds.

Mismatch Negativity in Children: Reference Values.

Introduction The Mismatch Negativity (MMN) auditory evoked potential evaluation is a promising procedure to assess objectively the ability of auditory discrimination. Objective To characterize the latency and amplitude values of MMN in children with normal auditory thresholds and without auditory complaints. Methods Children between 5 and 11 years old participated in the present study. All participants underwent acoustic immittance measurements and tonal and vocal audiometry. The MMN was recorded with the MASBE ATC Plus system (Contronic, Pelotas, RS, Brazil). The electrodes were fixed in Fz (active electrode), Fpz (ground electrode) and in M2 and M1 (references electrodes). The intensity used was 80 dBHL, the frequent stimulus was 1,000 Hz and the rare stimulus was 2,000 Hz. The stimuli were presented in both ears separately. Results For the female group, the mean latencies and amplitude of MMN were 177.3 ms and 5.01 μV in the right ear (RE) and 182.4 ms and 5.39 μV in the left ear (LE). In the male group, the mean latencies were 194.4 ms in the RE and 183.6 ms in the LE, with an amplitude of 5.11 μV in the RE and 5.83 μV in the LE. There was no statistically significant difference between ears ( p = 0.867 - latency and p = 0.178 - amplitude), age ( p > 0.20) and the gender of the participants ( p > 0.05). Conclusion Using the described protocol, the mean latency value of MMN was 184.0 ms for RE and 182.9 ms for LE, and the amplitude was 5.05 μV and 5.56 μV for the left and right ears, respective.

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.

Effects of Gender and Apolipoprotein E on Novelty MMN and P3a in Healthy Elderly and Amnestic Mild Cognitive Impairment

Background: The apolipoprotein E epsilon4 (ApoE ε4) allele and female gender may be important risk factors for the development of Alzheimer’s disease and amnestic mild cognitive impairment (aMCI). Novelty mismatch negativity (MMN) represents the pre-attentive index of deviance detection and P3a represents the attention orienting response. Furthermore, MMN and P3a components have been reported to be potential markers in aMCI. Therefore, this study will investigate the effects of gender and ApoE on auditory novelty MMN and P3a and their relationship to neuropsychological performance in aMCI.Methods: Thirty nine aMCI subjects and 44 controls underwent neuropsychological assessment and ApoE genotyping. Novelty MMN and P3a components were investigated during an auditory novelty oddball task.Results: Firstly, novelty MMN latency was significantly shorter in aMCI than in healthy control (HC) group. Secondly, novelty MMN latency was negatively correlated with episodic memory in aMCI, but not in HC. Novelty P3a latency was negatively correlated with information processing speed in all subjects. For gender effect, novelty MMN latency was shorter in aMCI females than in HC females. Moreover, novelty P3a amplitudes were lower in males than in females in both aMCI and HC. For the effect of ApoE status, novelty MMN latency was shorter in aMCI ApoE ε4- than HC ApoE ε4-.Conclusion: aMCI presents altered pre-attentive processing indexed by novelty MMN components. Furthermore, there may be a compensatory mechanism on the impaired processing in aMCI. It further suggests that aMCI female and ApoE ε4- recruited the compensatory mechanism.

T52. Mismatch negativity in the diagnosis of Alzheimer disease

Dementia is the major health issue in aging society. Among which, Alzheimer disease is the leading cause of dementia. The accumulation of amyloid plague causes the possible neurotoxicity of the brain particularly in hippocampus area, which results in the short-term memory loss as the early clinical symptom of the Alzheimer disease. The abnormal plasticity related to the NMDA receptor lies in the underlying mechanism of functional abnormality. Mismatch negativity (MMN) is an event related potential reflecting the automatic novel detection in our brain which related to fronto-temporal circuits. It could be meliorated by the NMDA blockade. Here, we tried to use MMN as a biomarker for the detection of functional abnormality in Alzheimer disease. Total 25 healthy normal controls (6 Males and 19 Females) and 25 AD patients (10 Males and 15 Females) were completely collected. We recorded auditory MMN with four-deviant protocol with 32-channel EEG. Table 1 showed the individual MMSE score and profile of the patients. In Fig. 1, the MMN component was identified as the peak negative wave within the 150–250 ms latency range. We evaluated the peak amplitude and peak latency of MMN at the Fz electrode. Table 2 showed the average latency and amplitude of MMN in controls and dementia patients. A significant difference was noted in protocol 3 (p = 0.03, independent t-test) and a trend of significance in protocol 2 and 4 (p = 0.06, p = 0.07). Fig. 2 showed the relative change of normalized Mismatch Negativity amplitude in responsive to the protocol change. There was a trend of increasing ratio in normal subjects but not in dementia patients. In consistence with other papers, we found reduced MMN in dementia patients, which may related to abnormal NMDA related plasticity change due to short-term memory impairment. Of interest, we also found the increasing trend of normalized Mismatch Negativity amplitude in responsive to the protocol change in normal subjects but not in dementia patients. This novel results serve a possible biomarker in the detection of functional abnormality in dementia patients.

Amusia and its electrophysiological correlates in neurofibromatosis type 1.

Auditory processing deficits are common in people with neurofibromatosis type 1 (NF1) and they often report difficulties in musical performance. We investigated whether NF1 could be associated with amusia as well as with some impairment of primary auditory cortex activity. Eighteen people with NF1 and 22 healthy volunteers, matched for age, sex and educational level, were evaluated with the Montreal Battery Evaluation of Amusia - short version. The integrity of cortical primary auditory processing areas was evaluated by evoked potential mismatch negativity. Amusia was correlated with NF1 (p = 0.001, odds ratio = 42.0, confidence interval 4.5-39.6). Patients with NF1 exhibited a greater prevalence of amusia than healthy controls (67% vs. 4.5%) and difficulties in both melodic and temporal music perception. Worse performance on the Montreal Battery Evaluation of Amusia was correlated with a greater mismatch negativity latency in NF1 group. Amusia is a common feature in NF1 and may result from impairment of activity in primary auditory processing areas.

Saliency of Vowel Features in Neural Responses of Cochlear Implant Users.

Cochlear implants restore hearing in deaf individuals, but speech perception remains challenging. Poor discrimination of spectral components is thought to account for limitations of speech recognition in cochlear implant users. We investigated how combined variations of spectral components along two orthogonal dimensions can maximize neural discrimination between two vowels, as measured by mismatch negativity. Adult cochlear implant users and matched normal-hearing listeners underwent electroencephalographic event-related potentials recordings in an optimum-1 oddball paradigm. A standard /a/ vowel was delivered in an acoustic free field along with stimuli having a deviant fundamental frequency (+3 and +6 semitones), a deviant first formant making it a /i/ vowel or combined deviant fundamental frequency and first formant (+3 and +6 semitones /i/ vowels). Speech recognition was assessed with a word repetition task. An analysis of variance between both amplitude and latency of mismatch negativity elicited by each deviant vowel was performed. The strength of correlations between these parameters of mismatch negativity and speech recognition as well as participants' age was assessed. Amplitude of mismatch negativity was weaker in cochlear implant users but was maximized by variations of vowels' first formant. Latency of mismatch negativity was later in cochlear implant users and was particularly extended by variations of the fundamental frequency. Speech recognition correlated with parameters of mismatch negativity elicited by the specific variation of the first formant. This nonlinear effect of acoustic parameters on neural discrimination of vowels has implications for implant processor programming and aural rehabilitation.

Auditory Mismatch Negativity and P300a Elicited by the "Optimal" Multi-feature Paradigm in Early Schizophrenia.

The mismatch negativity (MMN) is an EEG-derived event-related potential (ERP) elicited by any violation of a predicted auditory "rule," regardless of whether one is attending to the stimuli and is thought to reflect updating of the stimulus context. Redirection of attention toward a rare, distracting stimulus event, however, can be measured by the subsequent P3a component of the P300. Chronic schizophrenia patients exhibit robust MMN deficits, as well as reductions in P3a amplitude. While, the substantial literature on the MMN in first-episode and early phase schizophrenia in this population reports reduced amplitudes, there also exist several contradictory studies. Conversely, P3a reduction in this population is relatively consistent, although the literature investigating this is small. The primary goal of this study was to contribute to our understanding of whether auditory change detection mechanisms are altered in early phase schizophrenia and, if so, under what conditions. Event-related potentials elicited by duration, frequency, gap, intensity, and location deviants (as elicited by the "optimal" multi-feature paradigm) were recorded in 14 early phase schizophrenia (EP) patients and 17 healthy controls (HCs). Electrical activity was recorded from 15 scalp electrodes. MMN/P3a amplitudes and latencies for each deviant were compared between groups and were correlated with clinical measures in EPs. There were no significant group differences for MMN amplitudes or latencies, though EPs did exhibit reduced P3a amplitudes to gap and duration deviants. Furthermore, PANSS (Positive and Negative Syndrome Scale) positive symptom scores were correlated with intensity MMN latencies and duration P3a amplitudes in EPs. These findings suggest that MMNs may not be as robustly reduced in early phase schizophrenia (relative to chronic illness), but that alterations may be more likely in patients with increased positive symptomatology. Furthermore, these findings offer further support to previous work suggesting that the understudied P3a may have good complementary utility as a marker of early cortical dysfunction in psychosis.

Effects of congenital blindness on the mismatch responses to Mandarin lexical tone, consonant, and vowel

With limited visual input, blind individuals rely more on auditory information to perceive the environmental stimuli. In this study, we investigated the effect of congenital blindness on the Mismatch Negativity (MMN) to Mandarin lexical tones, consonants and vowels using the oddball paradigm. The study included 9 congenitally blind subjects and 10 normal-sighted subjects without hearing impairment, while they are matched on age and verbal IQ. For lexical tone processing, no significant difference was observed between the two groups in MMN latencies or amplitudes, while both groups had larger Mandarin tone MMN on the right and central than on the left. For consonant processing, the MMN amplitude was larger on the left and central than the right only for blind participants, whereas MMN latencies of consonants in both groups were shorter on the right than the left. For vowel processing, blind group had longer MMN latencies than control group. These results suggested that blind individuals had similar pre-attentive lexical tone processing, but they relied more on the left and central hemisphere to differentiate consonants, and it took them more time automatically to process different vowels than the sighted individuals, possibly resulting from the compensatory mechanism of neural reorganization in blind subjects.

Emotional speech processing deficits in bipolar disorder: The role of mismatch negativity and P3a

BackgroundDeficits in emotional prosody processing have been observed in bipolar disorder (BD). While recent neural studies have explored impaired processing of facial expressions, little is known about deficits in emotional speech processing, or the specific stages of processing at which they occur. This study examined if pre-attentive detection and attention to emotional speech is impaired in BD, relative to healthy individuals. MethodsThe EEG data was collected from 14 individuals with BD and 14 healthy control (HC) participants while the auditory stimuli was presented via a passive three-stimulus oddball sequence which included emotionally (neutral, happy, sad) spoken syllables and acoustically matched nonvocal tones. Event-related potentials (ERPs) were evaluated in terms of Mismatch Negativity (MMN) and P3a (event-related potentials signals). ResultsIndividuals with BD showed normal MMN amplitude, but significantly delayed MMN latency and reduced P3a amplitude in response to the emotional syllables compared to HC. LimitationsSmall sample size, lack of control of psychopharmacological intervention and no inclusion of an affective prosody-labelling task. ConclusionsThe finding that changes in emotional speech prosody in the pre-attentive stages of processing (MMN) were unimpaired in individuals with BD; while automatic orientation towards emotionally salient speech (P3a) was reduced compared to HC, suggests that vocal emotional cues may not be recognised as salient by individuals with BD, resulting in fewer attentional resources allocation to further processing. This may lead to poorer integration of auditory emotional cues and other sensory information and negatively impact interpersonal and psychosocial functions.

Effects of Repetitive Transcranial Magnetic Stimulation Treatment on Event-Related Potentials in Schizophrenia

Background:Repetitive transcranial magnetic stimulation (rTMS) and event-related potentials (ERPs) are a noninvasive technique that widely used in neurophysiological field. Although rTMS has shown clinical utility for a number of neurological conditions, Recently, there was little understanding of the the efficacy of rTMS on Schizophrenia(SZ) and the change of ERP between before and after rTMS treatment. The objective of this study was to investigate the characteristics of N400, mismatch negativity (MMN), and P300 before and after treatment with rTMS in SZ.Methods:One hundred and twenty-seven SZ patients hospitalized in Shanghai Mental Health Center from March 2015 to July 2017, divided into two groups (85 patients were recruited as rTMS group and 42 were recruited as sham rTMS [ShrTMS] group) and 76 normal controls (NCs) who were the staff and refresher staff in our hospital were recruited at the same time. A Chinese-made rTMS and a Runjie WJ-1 ERPs instrument were used in the present experiment. N400 was elicited by congruent and noncongruent Chinese idioms. After rTMS treatment, N400, P300, and MMN characteristics were compared with those before treatment and NC group.Results:Compared with NC, the SZ patients exhibited delays in N400, P300, and MMN latency and decreased N400, P300, and MMN amplitudes in their frontal area (P < 0.05). After 25 rTMS treatments, N400 amplitudes in the frontal area (elicited by idioms with same phonic and different shape and meaning and with different phonic, shape, and meaning) were increased in the SZ patients (P < 0.05). However, there was no significant change in N400 before and after treatment with ShrTMS in SZ patients (P > 0.05). Amplitudes for MMN and target P300 also increased in SZ patients after rTMS treatment (P < 0.05).Conclusions:Based on our preliminary findings, we believe that the combined usage of N400, MMN, and P300 could be a valuable index and an electrophysiological reference in evaluating the effects of rTMS treatment in SZ patients.

Effects of Russian-Language Word Frequency on Mismatch Negativity in Auditory Event-Related Potentials

We report here our studied on the influence of the lexical frequency of Russian words on the latency and amplitude of mismatch negativity (MMN) in auditory event-related potentials (ERP). ERP were recorded in a multideviant oddball paradigm by presenting different-frequency Russian words and pseudowords. These experiments showed that the pattern of intrinsic MMN differed significantly between words with different lexical frequencies (p = 0.001) – the higher the frequency, the greater the amplitude and the shorter the latent period of the intrinsic MMN of the words. It is suggested that the greater amplitude and shorter latency of MMN for high-frequency words as compared with the pattern of MMN for low-frequency words is due to activation of memory traces for these words, these being stored in the cerebral cortex as distributed neuron populations. The suggestion that there is superfast access to lexical information during speech perception is confirmed, with access being possible 100–200 msec after presentation of a word. The ratio of MMN amplitudes for different pseudowords was somewhat reminiscent of data on MMN for words (analogs of high-frequency words produced higher-amplitude responses, while analogs of low-frequency words produced weaker responses, with no significant difference between low- and intermediate-frequency analogs), though MMN amplitudes for pseudowords were significantly greater and latent periods were significantly longer. Increases in the amplitude and latency of MMN to pseudowords as compared with MMN to words is associated with later and uncertain recognition of rarely encountered low-frequency words and completely unfamiliar stimuli, which are later classified as signals of a different category.

Effect of EEG Referencing Methods on Auditory Mismatch Negativity

Auditory event-related potentials (ERPs) have consistently been used in the investigation of auditory and cognitive processing in the research and clinical laboratories. There is currently no consensus on the choice of appropriate reference for auditory ERPs. The most commonly used references in auditory ERP research are the mathematically linked-mastoids (LM) and average referencing (AVG). Since LM and AVG referencing procedures do not solve the issue of electrically-neutral reference, Reference Electrode Standardization Technique (REST) was developed to create a neutral reference for EEG recordings. The aim of the current research is to compare the influence of the reference on amplitude and latency of auditory mismatch negativity (MMN) as a function of magnitude of frequency deviance across three commonly used electrode montages (16, 32, and 64-channel) using REST, LM, and AVG reference procedures. The current study was designed to determine if the three reference methods capture the variation in amplitude and latency of MMN with the deviance magnitude. We recorded MMN from 12 normal hearing young adults in an auditory oddball paradigm with 1,000 Hz pure tone as standard and 1,030, 1,100, and 1,200 Hz as small, medium and large frequency deviants, respectively. The EEG data recorded to these sounds was re-referenced using REST, LM, and AVG methods across 16-, 32-, and 64-channel EEG electrode montages. Results revealed that while the latency of MMN decreased with increment in frequency of deviant sounds, no effect of frequency deviance was present for amplitude of MMN. There was no effect of referencing procedure on the experimental effect tested. The amplitude of MMN was largest when the ERP was computed using LM referencing and the REST referencing produced the largest amplitude of MMN for 64-channel montage. There was no effect of electrode-montage on AVG referencing induced ERPs. Contrary to our predictions, the results suggest that the auditory MMN elicited as a function of increments in frequency deviance does not depend on the choice of referencing procedure. The results also suggest that auditory ERPs generated using REST referencing is contingent on the electrode arrays more than the AVG referencing.

Predicting Remission in Subjects at Clinical High Risk for Psychosis Using Mismatch Negativity.

The declining transition rate to psychotic disorder and the increasing rate of nonpsychotic poor outcomes among subjects at clinical high risk (CHR) for psychosis have increased the need for biomarkers to predict remission regardless of transition. This study investigated whether mismatch negativity (MMN) predicts the prognosis of CHR individuals during a 6-year follow-up period. A total of 47 healthy control (HC) subjects and 48 subjects at CHR for psychosis participated in the MMN assessment. The clinical statuses of the CHR subjects were examined at baseline and regularly for up to 6 years. The CHR subjects were divided into remitter and nonremitter groups, and the baseline MMN amplitudes and latencies were compared across the remitter, nonremitter, and HC groups. Regression analyses were performed to identify the predictive factors of remission, the improvement of attenuated positive symptoms, and functional recovery. CHR nonremitters showed reduced MMN amplitudes at baseline compared to CHR remitters and HC subjects. A logistic regression analysis revealed that the baseline MMN amplitude at the frontal electrode site was the only significant predictor of remission. In a multiple regression analysis, the MMN amplitude, antipsychotic use, and years of education predicted an improvement in attenuated positive symptoms. The MMN amplitude at baseline predicted functional recovery. These results suggest that MMN is a putative predictor of prognosis regardless of the transition to psychotic disorder in subjects at CHR. Early prognosis prediction and the provision of appropriate interventions based on the initial CHR status might be aided using MMN.

Dissociable auditory mismatch response and connectivity patterns in adolescents with schizophrenia and adolescents with bipolar disorder with psychosis: A magnetoencephalography study

BackgroundThere is overlap between schizophrenia and bipolar disorder regarding genetic risk as well as neuropsychological and structural brain deficits. Finding common and distinct event-response potential (ERP) responses and connectivity patterns may offer potential biomarkers to distinguish the disorders. ObjectiveTo examine the neuronal auditory response elicited by a roving mismatch negativity (MMN) paradigm using magnetoencephalography (MEG). Participants15 Adolescents with schizophrenia (ASZ), 16 adolescents with bipolar disorder with psychosis (ABP), and 14 typically developing individuals (TD) MethodsThe data were analysed using time-series techniques and dynamic causal modelling (DCM). Outcome measuresMEG difference wave (deviant – standard) at primary auditory (~90ms), MMN (~180ms) and long latency (~300ms). ResultsThe amplitude of difference wave showed specific patterns at all latencies. Most notably, it was significantly reduced ABP compared to both controls and ASZ at early latencies. In contrast, the amplitude was significantly reduced in ASZ compared to both controls and ABP. The DCM analysis showed differential connectivity patterns in all three groups. Most notably, inter-hemispheric connections were strongly dominated by the right side in ASZ only. ConclusionsDissociable patterns of the primary auditory response and MMN response indicate possible developmentally sensitive, but separate biomarkers for schizophrenia and bipolar disorder.

Lexical context affects mismatch negativity caused by pseudowords

The aim of this study was to investigate the effect of lexical context on the latency and the amplitude of the mismatch negativity (MMN) brain potential caused by perception of pseudowords. The eventrelated potentials were recorded according to the multideviant passive odd-ball paradigm by using only pseudowords (control condition) or pseudowords with Russian words with different lexical frequencies (lexical context). It was found that different MMN patterns were generated when the same pseudoword was presented in different contexts. Pseudoword presentation in a context with other pseudowords resulted in a relatively small amplitude and large latency of MMN. If the same pseudoword was presented in a context with words, it induced significantly increased amplitude and reduced latency of MMN varying in the range of 100–200 ms. It is supposed that the pseudoword presented in a context with words is perceived as conceptually different stimulus, which leads to a significant increase in MMN. Moreover, our findings support the hypothesis that MMN is affected by lexical frequency. In particular, presentation of a high-frequency word induced a significantly more pronounced MMN response than a low-frequency one. High-frequency words also evoked earlier response, which indicates more rapid access to a frequently used lexical entry. More frequent use of certain words results in stronger internal connections in the corresponding memory circuit, which in turn is determined by the lexical context. We hypothesize that different intensities of activation depends on the strength of lexical representation.

Musical rhythm and pitch: A differential effect on auditory dynamics as revealed by the N1/MMN/P3a complex

Music represents a complex form of human cognition. To what extent our auditory system is attuned to music is yet to be clearly understood. Our principal aim was to determine whether the neurophysiological operations underlying pre-attentive auditory change detection (N1 enhancement (N1e)/Mismatch Negativity (MMN)) and the subsequent involuntary attentional reallocation (P3a) towards infrequent sound omissions, are influenced by differences in musical content. Specifically, we intended to explore any interaction effects that rhythmic and pitch dimensions of musical organization may have over these processes. Results showed that both the N1e and MMN amplitudes were differentially influenced by rhythm and pitch dimensions. MMN latencies were shorter for musical structures containing both features. This suggests some neurocognitive independence between pitch and rhythm domains, but also calls for further address on possible interactions between both of them at the level of early, automatic auditory detection. Furthermore, results demonstrate that the N1e reflects basic sensory memory processes. Lastly, we show that the involuntary switch of attention associated with the P3a reflects a general-purpose mechanism not modulated by musical features. Altogether, the N1e/MMN/P3a complex elicited by infrequent sound omissions revealed evidence of musical influence over early stages of auditory perception.

Mismatch negativity is abnormal but not lateralizing in temporal lobe epilepsy.

We investigated the changes of mismatch negativity (MMN) in patients with temporal lobe epilepsy (TLE) and explored the possible role of MMN in lateralizing their seizure focus. Thirty patients with TLE and thirty healthy controls were included. MMN was elicited in each subject. Patients with TLE were divided into three subgroups: unilateral left TLE; unilateral right TLE, and bilateral TLE. MMN amplitudes and latencies were compared between the patients with TLE and the control group, and also among the three subgroups of TLE, using repeated measures analyses of variance (ANOVA). To assess the lateralizing value of MMN, MMN latencies and amplitudes at the mastoid sites between the ipsilateral and contralateral sides of epileptic focus in patients with unilateral TLE were compared using t-test. Compared with controls, each subgroup of patients with TLE had longer latencies of MMN at both fronto-central and mastoid sites, but the amplitudes of MMN were not significantly different. The amplitudes and latencies of MMN were not significantly different between the ipsilateral and contralateral sides of seizure focus at mastoid sites. The present findings of prolonged latencies of MMN are suggestive of cognitive impairment in TLE. Both the mastoid sites and the fronto-central sites are involved, which likely reflect widespread cortical abnormalities in TLE. However, the changes of MMN during the interictal phase are not useful for lateralizing the seizure focus in patients with TLE.

Associations between the mismatch-negativity component and symptom severity in children and adolescents with attention deficit/hyperactivity disorder.

AimCognitive impairment is an important predictor of functional outcome in patients with attention deficit/hyperactivity disorder (ADHD). However, the neurophysiology of ADHD-related cognitive impairments remains unclear. Event-related potentials (ERPs) represent the noninvasive measurement of neural correlates of cognitive function. Mismatch negativity (MMN) is an ERP component that is presumed to index the preattentive monitoring of changes in the auditory environment.Materials and methodsPrevious studies have shown altered MMN amplitude and latency in patients with ADHD. However, little is known about the relationship between MMN and ADHD-symptom severity. To address this, we measured the amplitude and latency of MMN in ERPs and assessed correlations with the clinical severity of ADHD, as measured by the ADHD Rating Scale IV – Japanese version. Participants were 51 treatment-naïve children and adolescents with ADHD (mean age 10.42±3.35 years) and 15 normally developing age- and sex-matched children (mean age 11.8±3.36 years).ResultsIn the ADHD group, MMN amplitudes were attenuated at the central electrode and MMN latencies prolonged at the parietal electrode (Pz) relative to those in the control group. Furthermore, MMN amplitudes at Pz were negatively correlated with ADHD full-scale and hyperactivity–impulsivity and inattention subscale scores, and MMN latency at Pz was positively correlated with ADHD hyperactivity–impulsivity subscale scores.ConclusionOur data suggest that MMN reflects the severity of ADHD symptoms in children and adolescents, and provides support for the use of ERPs in evaluating ADHD symptoms in patients.