Mismatch negativity in patients with major depressive disorder: A meta-analysis

ObjectiveDeficits of mismatch negativity (MMN), a general index of echoic memory function, have been documented in patients with schizophrenia. However, it remains controversial whether patients with major depressive disorder (MDD) demonstrate MMN defects compared with healthy controls (HC).MethodsAfter screening 41 potential studies identified in PubMed and Medline, 13 studies consisting of 343 HC and 339 patients with MDD were included in the present meta-analysis. The effect sizes (Hedges’s g) with a random-effect and inverse-variance weighted model were estimated for the MMN amplitudes and latencies. The effects of different deviant types (i.e., frequency and duration) and of different illness stages (i.e., acute and chronic) on MMN were also examined.ResultsWe found that 1) MMN amplitudes (g = 1.273, p < 0.001) and latencies (g = 0.303, p = 0.027) to duration, but not frequency deviants, were significantly impaired in patients with MDD compared to HC; 2), acute patients exhibited lower MMN amplitudes (g = 1.735, p < 0.001) and prolonged MMN latencies (g = 0.461, p = 0.007) for the duration deviants compared to HC. Only the attenuated duration MMN amplitudes were detected in patients with chronic MDD (g = 0.822, p = 0.027); and 3) depressive symptoms did not significantly correlate with MMN responses.ConclusionsPatients with MDD demonstrated abnormal MMN responses to duration deviants compared to HC.SignificanceDuration MMN may constitute an electrophysiological indicator to differentiate HC from patients with MDD, particularly those in the acute stage.     

Mismatch Negativity (MMN) evoked by sound duration contrasts: An unexpected major effect of deviance direction on amplitudes

ObjectiveVerify and explore unexpected results suggesting an effect of deviance direction (shorter or longer deviants) on the amplitude of MMNs evoked by sound duration contrasts.MethodsMMNs were recorded using the oddball paradigm on ten adults. Four standard stimulus durations (100, 150, 200 and 250 ms) were used and deviants were 50% shorter or longer. Behavioral data (hit rates, d′, and reaction times) were collected after the electrophysiological sessions.ResultsMMNs were larger for short than for long deviants. There was no effect on MMN latencies. Hit rates and d′ data were almost at ceiling level for all conditions even for the longest standard – long deviant combination in which the MMN was abolished.ConclusionsWe argue that the deviance direction effect on MMN amplitudes can be explained by the delay between the moment of deviance detection and the end of the deviance quantification process.SignificanceA major effect of deviance direction on amplitudes was confirmed. This effect, which was confined to electrophysiological data, is to be taken into account when using duration contrasts to probe the processing of temporal information.     

Candidate Electrophysiological Endophenotypes of Hyper-Reactivity to Change in Autism

Although resistance to change is a main feature of autism, the brain processes underlying this aspect of the disorder remain poorly understood. The aims of this study were to examine neural basis of auditory change-detection in children with autism spectrum disorders (ASD; N = 27) through electrophysiological patterns (MMN, P3a) and to test whether these are quantitatively related to intolerance of change (using the BSE-R scale). ASD displayed significantly shorter MMN latency and larger P3a than controls, indicating a greater tendency to switch attention to deviant events. These electrophysiological abnormalities were significantly more marked in children who displayed greater difficulties in tolerating change. The atypical neurophysiological mechanism of change perception identified might thus be associated with one of the hallmark behavioural manifestations of autism.     

Finding the right control: The mismatch negativity under investigation

ObjectiveWhen investigating auditory perceptual regularity processing, mismatch negativity (MMN) is commonly used. MMN is computed as a difference signal between the event-related potentials (ERPs) elicited by repeated standard tones and rarely occurring deviant tones. This procedure leads to an underestimation of the N1 component elicited by standards compared to the N1 to deviants which might affect the MMN. Consequently, a random control design was previously introduced. This design, however, overestimates the N1 to the deviant. Here, we developed a new paradigm that avoids previous drawbacks.MethodsWe designed a regular cascadic sequence as a control to the deviant. ERPs were measured while presenting conventional oddball blocks (standards, deviants), random control blocks and a cascadic control block.ResultsMMN was observed in each difference signal. Regarding the N1, standards elicited smallest amplitudes. The N1 for the deviant and the cascadic control was comparable. The largest N1 was elicited by the random control.ConclusionStandards underestimate N1 refractoriness effects in the responses to deviants, while random control tones overestimate. Cascadic control tones, however, provide a reasonable estimation for the N1.SignificanceThe new cascadic control design is suitable to investigate auditory perceptual regularity processes while controlling for N1 refractoriness effects.     

Long-term auditory processing outcomes in early implanted young adults with cochlear implants: The mismatch negativity vs. P300 response

ObjectiveLong-term outcomes of early implanted, young adult cochlear implant (CI) users remain variable. We measured auditory discrimination by means of event-related potentials in this population to examine whether variability at the level of cortical auditory processing helps to explain speech abilities.MethodsUsing an auditory oddball paradigm, the P300 and Mismatch Negativity (MMN) were measured in 8 young adult CI users and 14 normal-hearing peers. We related P300 amplitude and latency to clinical speech perception scores in quiet and to duration of deafness.ResultsAll individuals showed P300 responses. The MMN response was less robust in both groups. There was no evidence for differences in P300 responses between CI users and controls. P300 amplitude was associated with speech perception scores (r = 0.70, p = .05) and duration of deafness (r = −0.83, p = .009).ConclusionsEarly CI implantation yields good auditory processing outcomes at young adult age and, in contrast to MMN, the P300 provides a robust measure for auditory processing on an individual level.SignificanceAt the cortical level, early implanted, long-term CI users have good auditory discrimination, leaving variability in implantation outcomes unexplained. This group provides unique insight into the long-term neurophysiological underpinnings of early implantation.     

The right profile: mismatch negativity in schizophrenia with and without auditory hallucinations as measured by a multi-feature paradigm.

ObjectiveTo examine pre-attentive acoustic change detection in schizophrenia patients with and without auditory hallucinations via mismatch negativity (MMN) extracted from a multi-feature paradigm.MethodsThis study examined the electroencephalograph (EEG)-derived MMN, recorded across 32 sites, in 12 hallucinating patients (HPs) with schizophrenia, 12 non-hallucinating patients (NPs) with schizophrenia and 12 healthy controls (HCs). MMN was recorded in response to a multi-feature MMN paradigm [Näätänen, R., et al., 2004. The mismatch negativity (MMN): towards the optimal paradigm. Clin. Neurophys. 115, 140–144] which employs frequency, duration, intensity, location and gap deviants. Differences in source localization were probed using standardized low resolution brain electromagnetic tomography (sLORETA).ResultsHPs showed significantly smaller MMNs to duration deviants compared to HCs and NPs, as well as smaller MMNs to intensity deviants compared to HCs. Regionalized differences between HCs and each of the patient groups were observed in response to frequency deviants. There were no significant group effects for location or gap deviants, or for MMN latency. Source localization using sLORETA showed no significant differences in MMN generator location across groups for any of the deviant stimuli.ConclusionsThe often-reported robust MMN deficit to duration deviants may be specific to schizophrenia patients afflicted with auditory hallucinations. Furthermore, by using symptom-specific groups, novel deficits of pre-attentive auditory processing, such as that observed to intensity deviants in HPs, may be revealed.SignificanceThe differential responding observed between both groups of patients with schizophrenia has implications for automatic processing within the auditory cortex of hallucinating patients and suggests that care must be taken when recruiting participants in studies involving schizophrenia to ensure consistent, replicable results.     

Early and late auditory event-related potentials in cognitively high functioning male adolescents with autism spectrum disorder

Event-related potentials (ERP) studies have offered diverging results in characterizing the basic nature of abnormal sensory processing and discrimination in autism spectrum disorders (ASDs). In the present study we report duration mismatch negativity (MMN) and later ERP components (P3a and P3b) derived from auditory odd-ball paradigms in a homogenous sample of cognitively high functioning male adolescents with ASD. We find significantly reduced frontal and temporal MMN amplitudes and no differences in P3a or P3b amplitudes or latencies compared to controls. These findings are in contrast to recent studies reporting enhanced ERP amplitudes to auditory stimuli, and are more in support of a weakened automatic auditory sensory processing as being central to the abnormal auditory behavioral responses commonly encountered in ASD.     

Changes in the duration and frequency of deviant stimuli engender different mismatch negativity patterns in temporal lobe epilepsy

Mismatch negativity (MMN) is an event-related potential (ERP) component that reflects preattentive sensory memory functions. Previous research revealed that MMN is generated by distinct sources in the frontal and temporal lobes. Event-related potential abnormalities have been shown in the vicinity of seizure foci in epilepsy. Additionally, no published study has investigated the MMN in response to variations in both frequency and duration deviants in patients with temporal lobe epilepsy (TLE). The aims of this study were to compare MMN changes between the frontocentral sites and the mastoid sites and to compare MMNs related to deviant stimuli with different durations and frequencies in patients with TLE. We recorded MMNs elicited by duration and frequency changes of deviant stimuli from 15 patients with TLE and 15 healthy control subjects. We found that mean MMN amplitudes related to duration deviants were lower in patients with TLE at the mastoid sites relative to controls, whereas the MMN amplitudes at the frontocentral sites did not differ between the two groups. There were no MMN differences related to frequency deviants between TLE subjects and controls at the frontocentral sites or the mastoid sites. Mismatch negativity parameters related to duration deviants did not correlate with those related to deviant frequencies in the group with TLE. The present findings suggest selective impairments among multiple mismatch generators in TLE and suggest that processing of temporal information of auditory stimuli is selectively disturbed in TLE. Changes in MMN amplitudes related to duration deviants at the mastoid sites may represent deficits in time-dependent processing in TLE.     

Alterations of mismatch negativity (MMN) in schizophrenia patients with auditory hallucinations experiencing acute exacerbation of illness

Auditory verbal hallucinations (AHs), or hearing 'voices', are one of the hallmark symptoms of patients with schizophrenia. The primary objective of this study was to compare hallucinating schizophrenia patients with respect to differences in deviance detection, as indexed by the auditory mismatch negativity (MMN). Patients were recruited during an acute psychotic episode requiring hospitalization, during which time symptoms of psychosis, including auditory hallucinations, are likely to be at their most severe. MMNs to duration, frequency, gap, intensity and location deviants (as elicited by the 'optimal' multi-feature paradigm) were recorded in 12 acutely ill schizophrenia patients (SZ) with persistent AHs and 15 matched healthy controls (HC). Electrical activity was recorded from 32 scalp electrodes. MMN amplitudes and latencies for each deviant were compared between groups and were correlated with trait (PSYRATS) and state measures of AH severity and Positive and Negative Syndrome Scale (PANSS) ratings in SZs. There were significant group differences for duration, gap, intensity and location MMN amplitudes, such that SZs exhibited reduced MMNs compared to HCs. Additionally, gap MMN amplitudes were correlated with measures of hallucinatory state and frequency of AHs, while location MMN was correlated with perceived location of AHs. In summary, this study corroborates previous research reporting a robust duration MMN deficit in schizophrenia, as well as reporting gap, intensity and location MMN deficits in acutely ill schizophrenia patients with persistent AHs. Additionally, MMN amplitudes were correlated with state and trait measures of AHs. These findings offer further support to previous work suggesting that the presence of auditory hallucinations may make a significant contribution to the widely reported MMN deficits in schizophrenia.     

Nicotine and the hallucinating brain: effects on mismatch negativity (MMN) in schizophrenia

Elevated smoking rates have been noted in schizophrenia, and it has been hypothetically attributed to nicotine's ameliorating abnormal brain processes in this illness. There is some preliminary evidence that nicotine may alter pre-attentive auditory change detection, as indexed by the EEG-derived mismatch negativity (MMN), but no previous study has examined what role auditory verbal hallucinations (AVH) may have on these effects. The objective of this study was to examine MMN-indexed acoustic change detection in schizophrenia (SZ) following nicotine administration and elucidate its association with AVH. Using a modified multi-feature paradigm, MMNs to duration, frequency and intensity deviants were recorded in 12 schizophrenia outpatients (SZ) with persistent AVHs following nicotine (6mg) and placebo administration. Electrical activity was recorded from 32 scalp electrodes; MMN amplitudes and latencies for each deviant were compared between treatments and were correlated with trait (PSYRATS) and state measures of AVH severity and Positive and Negative Syndrome Scale (PANSS) ratings. Nicotine administration resulted in a shortened latency for intensity MMN. Additionally, nicotine-related change in MMN amplitude was correlated with nicotine-related change in subjective measures of hallucinatory state. In summary, nicotine did not affect MMN amplitudes in schizophrenia patients with persistent AVHs, however this study reports accelerated auditory change detection to intensity deviants with nicotine in this group. Additionally, nicotine appeared to induce a generalized activation of the auditory cortex in schizophrenia, resulting in a concurrent increase in intensity MMN amplitude and subjective clarity of AVHs.     

Auditory mismatch negativity deficits in long-term heavy cannabis users

Mismatch negativity (MMN) is an auditory event-related potential indicating auditory sensory memory and information processing. The present study tested the hypothesis that chronic cannabis use is associated with deficient MMN generation. MMN was investigated in age- and gender-matched chronic cannabis users (n = 30) and nonuser controls (n = 30). The cannabis users were divided into two groups according to duration and quantity of cannabis consumption. The MMNs resulting from a pseudorandomized sequence of 2 × 900 auditory stimuli were recorded by 32-channel EEG. The standard stimuli were 1,000 Hz, 80 dB SPL and 90 ms duration. The deviant stimuli differed in duration (50 ms) or frequency (1,200 Hz). There were no significant differences in MMN values between cannabis users and nonuser controls in both deviance conditions. With regard to subgroups, reduced amplitudes of frequency MMN at frontal electrodes were found in long-term (≥8 years of use) and heavy (≥15 joints/week) users compared to short-term and light users. The results indicate that chronic cannabis use may cause a specific impairment of auditory information processing. In particular, duration and quantity of cannabis use could be identified as important factors of deficient MMN generation.     

Nocturnal sleep architecture in idiopathic hypersomnia: a systematic review and meta-analysis

BackgroundCurrent sleep medicine nosology places increased importance on nocturnal polysomnographic sleep recordings in the diagnosis of central nervous system disorders of hypersomnolence, particularly idiopathic hypersomnia (IH).ObjectiveDetermine what differences in sleep staging and architecture exist between IH and healthy controls using meta-analysis.MethodsSystematic review identified relevant studies that included nocturnal polysomnography data for IH and healthy control groups. Meta-analysis compared standardized mean differences (Hedge's g) for total sleep time (TST), sleep onset latency (SOL), sleep efficiency (SE), rapid eye movement (REM) sleep percentage, slow wave sleep (SWS) percentage, and REM latency (REML). Moderator analyses were also conducted for variables with significant heterogeneity among studies.ResultsThe meta-analysis included 10 studies. Relative to controls, IH demonstrated increased TST (pooled g = 0.92; 95% CI: 0.46 to 1.38, p < 0.0001) and REM percentage (pooled g = 0.36, 95% CI: 0.09 to 0.64, p = 0.01), decreased SOL (pooled g = −0.46; 95% CI: −0.81 to −0.12, p = 0.009) and SWS percentage (pooled g = −0.28, 95% CI: −0.50 to −0.07, p = 0.01), without significant differences in SE (pooled g = 0.03; 95% CI: −0.32 to 0.38, p = 0.86) or REML (pooled g = 0.14, 95% CI: −0.21 to 0.49, p = 0.42). Moderator analysis demonstrated a significant effect of sex on SE, with a higher proportion of women to men significantly predicting lower SE between in IH and controls (p < 0.0001).ConclusionsIH is associated with several changes in sleep staging and architecture relative to healthy persons, including alterations in REM and SWS not currently delineated in nosological constructs. Further research is indicated to clarify how these findings are related the pathophysiology of IH and related disorders.     

Domain-specific suppression of auditory mismatch negativity with transcranial direct current stimulation

ObjectiveTo evaluate the influence of frontal transcranial direct current stimulation (tDCS) on auditory mismatch negativity (MMN).MethodsMMN is an event related potential calculated by subtracting the amplitude of the evoked potentials in response to a “standard” stimulus from the evoked potentials produced by a rare “oddball” stimulus. Here we assessed the influence of anodal tDCS, cathodal tDCS or sham stimulation delivered over the right inferior frontal cortex on MMN in response to duration and frequency auditory deviants in 10 healthy subjects.ResultsMMN to frequency deviants was significantly reduced after anodal tDCS compared with sham or cathodal stimulation which did not change MMN to frequency deviants. Neither anodal nor cathodal tDCS had any effect on MMN to duration deviants.ConclusionsNon-invasive brain stimulation with tDCS can influence MMN. The differing networks known to be activated by duration and frequency deviants could account for the differential effect of tDCS on duration and frequency MMN.SignificanceNon-invasive brain stimulation could be a useful method to manipulate MMN for experimental purposes.     

Intraoperative Erb's Point-Vertex recording increases brainstem auditory evoked potential wave V amplitude

ObjectiveRecording derivations for intraoperative brainstem auditory evoked potential (BAEP) monitoring consist of a preauricular electrode referenced to Cz′. These derivations are prone to unfavorable signal amplitude. This study analyses whether an alternative noncephalic electrode positioned over ipsilateral Erb’s point, thereby generating a new Erb’s point-vertex recording derivation, improves BAEP recordings.MethodsElectrodes were placed preauricularly (A1/A2) and at left and right Erb’s point (EP1/EP2). They were referenced to Cz′. Click sound stimulation (80–95 dB above hearing level) was applied. At intraoperative baseline conditions, latencies and amplitudes of waves I–V of all derivations were analyzed.ResultsData of 30 patients (54 ± 15 years/17 females) with normal hearing or mild symmetrical presbycusis undergoing infratentorial surgeries (15 microvascular decompressions) were analyzed. Using EP1-Cz′/EP2-Cz′ derivations compared to A1-Cz′/A2-Cz′, amplitudes for wave IV (left +65%, p < 0.001; right +43%, p = 0.002) and wave V (left +54%, p < 0.001; right +48%, p < 0.001) were significantly increased. Only in the left (EP1) derivation, there was a tendency towards less reproducibility of wave I, resulting in a decrease of amplitude (−35%, p = 0.005).ConclusionsAdding an Erb’s point electrode derivation resulted in larger amplitudes of waves IV to V. whereas conventional preauricular or mastoid derivation is preferential for wave I assessment.SignificanceIncreased wave amplitudes facilitate detection of pathologically reduced wave forms (wave V in particular) which represents a significant advancement.     

Altered neocortical tactile but preserved auditory early change detection responses in Friedreich ataxia

ObjectiveTo study using magnetoencephalography (MEG) the spatio-temporal dynamics of neocortical responses involved in sensory processing and early change detection in Friedreich ataxia (FRDA).MethodsTactile (TERs) and auditory (AERs) evoked responses, and early neocortical change detection responses indexed by the mismatch negativity (MMN) were recorded using tactile and auditory oddballs in sixteen FRDA patients and matched healthy subjects. Correlations between the maximal amplitude of each response, genotype and clinical parameters were investigated.ResultsEvoked responses were detectable in all FRDA patients but one. In patients, TERs were delayed and reduced in amplitude, while AERs were only delayed. Only tactile MMN responses at the contralateral secondary somatosensory cortex were altered in FRDA patients. Maximal amplitudes of TERs, AERs and tactile MMN correlated with genotype, but did not correlate with clinical parameters.ConclusionsIn FRDA, the amplitude of tactile MMN responses at SII cortex are reduced and correlate with the genotype, while auditory MMN responses are not altered.SignificanceSomatosensory pathways and tactile early change detection are selectively impaired in FRDA.     

Auditory discrimination profiles of speech sound changes in 6-year-old children as determined with the multi-feature MMN paradigm

ObjectiveA linguistic multi-feature mismatch negativity (MMN) paradigm with five types of changes (vowel, vowel-duration, consonant, frequency (F0), and intensity) in Finnish syllables was used to determine speech-sound discrimination in 17 normally-developing 6-year-old children. The MMNs for vowel and vowel-duration were also recorded in an oddball condition in order to compare the two paradigms. Similar MMNs in the two paradigms would suggest that they tap the same processes. This would promote the usefulness of the more time-efficient multi-feature paradigm for future studies in children.MethodsMMNs to five deviant types were recorded in the multi-feature paradigm in which these deviants (total of 50%) were presented in an alternating fashion with standards (50%). An oddball condition with vowel and vowel-duration deviants served as a control.ResultsThe linguistic multi-feature paradigm elicited significant MMN responses to all changes used and the responses were comparable to the ones recorded with the traditional oddball paradigm. Compared to a previous adult study (Pakarinen S, Lovio R, Huotilainen M, Alku P, Näätänen R, Kujala T. Fast multi-feature paradigm for recording several mismatch negativities (MMNs) to phonetic and acoustic changes in speech sounds. Biol Psychol, submitted for publication), the MMN amplitudes seemed to be smaller and of longer latencies in general in children than in adults.ConclusionsThe new time-efficient paradigm can be used in studies addressing cortical speech-sound discrimination in young children.SignificanceThe multi-feature paradigm enables fast (20 min) recording of MMNs for five speech-sound features. In future, it might be useful in detecting abnormalities in speech discrimination profiles of children with possible language-related disorders.     

Duration and frequency mismatch negativity in schizophrenia.

OBJECTIVES: The aim of the present study was to elucidate the reasons for apparent inconsistencies in the schizophrenia literature with respect to the mismatch negativity (MMN) waveform of the event-related potential (ERP). While most previous research has shown that MMN is reduced in schizophrenia, there are a small number of studies reporting that frequency MMN is not reduced. METHODS: We recorded ERPs to auditory stimuli with different frequencies and durations from patients with schizophrenia (N = 14) and control subjects (N = 17) of similar age and sex. MMNs to small but discriminable frequency deviants were contrasted with large frequency deviants and duration deviants. RESULTS: Only the MMN to duration deviants was significantly reduced in patients, although there was evidence of a similar trend for large frequency deviants. CONCLUSIONS: The results together with a review of the frequency MMN literature suggest that there are 3 variables which are important in determining whether patients exhibit a reduced MMN to frequency deviants: deviant probability, degree of deviance and interstimulus interval. The results also indicated that patients with schizophrenia may have particular deficits in processing the temporal properties of auditory stimuli. This finding has implications for the pathophysiology of the disorder as time-dependent processing is reliant on the integrity of an extensive network of brain areas consisting of auditory cortex, areas of pre-frontal cortex, the basal ganglia and cerebellum.     

Temporal integration: intentional sound discrimination does not modulate stimulus-driven processes in auditory event synthesis

Objective: Our previous study showed that the auditory context could influence whether two successive acoustic changes occurring within the temporal integration window (approximately 200 ms) were pre-attentively encoded as a single auditory event or as two discrete events (Cogn Brain Res 12 (2001) 431). The aim of the current study was to assess whether top-down processes could influence the stimulus-driven processes in determining what constitutes an auditory event.Methods: Electroencepholagram (EEG) was recorded from 11 scalp electrodes to frequently occurring standard and infrequently occurring deviant sounds. Within the stimulus blocks, deviants either occurred only in pairs (successive feature changes) or both singly and in pairs. Event-related potential indices of change and target detection, the mismatch negativity (MMN) and the N2b component, respectively, were compared with the simultaneously measured performance in discriminating the deviants.Results: Even though subjects could voluntarily distinguish the two successive auditory feature changes from each other, which was also indicated by the elicitation of the N2b target-detection response, top-down processes did not modify the event organization reflected by the MMN response.Conclusions: Top-down processes can extract elemental auditory information from a single integrated acoustic event, but the extraction occurs at a later processing stage than the one whose outcome is indexed by MMN.Significance: Initial processes of auditory event-formation are fully governed by the context within which the sounds occur. Perception of the deviants as two separate sound events (the top-down effects) did not change the initial neural representation of the same deviants as one event (indexed by the MMN), without a corresponding change in the stimulus-driven sound organization.     

Duration mismatch negativity in biological relatives of patients with schizophrenia spectrum disorders.

BACKGROUND: One of the most consistent findings in schizophrenia research over the past decade is a reduction in the amplitude of an auditory event-related brain potential known as mismatch negativity (MMN), which is generated whenever a deviant sound occurs in a background of repetitive auditory stimulation. The reduced amplitude of MMN in schizophrenia was first observed for deviant sounds that differ in duration relative to background standard sounds, and similar findings have been observed for sounds that are deviant in frequency. The aim of this study was to determine whether first-degree relatives of schizophrenia patients show a similar reduction in MMN amplitude to duration deviants. METHODS: We measured MMN to duration increments (deviants 100 msec vs. standards 50 msec) in 22 medicated patients with a diagnosis in the schizophrenia spectrum, 17 individuals who were first-degree unaffected relatives of patients, and 21 healthy control subjects. RESULTS: Mismatch negativity amplitude was reduced in patients and relatives compared with control subjects. There were no significant differences between patients and relatives. In contrast, the subsequent positive component, P3a, was larger in relatives compared with patients. CONCLUSIONS: These findings suggest that a reduced MMN amplitude may be an endophenotype marker of the predisposition to schizophrenia.     

Evidence that the mismatch negativity to pattern violations does not vary with deviant probability

Objective

To determine whether the classic inverse relationship between the amplitude of the mismatch negativity (MMN) and deviant probability can be demonstrated to violations of a concrete rule pattern.

Methods

In Experiment 1, oddball and patterned auditory sequences were presented with high (p = 0.16) and rare (p = 0.02) deviant probability. In Experiment 2, a slightly different pattern was presented with high, moderate (p = 0.08), low (p = 0.04), and rare deviant probability. In Experiment 3, deviants in the patterns from Experiments 1 and 2 were actively detected at high and rare probability.

Results

In Experiment 1, the amplitude of the MMN varied inversely with deviant probability in both conditions. In Experiment 2, no effect of probability was observed. Experiment 3 supported the hypothesis that high deviant probability causes instability in the memory representation of the standard in the pattern from Experiment 1.

Conclusions

The amplitude of the MMN to concrete pattern violations does not vary with deviant probability.

Significance

The amplitude of the MMN may not vary with deviant probability. Once a stable memory representation is formed for the standard regularities in an auditory sequence, further examples may not strengthen that representation.