Mismatch negativity in children with dyslexia speaking Indian languages

Relationship Between Temporal Pattern Perception Test and Mismatch Negativity in Children With Auditory Processing Disorder and Dyslexia

BACKGROUND AND OBJECTIVES

Mismatch negativity (MMN) is an objective test for assessing auditory function. The central auditory nervous system processes different stimuli in various ways. This can be assessed using MMN elicited with different stimuli in an "oddball" paradigm. This study evaluated temporal ordering skills using MMN with different durations of stimuli. This study aimed to determine the correlation between the results of the behavioral duration pattern test (DPT) with MMN in typically developing children versus children with dyslexia and auditory processing disorder (APD). Subjects and.

METHODS

Two groups of children participated in the study. The experimental group included 16 children with APD and dyslexia who had scored below the age-matched scores in the DPT. The control group consisted of 16 typically developing children with age-matched scores in the DPT. MMN was elicited using the same stimuli (250 ms and 500 ms) as that of the DPT in both groups. MMN latency, MMN amplitude, and area under the curve were measured in both groups.

RESULTS

Compared to the control group, children with APD and dyslexia showed increased MMN latency, reduced amplitude, and decreased area under the curve. There was a low correlation (r= -0.293, p<0.05) between MMN latency and DPT scores. The correlation between MMN amplitude and DPT scores was moderate (0.472, p<0.001). Furthermore, a strong correlation (0.536, p<0.001) between area under the curve and DPT scores was demonstrated.

CONCLUSIONS

MMN amplitude and MMN area under the curve could serve as valid indicators during assessment of temporal ordering in children with APD and dyslexia.

Verbal and Nonverbal Mismatch Negativity in Children with Typical Development: Variables Analysis

Introduction  Mismatch negativity (MMN) is a promising instrument for the investigation of different auditory disorders, as it does not need behavioral responses. Objective  To analyze the influence of the ear, gender and age variables in the MMN in children with typical development; and to compare the different measures of this potential, using verbal and nonverbal stimuli in the sample studied, providing reference values. Methods  Observational, descriptive, cross-sectional, quantitative study, with 23 children, aged from 5 to 11 years and 11 months old, divided by age group. Mismatch negativity was performed using verbal and nonverbal stimuli, and the data was analyzed by means of the statistical Student t -test. Results  No significant differences were noted for the ear, gender and age variables in the MMN with both stimuli. There were significant differences for the latency, duration and area variables when the stimuli were compared. The reference values established for nonverbal stimuli were: latency 249.8 milliseconds, amplitude 2.28 µv, duration 82.97 milliseconds, and area 137.3 microvolt x microseconds (μVx μs); as for the verbal stimuli, they were: latency 265.3 milliseconds, amplitude - 2.82 µv, duration 110.5 milliseconds, and area 225.5 microvolt x microseconds (μVx μs). Conclusion  The variables studied did not influence the recordings of the MMN. Latency, duration and area of the MMN with verbal stimuli were higher. It was possible to furnish reference values for children with typical development in the age group studied.

Auditory processing deficit in individuals with dyslexia: A meta-analysis of mismatch negativity

Several previous studies have used mismatch negativity (MMN) to examine the auditory processing deficit in individuals with dyslexia. However, researchers have not clearly determined whether the deficit is general or specific and how it potentially changes with age. Meta-analysis was adopted to quantitatively identify the auditory processing deficit in individuals with dyslexia. By analysing 81 results within 25 publications that employed passive oddball paradigms to explore auditory processing in individuals with dyslexia, we identified that MMN impairment in auditory processing of speech was observed in children (Cohen's d = 0.296) and adults with dyslexia (Cohen's d = 0.486). Besides, adults with dyslexia showed atypical auditory processing of non-speech (Cohen's d = 0.409), which appeared to be related to the types of stimuli. Based on these findings, for individuals with dyslexia, the auditory processing deficit in speech will persist into adulthood, and the auditory processing deficit is general in adults with dyslexia. Because few studies used appropriate non-speech stimuli to examine the auditory processing in children with dyslexia, future studies should focus more on this area.

Mismatch Negativity Elicited by Verbal and Nonverbal Stimuli: Comparison with Potential N1

Introduction  Mismatch negativity (MMN) is a long latency auditory evoked potential, represented by a negative wave, generated after the potential N1 and visualized in a resulting wave. Objective  To identify the time of occurrence of MMN after N1, elicited with verbal and nonverbal stimuli. Methods  Ninety individuals aged between 18 and 56 years old participated in the study, 39 of whom were male and 51 female, with normal auditory thresholds, at least 8 years of schooling, and who did not present auditory processing complaints. All of them underwent audiologic anamnesis, visual inspection of external auditory meatus, pure tone audiometry, speech audiometry, acoustic immittance measures and the dichotic sentence identification test as a screening for alterations in auditory processing, a requirement to participate in the sample. The MMN was applied with two different stimuli, with these being da/ta (verbal) and 750 Hz and 1,000 Hz (nonverbal). Results  There was a statistically significant difference between the latency values of the N1 potential and the MMN with the two stimuli, as well as between the MMN with verbal and nonverbal stimuli, and the latency of the MMN elicited with da/ta being greater than that elicited with 750 Hz and 1,000 Hz, which facilitated its visualization. Conclusion  The time of occurrence of MMN after the N1 elicited with verbal stimuli was 100.4 ms and with nonverbal stimuli 85.5 ms. Thus, the marking of the MMN with verbal stimuli proved to be more distant from N1 compared with the nonverbal stimuli.

Mismatch Negativity Occurrence with Verbal and Nonverbal Stimuli in Normal-Hearing Adults

Introduction  The mismatch negativity (MMN) is a long-latency auditory evoked potential related to a passive elicited auditory event.

Objective  To verify the occurrence of MMN with different stimuli, to describe reference values in normal-hearing adults with verbal and nonverbal stimuli and to compare them with each other, besides analyzing the latency, area, and amplitude regarding gender and between the ears.

Method  Normal-hearing individuals, aged between 18 and 59 years old, participated in the study. As inclusion criterion in the study, all of them underwent tone threshold audiometry, logoaudiometry, tympanometry, and the Dichotic Sentence Identification (DSI) test, and later the MMN with 4 different stimuli, being 2 verbal (da/ta and ba/di) and 2 nonverbal stimuli (750/1,000Hz and 750/4,000Hz), which are considered stimuli with low and high contrast.

Results  A total of 90 individuals composed the sample, being 39 males and 51 females, with an average age of 26.9 years old. In the analysis of the latency, amplitude, and area of the four stimuli between the ears, they were not considered statistically different. There was a significant difference between all of the stimuli in terms of latency, amplitude and area, with the highest latency found in da/ta, and the greatest amplitude and area in ba/di. Regarding gender, there was only difference in the latency of the da/ta stimulus.

Conclusion  The da/ta and 750/1,000Hz stimuli elicited the most MMN in the population of normal-hearing adults. Among the genders, there was difference only regarding the latency of the verbal stimulus da/ta, and there was no difference between the ears.

The Basis for Language Acquisition: Congenitally Deaf Infants Discriminate Vowel Length in the First Months after Cochlear Implantation

One main incentive for supplying hearing impaired children with a cochlear implant is the prospect of oral language acquisition. Only scarce knowledge exists, however, of what congenitally deaf children actually perceive when receiving their first auditory input, and specifically what speech-relevant features they are able to extract from the new modality. We therefore presented congenitally deaf infants and young children implanted before the age of 4 years with an oddball paradigm of long and short vowel variants of the syllable /ba/. We measured the EEG in regular intervals to study their discriminative ability starting with the first activation of the implant up to 8 months later. We were thus able to time-track the emerging ability to differentiate one of the most basic linguistic features that bears semantic differentiation and helps in word segmentation, namely, vowel length. Results show that already 2 months after the first auditory input, but not directly after implant activation, these early implanted children differentiate between long and short syllables. Surprisingly, after only 4 months of hearing experience, the ERPs have reached the same properties as those of the normal hearing control group, demonstrating the plasticity of the brain with respect to the new modality. We thus show that a simple but linguistically highly relevant feature such as vowel length reaches age-appropriate electrophysiological levels as fast as 4 months after the first acoustic stimulation, providing an important basis for further language acquisition.

Late, not early mismatch responses to changes in frequency are reduced or deviant in children with dyslexia: an event-related potential study

BACKGROUND

Developmental disorders of oral and written language have been linked to deficits in the processing of auditory information. However, findings have been inconsistent, both for behavioural and electrophysiological measures.

METHODS

In this study, we examined event-related potentials (ERPs) in 20 6- to 14-year-old children with developmental dyslexia and 20 age-matched controls, divided into younger (6-11 years, n = 10) and older (11-14 years, n = 10) age bands. We focused on early (mismatch negativity; MMN) and late (late discriminative negativity; LDN) conventional mismatch responses and associated measures derived from time-frequency analysis (inter-trial coherence and event-related spectral perturbation). Responses were elicited using an auditory oddball task, whereby a stream of 1000-Hz standards was interspersed with rare large (1,200 Hz) and small (1,030 Hz) frequency deviants.

RESULTS

Conventional analyses revealed no significant differences between groups in the size of the MMN to either large or small frequency deviants. However, the younger age band of children with dyslexia showed an enhanced inter-trial coherence in the theta frequency band over the time window corresponding to the MMN to small deviants. By contrast, these same children showed a reduced-amplitude LDN for the small deviants relative to their age-matched controls, whilst the older children with dyslexia showed a shorter and less intense period of event-related desynchronization over this time window.

CONCLUSIONS

Initial detection and discrimination of auditory frequency change appears normal or even enhanced in children with dyslexia. Rather, deficits in late-stage auditory processing appear to be a feature of this population.

Deficit in the preattentive processing of syllabic duration and VOT in children with dyslexia

The aim of this experiment was to examine the preattentive processing of syllables in 9-11-year-old children with dyslexia and matched controls using the Mismatch Negativity (MMN), an auditory Event-Related brain potential (ERP) related to preattentive discrimination. Children were presented with a sequence of syllables that included standards (the syllable "Ba") and deviants in vowel frequency, vowel duration and Voice Onset Time (VOT) that were either close to or far from the standard (Small and Large deviants). No between-group differences were found for frequency deviants. However, whilst normal-reading children showed larger MMNs to Large than to Small deviants in vowel duration and VOT, no such deviance size effect was found in children with dyslexia. These results are taken to indicate that the preattentive processing of vowel duration and VOT is impaired in children with dyslexia, with no impairment in the processing of vowel frequency deviants. By revealing processing deficits of both duration and VOT deviants, these results suggest a strong link between acoustical and phonological processing.

The mismatch negativity (MMN)--a unique window to disturbed central auditory processing in ageing and different clinical conditions

In this article, we review clinical research using the mismatch negativity (MMN), a change-detection response of the brain elicited even in the absence of attention or behavioural task. In these studies, the MMN was usually elicited by employing occasional frequency, duration or speech-sound changes in repetitive background stimulation while the patient was reading or watching videos. It was found that in a large number of different neuropsychiatric, neurological and neurodevelopmental disorders, as well as in normal ageing, the MMN amplitude was attenuated and peak latency prolonged. Besides indexing decreased discrimination accuracy, these effects may also reflect, depending on the specific stimulus paradigm used, decreased sensory-memory duration, abnormal perception or attention control or, most importantly, cognitive decline. In fact, MMN deficiency appears to index cognitive decline irrespective of the specific symptomatologies and aetiologies of the different disorders involved.

Cross-linguistic neuroimaging and dyslexia: a critical view

Recent neuro-cognitive theories of dyslexia presume that all dyslexics have the same type of brain abnormality irrespective of the particular writing system their language uses. In this article, we indicate how this presumption is inconsistent with cross-linguistic investigations of reading and dyslexia. There are two main issues. First, the information-processing requirements of reading vary greatly across different orthographies. Second, it is known that even within a single orthography there are different subtypes of dyslexia. Consequentially, it cannot be the case, not even within a single orthography let alone across orthographies, that all dyslexics have the same type of brain abnormality. Neuro-cognitive theorizing about dyslexia cannot afford to ignore these issues.

Fast multi-feature paradigm for recording several mismatch negativities (MMNs) to phonetic and acoustic changes in speech sounds

In this study, we addressed whether a new fast multi-feature mismatch negativity (MMN) paradigm can be used for determining the central auditory discrimination accuracy for several acoustic and phonetic changes in speech sounds. We recorded the MMNs in the multi-feature paradigm to changes in syllable intensity, frequency, and vowel length, as well as for consonant and vowel change, and compared these MMNs to those obtained with the traditional oddball paradigm. In addition, we examined the reliability of the multi-feature paradigm by repeating the recordings with the same subjects 1-7 days after the first recordings. The MMNs recorded with the multi-feature paradigm were similar to those obtained with the oddball paradigm. Furthermore, only minor differences were observed in the MMN amplitudes across the two recording sessions. Thus, this new multi-feature paradigm with speech stimuli provides similar results as the oddball paradigm, and the MMNs recorded with the new paradigm were reproducible.