Mismatch Responses Research Articles

Double-epoch subtraction reveals long-latency mismatch response in urethane-anaesthetized mice

BackgroundAnaesthetized rodents are examined for their capacity to model human mismatch negativity (MMN). In the present study, oddball and deviant-alone control paradigms, with stimuli varying in frequency (ascending and descending) and intensity (louder and quieter), were presented to anaesthetized mice to determine whether they elicit a translational mismatch response (MMR). New methodResulting waveforms displayed long-latency (>200 ms post-stimulus) components, only made fully visible from oddball paradigm data by applying a double-epoch subtraction. In this approach, an extended epoch containing two consecutive standard evoked responses was subtracted from the response to an oddball followed by a standard (i.e. oddball:standard – standard:standard). ResultsThe trailing standard responses effectively cancelled each other out, revealing biphasic long-latency components. These MMR waveforms correlated strongly with deviant-alone paradigm evoked potentials >200 ms post-stimulus, potentially indicative of shared underlying mechanisms. Interestingly, these components were absent from the quieter oddball MMR. Comparison with existing method(s)Classical mismatch negativity computation is incapable of fully characterizing the long-latency biphasic response observed from this study, due to the inbuilt constraint of a single stimulus epoch. These results also suggest that the deviant-alone paradigm may be considered akin to a positive control for sensory-memory disruption, widely thought to be at the root of MMN generation in humans. ConclusionsLong-latency auditory evoked potential components are observed from anaesthetized mice in response to frequency and increasing intensity oddball stimuli. These display some congruencies with human MMN.

Prediction errors in surface segmentation are reflected in the visual mismatch negativity, independently of task and surface features.

The visual system quickly registers perceptual regularities in the environment and responds to violations in these patterns. Errors of perceptual prediction are associated with electrocortical modulation, including the visual mismatch negativity (vMMN) and P2 event-related potential. One relatively unexplored question is whether these prediction error signals can encode higher-level properties such as surface segmentation, or whether they are limited to lower-level perceptual features. Using a roving standard paradigm, a triangle surface appeared either behind (featuring amodal contours) or in front of (featuring real contours) a second surface with hole-like windows. A surface layout appeared for two to five repetitions before switching to the other "deviant" layout; lighting and orientation of stimuli varied across presentations while remaining isoluminant. Observers responded when they detected a rare "pinched" triangle, which occasionally appeared. Cortical activity-reflected in mismatch responses affecting the P2-N2 and P300 amplitudes-was sensitive to a change in stimulus layout, when surfaces shifted position in depth, following several repetitions. Specifically, layout deviants led to a more negative P2-N2 complex at posterior electrodes, and greater P300 positivity at central sites. Independently of these signals of a deviant surface layout, further modulations of the P2 encoded differences between layouts and detection of the rare target stimulus. Comparison of the effect of preceding layout repetitions on this prediction error signal suggests that it is all or none and not graded with respect to the number of previous repetitions. We show that within the visual domain, unnoticed and task-irrelevant changes in visual surface segmentation leads to observable electrophysiological signals of prediction error that are dissociable from stimulus-specific encoding and lower-level perceptual processing.

Fronto-parietal and temporal brain dysfunction in depression: A fMRI investigation of auditory mismatch processing.

Mismatch responses reflect neural mechanisms of early cognitive processing in the auditory domain. Disturbances of these mechanisms on multiple levels of neural processing may contribute to clinical symptoms in major depression (MD). A functional magnetic resonance imaging (fMRI) study was conducted to identify neurobiological foundations of altered mismatch processing in MD. Twenty-five patients with major depression and 25 matched healthy individuals completed an auditory mismatch paradigm optimized for fMRI. Brain activity during mismatch processing was compared between groups. Moreover, seed-based connectivity analyses investigated depression-specific brain networks. In patients, mismatch processing was associated with reduced activation in the right auditory cortex as well as in a fronto-parietal attention network. Moreover, functional coupling between the right auditory cortex and frontal areas was reduced in patients. Seed-to voxel analysis on the whole-brain level revealed reduced connectivity between the auditory cortex and the thalamus as well as posterior cingulate. The present study indicates deficits in sensory processing on the level of the auditory cortex in depression. Hyposensitivity in a fronto-parietal network presumably reflects altered attention mechanisms in depression. The observed impairments may contribute to psychopathology by reducing the ability of the affected individuals to orient attention toward important environmental cues.

Impact of Brain Injury on Processing of Emotional Prosodies in Neonates.

Being able to appropriately process different emotional prosodies is an important cognitive ability normally present at birth. In this study, we used event-related potential (ERP) to assess whether brain injury impacts the ability to process different emotional prosodies (happy, fear, and neutral) in neonates; whether the ERP measure has potential value for the evaluation of neurodevelopmental outcome in later childhood. A total of 42 full-term neonates were recruited from the neonatology department of Peking University First Hospital from June 2014 to January 2015. They were assigned to the brain injury group (n = 20) or control group (n = 22) according to their clinical manifestations, physical examinations, cranial images and routine EEG outcomes. Using an oddball paradigm, ERP data were recorded while subjects listened to happy (20%, deviation stimulus), fearful (20%, deviation stimulus) and neutral (80%, standard stimulus) prosodies to evaluate the potential prognostic value of ERP indexes for neurodevelopment at 30 months of age. Results showed that while the mismatch responses (MMRs) at the frontal lobe were larger for fearful than happy prosody in control neonates, this difference was not observed in neonates with brain injuries. This finding suggests that perinatal brain injury may influence the cognitive ability to process different emotional prosodies in neonatal brain; this deficit could be reflected by decreased MMR amplitudes in response to fearful prosody. Moreover, the decreased MMRs at the frontal lobe was associated with impaired neurodevelopment at 30 months old.

Does intra-uterine language experience modulate word stress processing? An ERP study

BackgroundPreterm birth is associated with various risks, including delayed or atypical language development. The prenatal start of prosodic tuning may affect the processing of word stress, an important suprasegmental feature of spoken utterances. AimOur study focused on the expected contribution of intra-uterine experience to word stress processing. We aimed to demonstrate the hypothesized effect of intra-uterine sound exposition on stress sensitivity. MethodWe recorded ERP responses of 34 preterm infants elicited by bisyllabic pseudo-words in two oddball conditions by switching the stress pattern (legal vs. illegal) and role (standard vs. deviant). ResultsThe mismatch responses found were synchronized to each syllable of the illegally stressed stimuli with no difference between pre- and full-term infants. However, the clear role of the preterm status was demonstrated by the exaggerated processing of the native stress information. The impact of intra-uterine exposure to prosody was confirmed by our finding that moderate-late preterm infants outperformed the very preterm ones. ConclusionIntra-uterine exposition to prosodic features appears to contribute to the emergence of stable long-term stress representation. When this tuning is missing it is considered a risk for the language acquisition process.

Abnormal development of early auditory processing in 22q11.2 Deletion Syndrome

The 22q11.2 Deletion Syndrome (22q11.2 DS) is one of the highest genetic risk factors for the development of schizophrenia spectrum disorders. In schizophrenia, reduced amplitude of the frequency mismatch negativity (fMMN) has been proposed as a promising neurophysiological marker for progressive brain pathology. In this longitudinal study in 22q11.2 DS, we investigate the progression of fMMN between childhood and adolescence, a vulnerable period for brain maturation. We measured evoked potentials to auditory oddball stimuli in the same sample of 16 patients with 22q11.2 DS and 14 age-matched controls in childhood and adolescence. In addition, we cross-sectionally compared an increased sample of 51 participants with 22q11.2 DS and 50 controls divided into two groups (8–14 and 14–20 years). The reported results are obtained using the fMMN difference waveforms. In the longitudinal design, the 22q11.2 deletion carriers exhibit a significant reduction in amplitude and a change in topographic patterns of the mismatch negativity response from childhood to adolescence. The same effect, reduced mismatch amplitude in adolescence, while preserved during childhood, is observed in the cross-sectional study. These results point towards functional changes within the brain network responsible for the fMMN. In addition, the adolescents with 22q11.2 DS displayed a significant increase in amplitude over central electrodes during the auditory N1 component. No such differences, reduced mismatch response nor increased N1, were observed in the typically developing group. These findings suggest different developmental trajectories of early auditory sensory processing in 22q11.2 DS and functional changes that emerge during the critical period of increased risk for schizophrenia spectrum disorders.

Phonological memory traces do not contain phonetic information

We use a "varying standards" oddball paradigm and compare two phonetically differing conditions to find evidence that the auditory cortex has access to discrete phonological representations when making predictions about incoming speech sounds. Brain responses were recorded with a 128-electrode EEG system as subjects passively listened to synthetic speech sounds from a /dæ/-/tæ/ continuum. Deviant stimuli were compared to a control condition to obtain a mismatch negativity (MMN) response, indicative of a "surprise" at a stimulus that deviates from the memory trace. We tested two conditions with phonetically different varying standards - a "low-T" condition with VOT values of 60, 65, and 70 ms, and a "high-T" condition with VOT values of 75, 80, and 85 ms. The amplitude of the mismatch response is generally sensitive to acoustic distance. If the memory trace generated by the auditory cortex contains phonetic information about the standards, then a difference in mismatch amplitude is expected. However, if a phonological memory trace is used, every standard will be represented identically and no difference in mismatch amplitude will be observed. We found no distance effect in our results, indicating an absence of fine-grained phonetic information. This supports the claim that the auditory cortex has access to phonological category representations.

Auditory white matter pathways are associated with effective connectivity of auditory prediction errors within a fronto-temporal network

Auditory prediction errors, i.e. the mismatch between predicted, forthcoming auditory sensations and actual sensory input, trigger the detection of surprising auditory events in the environment. Auditory mismatches engage a hierarchical functional network of cortical sources, which are also interconnected by auditory white matter pathways. Hence it is plausible that these structural and functional networks are quantitatively related. The present study set out to investigate whether structural connectivity of auditory white matter pathways enables the effective connectivity underpinning auditory mismatch responses. Participants (N = 89) underwent diffusion weighted magnetic resonance imaging (MRI) and electroencephalographic (EEG) recordings. Anatomically-constrained tractography was used to extract auditory white matter pathways, namely the bilateral arcuate fasciculi, inferior fronto-occipital fasciculi (IFOF), and the auditory interhemispheric pathway, from which Apparent Fibre Density (AFD) was calculated. EEG data were recorded in the same participants during a stochastic oddball paradigm, which was used to elicit auditory prediction error responses. Dynamic causal modelling was used to investigate the effective connectivity underlying auditory mismatch responses generated in brain regions interconnected by the above mentioned auditory white matter pathways. Our results showed that brain areas interconnected by all auditory white matter pathways best explained the dynamics of auditory mismatch responses. Furthermore, AFD in the right arcuate fasciculus was significantly associated with the effective connectivity between the cortical regions that lie within it. Taken together, these findings indicate that auditory prediction errors recruit a fronto-temporal network of brain regions that are effectively and structurally connected by auditory white matter pathways.

Perception of incongruent audiovisual English consonants.

Causal inference—the process of deciding whether two incoming signals come from the same source—is an important step in audiovisual (AV) speech perception. This research explored causal inference and perception of incongruent AV English consonants. Nine adults were presented auditory, visual, congruent AV, and incongruent AV consonant-vowel syllables. Incongruent AV stimuli included auditory and visual syllables with matched vowels, but mismatched consonants. Open-set responses were collected. For most incongruent syllables, participants were aware of the mismatch between auditory and visual signals (59.04%) or reported the auditory syllable (33.73%). Otherwise, participants reported the visual syllable (1.13%) or some other syllable (6.11%). Statistical analyses were used to assess whether visual distinctiveness and place, voice, and manner features predicted responses. Mismatch responses occurred more when the auditory and visual consonants were visually distinct, when place and manner differed across auditory and visual consonants, and for consonants with high visual accuracy. Auditory responses occurred more when the auditory and visual consonants were visually similar, when place and manner were the same across auditory and visual stimuli, and with consonants produced further back in the mouth. Visual responses occurred more when voicing and manner were the same across auditory and visual stimuli, and for front and middle consonants. Other responses were variable, but typically matched the visual place, auditory voice, and auditory manner of the input. Overall, results indicate that causal inference and incongruent AV consonant perception depend on salience and reliability of auditory and visual inputs and degree of redundancy between auditory and visual inputs. A parameter-free computational model of incongruent AV speech perception based on unimodal confusions, with a causal inference rule, was applied. Data from the current study present an opportunity to test and improve the generalizability of current AV speech integration models.

Non-speech and speech pitch perception among Cantonese-speaking children with autism spectrum disorder: An ERP study

The present study compared how Cantonese-speaking children with Autism Spectrum Disorder (ASD) and their typically developing counterparts perceived speech pitch and non-speech pitch information using ERP measurements. Sixteen children with ASD (mean age = 10.42 years, SD = 2.12 years) and sixteen normal controls (mean age = 9.48 years, SD =.86 years) participated in two experiments, in which Cantonese lexical tone contrasts and non-speech pitch variations were presented to children following an oddball paradigm when they watched a silent movie. The results showed that: 1) When processing speech pitch contour, the two groups did not differ in the amplitude of mismatch response (p-MMR), while typically developing controls showed larger mismatch negativity (MMN) responses than children with ASD. In the processing of speech pitch height, more positive p-MMR was observed among children with ASD than among normal controls and stronger MMN was found for typically developing children than for children with ASD. 2) For the processing of non-speech pitch, MMN rather than p-MMR was observed and the two groups did not differ significantly with each other in the amplitudes of MMN. These results indicated that Cantonese-speaking children with ASD manifested impaired ability when processing speech pitch information (i.e., lexical tone), which was in line with previous research. However, they did not show the advantage in processing non-speech or auditory pitch information, which was not in agreement with the previous studies. Results were discussed from the perspective of how language background (i.e., Cantonese) might shape the perceptive abilities of children.

Pre-attentive Mismatch Response and Involuntary Attention Switching to a Deviance in an Earlier-Than-Usual Auditory Stimulus: An ERP Study.

An acoustic stimulus elicits an electroencephalographic response called auditory event-related potential (ERP). When some members of a stream of standard auditory stimuli are replaced randomly by a deviant stimulus and this stream is presented to a subject who ignores the stimuli, two different ERPs to deviant and standard stimuli are recorded. If the ERP to standard stimuli is subtracted from the ERP to deviant stimuli, the difference potential (DP) waveform typically exhibits a series of negative-positive-negative deflections called mismatch negativity (MMN), P3a, and reorienting negativity (RON), which are associated with pre-attentive change detection, involuntary attention switching, and reorienting of attention, respectively. The aim of the present study was to investigate how these pre-attentive processes are affected if the change occurs earlier than its usual timing implied by isochronous standard stimuli. In the MMN paradigm employed, 15% of the standards were randomly replaced by deviant stimuli which differed either in their pitch, their earlier onset time, or in both. Event-related responses to these three deviants [timely pitch change (RTP), earlier onset (REO), earlier pitch change (REP)] and to standards (RS) were recorded from 10 reading subjects. To maintain identical stimulation histories for the responses subtracted from each other, “deviant-standard” difference potentials (DP) for “timely” and “early” pitch deviances were derived as follows: DPTP = RTP − RS and DPEP = REP − REO. Interestingly, the MMN components of the DPs to timely and early pitch deviances had similar amplitudes, indicating that regularity of stimulus timing does not provide any benefit for the pre-attentive auditory change detection mechanism. However, different scalp current density (SCD) dynamics of the MMN/P3a complexes, elicited by timely and early pitch deviances, suggested that an auditory change in a stimulus occurring earlier-than-usual initiates a faster and more effective call-for-attention and causes stronger attention switching than a timely change. SCD results also indicated that the temporal, frontal, and parietal MMN components are simultaneously present rather than emerging sequentially in time, supporting the MMN models based on parallel deviance processing in the respective cortices. Similarity of the RONs to timely and early pitch deviances indicated that reorienting of attention is of the same strength in two cases.

Auditory‐evoked potentials to changes in sound duration in urethane‐anaesthetized mice

Spectrotemporally complex sounds carry important information for acoustic communication. Among the important features of these sounds is the temporal duration. An event-related potential called mismatch negativity indexes auditory change detection in humans. An analogous response (mismatch response) has been found to duration changes in speech sounds in rats but not yet in mice. We addressed whether mice show this response, and, if elicited, whether this response is functionally analogous to mismatch negativity or whether adaptation-based models suffice to explain them. Auditory-evoked potentials were epidurally recorded above the mice auditory cortex. The differential response to the changes in a repeated human speech sound /a/ was elicited 53-259ms post-change (oddball condition). The differential response was observable to the largest duration change (from 200 to 110ms). Any smaller (from 200 to 120-180ms at 10ms steps) duration changes did elicit an observable response. The response to the largest duration change did not robustly differ in amplitude from the response to the change-inducing sound presented without its repetitive background (equiprobable condition). The findings suggest that adaptation may suffice to explain responses to duration changes in spectrotemporally complex sounds in anaesthetized mice. The results pave way for development of a variety of murine models of acoustic communication.

An extensive pattern of atypical neural speech-sound discrimination in newborns at risk of dyslexia

ObjectiveIdentifying early signs of developmental dyslexia, associated with deficient speech-sound processing, is paramount to establish early interventions. We aimed to find early speech-sound processing deficiencies in dyslexia, expecting diminished and atypically lateralized event-related potentials (ERP) and mismatch responses (MMR) in newborns at dyslexia risk. MethodsERPs were recorded to a pseudoword and its variants (vowel-duration, vowel-identity, and syllable-frequency changes) from 88 newborns at high or no familial risk. The response significance was tested, and group, laterality, and frontality effects were assessed with repeated-measures ANOVA. ResultsAn early positive and right-lateralized ERP component was elicited by standard pseudowords in both groups, the response amplitude not differing between groups. Early negative MMRs were absent in the at-risk group, and MMRs to duration changes diminished compared to controls. MMRs to vowel changes had significant laterality × group interactions resulting from right-lateralized MMRs in controls. ConclusionsThe MMRs of high-risk infants were absent or diminished, and morphologically atypical, suggesting atypical neural speech-sound discrimination. SignificanceThis atypical neural basis for speech discrimination may contribute to impaired language development, potentially leading to future reading problems.

Amount of speech exposure predicts vowel perception in four- to eight-month-olds

During the first year of life, infants shift their focus in speech perception from acoustic to linguistic information. This perceptual reorganization is related to exposure, and a direct relation has previously been demonstrated between amount of daily language exposure and mismatch response (MMR) amplitude to a native consonant contrast at around one year of age. The present study investigates the same relation between amount of speech exposure and MMR amplitude to a native vowel contrast at four to eight months of age. Importantly, the present study uses spectrally rotated speech in an effort to take general neural maturation into account. The amplitude of the part of the MMR that is tied specifically to speech processing correlates with amount of daily speech exposure, as estimated using the LENA system.

A preliminary study of auditory mismatch response on the day of cochlear implant activation in children with hearing aids prior implantation.

ObjectiveThe study aimed to explore the characteristics of auditory mismatch response (MMR) in hearing-impaired children on the day when the cochlear implant (CI) was started (power-up) and the speech processor was programmed, and to investigate the effects of wearing hearing aids (HAs) before cochlear implantation on the early stage of postoperative auditory cortex plasticity, providing some demonstrative data for the objective evaluation of postoperative early auditory ability in children who underwent cochlear implantation.MethodsThe participants were 34 children with profound sensorineural hearing loss, who underwent cochlear implantation. The classical passive Oddball paradigm was adopted, using a pair of vowels which only have different lexical tones. The standard stimulus was /a2/ and the devious stimulus was /a4/.Results1) On the day of CI activation, the auditory MMR has been elicited in 30 children; the MMR incidence was 88%. 2) We observed both positive and negative auditory MMR waveforms. And logistic regression analysis showed that it was influenced by the age at cochlear implantation. 3) The duration with HA before surgery significantly influenced the MMR latency. The children with longer duration of HA use have much earlier latency of MMR. 4) There was a significant positive correlation between the age at HA use initiation and MMR amplitude. Earlier initial HA use was associated with smaller amplitude.ConclusionsMMR in response to Mandarin lexical tone can be recorded in most pediatric patients who had experience with HA on the day of CI power up. MMR is closely associated with the age at cochlear implantation, duration of HA use, and the age at HA use initiation. Hearing-impaired children should wear HA as early as possible and ensure consistent usage.

Neural Indices of Vowel Discrimination in Monolingual and Bilingual Infants and Children.

To examine maturation of neural discriminative responses to an English vowel contrast from infancy to 4 years of age and to determine how biological factors (age and sex) and an experiential factor (amount of Spanish versus English input) modulate neural discrimination of speech. Event-related potential (ERP) mismatch responses (MMRs) were used as indices of discrimination of the American English vowels [ε] versus [I] in infants and children between 3 months and 47 months of age. A total of 168 longitudinal and cross-sectional data sets were collected from 98 children (Bilingual Spanish-English: 47 male and 31 female sessions; Monolingual English: 48 male and 42 female sessions). Language exposure and other language measures were collected. ERP responses were examined in an early time window (160 to 360 msec, early MMR [eMMR]) and late time window (400 to 600 msec, late MMR). The eMMR became more negative with increasing age. Language experience and sex also influenced the amplitude of the eMMR. Specifically, bilingual children, especially bilingual females, showed more negative eMMR compared with monolingual children and with males. However, the subset of bilingual children with more exposure to English than Spanish compared with those with more exposure to Spanish than English (as reported by caretakers) showed similar amplitude of the eMMR to their monolingual peers. Age was the only factor that influenced the amplitude of the late MMR. More negative late MMR was observed in older children with no difference found between bilingual and monolingual groups. Consistent with previous studies, our findings revealed that biological factors (age and sex) and language experience modulated the amplitude of the eMMR in young children. The early negative MMR is likely to be the mismatch negativity found in older children and adults. In contrast, the late MMR amplitude was influenced only by age and may be equivalent to the Nc in infants and to the late negativity observed in some auditory passive oddball designs.

Written-Word Concreteness Effects in Non-attend Conditions: Evidence From Mismatch Responses and Cortical Oscillations.

It has been widely reported that concrete words have processing advantages over abstract words in terms of speed and efficiency of processing, a phenomenon known as the concreteness effect. However, little is still known about the early time-course of processing concrete and abstract words and whether this concreteness effect can still persist in conditions where attention is not focused on the words presented (automatic processing). This study aimed to shed light on these issues by examining the electrophysiological brain responses to concrete and abstract words. While participants were engaged in a non-linguistic color tracking task presented in the center of the monitor screen, matched Chinese concrete and abstract single-character words appeared within a passive oddball paradigm, out of the focus of attention. In calculating visual Mismatch Negativity (vMMN), Event-related potentials (ERPs) to words of the same semantic category were compared when these words were presented as deviants and standards. Before 320 ms, both abstract and concrete words yielded vMMN with left-lateralized distribution, suggesting similar verbal processing at an initial processing stage. After 320 ms, only concrete words additionally elicited vMMN with a central distribution. Time frequency (TF) analysis of the results also revealed larger theta power increase (200–300 ms) and theta power phase locking (200–450 ms) for concrete than for abstract words. Interestingly, there was more alpha power decrease for abstract than for concrete words from 300 to 450 ms. This may reflect the greater difficulty in processing abstract meaning. Taken together, our ERP and TF results point to the existence of different neural mechanisms underlying non-attentive processing of abstract and concrete words.

Effect of blindness on mismatch responses to Mandarin lexical tones, consonants, and vowels

According to the hypothesis of auditory compensation, blind listeners are more sensitive to auditory input than sighted listeners. In the current study, we employed the passive oddball paradigm to investigate the effect of blindness on listeners’ mismatch responses to Mandarin lexical tones, consonants, and vowels. Twelve blind and twelve sighted age- and verbal IQ-matched adults with normal hearing participated in this study. Our results indicated that blind listeners possibly had a more efficient pre-attentive processing (shorter MMN peak latency) of lexical tones in the tone-dominant hemisphere (i.e., the right hemisphere); and that they exhibited greater sensitivity (larger MMN amplitude) when processing phonemes (consonants and/or vowels) at the pre-attentive stage in both hemispheres compared with sighted individuals. However, we observed longer MMN and P3a peak latencies during phoneme processing in the blind versus control participants, indicating that blind listeners may be slower in terms of pre-attentive processing and involuntary attention switching when processing phonemes. This could be due to a lack of visual experience in the production and perception of phonemes. In a word, the current study revealed a two-sided influence of blindness on Mandarin speech perception.

Computer-assisted reading intervention for children with sensorineural hearing loss using hearing aids: Effects on auditory event-related potentials and mismatch negativity

ObjectivesThe primary aim was to investigate whether computer-assisted reading intervention somehow can affect event-related potentials (ERP) and mismatch negativity (MMN) in hearing impaired (HI) children with hearing aids (HAs) and normal hearing (NH) children. MethodsThe study included 15 HI children with sensorineural hearing loss (SNHL) using bilateral HAs and 14 NH children as a reference group; all children between the ages of 5 and 8. A multi-feature MMN-paradigm, Optimum-1, with a standard stimulus alternating with 5 different deviants was used. ERPs were recorded pre and post intervention, i.e. one month of repeatedly computer-assisted training (GraphoGame). MMN was calculated from the average ERP of each deviant minus standard. Data were based on samples within a specific time interval, 80–224 ms, and repeated measures ANOVA was used to analyze possible interactions. ResultsThere was a significant difference between groups before training, though, the mean obligatory responses or MMN was not statistically significantly different before versus after training, neither among the NH nor the HI children. Further, the HI children did generally achieve lower levels in GraphoGame compared to the NH children. Altogether, our findings indicate differences between the groups and that training may affect the neurophysiological processing in the brain, gaining the HI children. Both MMN and positive mismatch response (pMMR) were seen among both the HA and NH children, irrespective to deviant type. Individually, changes of the MMN and pMMR after training seem unpredictable. ConclusionThere are statistically significant differences in both the obligatory responses in ERP and the MMNs between the NH and HI groups before the computer-assisted training. Though, these differences disappear after the intervention. This suggests possible training effects regarding the central auditory processing among the HI children.

Deviance detection is the dominant component of auditory contextual processing in the lateral superior temporal gyrus: A human ECoG study

Auditory contextual processing has been assumed to be based on a hierarchical structure consisting of the primary auditory cortex, superior temporal gyrus (STG), and frontal lobe. Recent invasive studies on mismatch negativity (MMN) have revealed functional segregation for auditory contextual processing such as neural adaptation in the primary auditory cortex and prediction in the frontal lobe. However, the role of the STG remains unclear. We obtained induced activity in the high gamma band as mismatch response (MMR), an electrocorticographic (ECoG) counterpart to scalp MMN, and the components of MMR by analyzing ECoG data from patients with refractory epilepsy in an auditory oddball task paradigm. We found that MMR localized mainly in the bilateral posterior STGs, and that deviance detection largely accounted for MMR. Furthermore, adaptation was identified in a limited number of electrodes on the superior temporal plane. Our findings reveal a mixed contribution of deviance detection and adaptation depending on location in the STG. Such spatial considerations could lead to further understanding of the pathophysiology of relevant psychiatric disorders.