The adaptive brain: A neurophysiological perspective

Phonemic mismatch negativity mediates the association between phoneme awareness and character reading ability in young Chinese children

Poor phonological awareness is associated with greater risk for reading disability. The underlying neural mechanism of such association may lie in the brain processing of phonological information. Lower amplitude of auditory mismatch negativity (MMN) has been associated with poor phonological awareness and with the presence of reading disability. The current study recorded auditory MMN to phoneme and lexical tone contrast with odd-ball paradigm and examined whether auditory MMN mediated the associations between phonological awareness and character reading ability through a three-year longitudinal study in 78 native Mandarin-speaking kindergarten children. Hierarchical linear regression and mediation analyses showed that the effect of phoneme awareness on the character reading ability was mediated by the phonemic MMN in young Chinese children. Findings underscore the key role of phonemic MMN as the underlying neurodevelopmental mechanism linking phoneme awareness and reading ability.

Prerequisites of language acquisition in the newborn brain

Learning to decode and produce speech is one of the most demanding tasks faced by infants. Nevertheless, infants typically utter their first words within a year, and phrases soon follow. Here we review cognitive abilities of newborn infants that promote language acquisition, focusing primarily on studies tapping neural activity. The results of these studies indicate that infants possess core adult auditory abilities already at birth, including statistical learning and rule extraction from variable speech input. Thus, the neonatal brain is ready to categorize sounds, detect word boundaries, learn words, and separate speech streams: in short, to acquire language quickly and efficiently from everyday linguistic input.

Neural phoneme discrimination in variable speech in newborns - Associations with dyslexia risk and later language skills

A crucial skill in infant language acquisition is learning of the native language phonemes. This requires the ability to group complex sounds into distinct auditory categories based on their shared features. Problems in phonetic learning have been suggested to underlie language learning difficulties in dyslexia, a developmental reading-skill deficit. We investigated auditory abilities important for language acquisition in newborns with or without a familial risk for dyslexia with electrophysiological mismatch responses (MMRs). We presented vowel changes in a sequence of acoustically varying vowels, requiring grouping of the stimuli to two phoneme categories. The vowel changes elicited an MMR which was significantly diminished in infants whose parents had the most severe dyslexia in our sample. Phoneme-MMR amplitude and its hemispheric lateralization were associated with language test outcomes assessed at 28 months, an age at which it becomes possible to behaviourally test children and several standardized tests are available. In addition, statistically significant MMRs to violations of a complex sound-order rule were only found in infants without dyslexia risk, but these results are very preliminary due to small sample size. The results demonstrate the relevance of the newborn infants' readiness for phonetic learning for their emerging language skills. Phoneme extraction difficulties in infants at familial risk may contribute to the phonological deficits observed in dyslexia.

Adapting to the Sound of Music - Development of Music Discrimination Skills in Recently Implanted CI Users

Cochlear implants (CIs) are optimized for speech perception but poor in conveying musical sound features such as pitch, melody, and timbre. Here, we investigated the early development of discrimination of musical sound features after cochlear implantation. Nine recently implanted CI users (CIre) were tested shortly after switch-on (T1) and approximately 3 months later (T2), using a musical multifeature mismatch negativity (MMN) paradigm, presenting four deviant features (intensity, pitch, timbre, and rhythm), and a three-alternative forced-choice behavioral test. For reference, groups of experienced CI users (CIex; n = 13) and normally hearing (NH) controls (n = 14) underwent the same tests once. We found significant improvement in CIre's neural discrimination of pitch and timbre as marked by increased MMN amplitudes. This was not reflected in the behavioral results. Behaviorally, CIre scored well above chance level at both time points for all features except intensity, but significantly below NH controls for all features except rhythm. Both CI groups scored significantly below NH in behavioral pitch discrimination. No significant difference was found in MMN amplitude between CIex and NH. The results indicate that development of musical discrimination can be detected neurophysiologically early after switch-on. However, to fully take advantage of the sparse information from the implant, a prolonged adaptation period may be required. Behavioral discrimination accuracy was notably high already shortly after implant switch-on, although well below that of NH listeners. This study provides new insight into the early development of music-discrimination abilities in CI users and may have clinical and therapeutic relevance.

The Neural Responses of Visual Complexity in the Oddball Paradigm: An ERP Study

This research measured human neural responses to images of different visual complexity levels using the oddball paradigm to explore the neurocognitive responses of complexity perception in visual processing. In the task, 24 participants (12 females) were required to react to images with high complexity for all stimuli. We hypothesized that high-complexity stimuli would induce early visual and attentional processing effects and may elicit the visual mismatch negativity responses and the emergence of error-related negativity. Our results showed that the amplitude of P1 and N1 were unaffected by complexity in the early visual processing. Under the target stimuli, both N2 and P3b components were reported, suggesting that the N2 component was sensitive to the complexity deviation, and the attentional processing related to complexity may be derived from the occipital zone according to the feature of the P3b component. In addition, compared with the low-complexity stimulus, the high-complexity stimulus aroused a larger amplitude of the visual mismatch negativity. The detected error negativity (Ne) component reflected the error detection of the participants’ mismatch between visual complexity and psychological expectations.

Evaluation of multi-feature auditory deviance detection in Parkinson's disease: a mismatch negativity study

Behavioral studies on auditory deviance detection in patients with Parkinson's disease (PD) have reported contradictory results. The primary aim of this study was to investigate auditory deviance detection of multiple auditory features in patients with PD by means of objective and reliable electroencephalographic (EEG) measurements. Twelve patients with early-stage PD and twelve age- and gender-matched healthy controls (HCs) were included in this study. Patients with PD participated without their regular dopaminergic medication. All subjects underwent an audiometric screening and performed a passive multi-feature mismatch negativity (MMN) paradigm. Repeated-measures analysis of variance (ANOVA) demonstrated no significant differences between patients with PD and HCs regarding MMN mean amplitude and latency for frequency, duration and gap deviants. Nevertheless, a trend towards increased MMN mean amplitude and latency was found in response to intensity deviants in patients with PD compared to HCs. Increased intensity MMN amplitude may indicate that more neural resources are allocated to the processing of intensity deviances in patients with PD compared to HCs. The interpretation of this intensity-specific MMN alteration is further discussed in the context of a compensatory mechanism for auditory intensity processing and involuntary attention switching in PD.

Cortical plasticity elicited by acoustically cued monetary losses: an ERP study

Both human and animal studies have demonstrated remarkable findings of experience-induced plasticity in the cortex. Here, we investigated whether the widely used monetary incentive delay (MID) task changes the neural processing of incentive cues that code expected monetary outcomes. We used a novel auditory version of the MID task, where participants responded to acoustic cues that coded expected monetary losses. To investigate task-induced brain plasticity, we presented incentive cues as deviants during passive oddball tasks before and after two sessions of the MID task. During the oddball task, we recorded the mismatch-related negativity (MMN) as an index of cortical plasticity. We found that two sessions of the MID task evoked a significant enhancement of MMN for incentive cues that predicted large monetary losses, specifically when monetary cue discrimination was essential for maximising monetary outcomes. The task-induced plasticity correlated with the learning-related neural activity recorded during the MID task. Thus, our results confirm that the processing of (loss)incentive auditory cues is dynamically modulated by previously learned monetary outcomes.

Suggested deafness during hypnosis and simulation of hypnosis compared to a distraction and control condition: A study on subjective experience and cortical brain responses

Hypnosis is a powerful tool to affect the processing and perception of stimuli. Here, we investigated the effects of hypnosis on the processing of auditory stimuli, the time course of event-related-potentials (ERP; N1 and P3b amplitudes) and the activity of cortical sources of the P3b component. Forty-eight participants completed an auditory oddball paradigm composed of standard, distractor, and target stimuli during a hypnosis (HYP), a simulation of hypnosis (SIM), a distraction (DIS), and a control (CON) condition. During HYP, participants were suggested that an earplug would obstruct the perception of tones and during SIM they should pretend being hypnotized and obstructed to hear the tones. During DIS, participants' attention was withdrawn from the tones by focusing participants' attention onto a film. In each condition, subjects were asked to press a key whenever a target stimulus was presented. Behavioral data show that target hit rates and response time became significantly reduced during HYP and SIM and loudness ratings of tones were only reduced during HYP. Distraction from stimuli by the film was less effective in reducing target hit rate and tone loudness. Although, the N1 amplitude was not affected by the experimental conditions, the P3b amplitude was significantly reduced in HYP and SIM compared to CON and DIS. In addition, source localization results indicate that only a small number of neural sources organize the differences of tone processing between the control condition and the distraction, hypnosis, and simulation of hypnosis conditions. These sources belong to brain areas that control the focus of attention, the discrimination of auditory stimuli, and the organization of behavioral responses to targets. Our data confirm that deafness suggestions significantly change auditory processing and perception but complete deafness is hard to achieve during HYP. Therefore, the term 'deafness' may be misleading and should better be replaced by 'hypoacusis'.

Early cortical processing of pitch height and the role of adaptation and musicality

Pitch is an important perceptual feature; however, it is poorly understood how its cortical correlates are shaped by absolute vs relative fundamental frequency (f₀), and by neural adaptation. In this study, we assessed transient and sustained auditory evoked fields (AEFs) at the onset, progression, and offset of short pitch height sequences, taking into account the listener's musicality. We show that neuromagnetic activity reflects absolute f₀ at pitch onset and offset, and relative f₀ at transitions within pitch sequences; further, sequences with fixed f₀ lead to larger response suppression than sequences with variable f₀ contour, and to enhanced offset activity. Musical listeners exhibit stronger f₀-related AEFs and larger differences between their responses to fixed vs variable sequences, both within sequences and at pitch offset. The results resemble prominent psychoacoustic phenomena in the perception of pitch contours; moreover, they suggest a strong influence of adaptive mechanisms on cortical pitch processing which, in turn, might be modulated by a listener's musical expertise.

Neuromagnetic speech discrimination responses are associated with reading-related skills in dyslexic and typical readers

Poor neural speech discrimination has been connected to dyslexia, and may represent phonological processing deficits that are hypothesized to be the main cause for reading impairments. Thus far, neural speech discrimination impairments have rarely been investigated in adult dyslexics, and even less by examining sources of neuromagnetic responses. We compared neuromagnetic speech discrimination in dyslexic and typical readers with mismatch fields (MMF) and determined the associations between MMFs and reading-related skills. We expected weak and atypically lateralized MMFs in dyslexic readers, and positive associations between reading-related skills and MMF strength. MMFs were recorded to a repeating pseudoword /ta-ta/ with occasional changes in vowel identity, duration, or syllable frequency from 43 adults, 21 with confirmed dyslexia. Phonetic (vowel and duration) changes elicited left-lateralized MMFs in the auditory cortices. Contrary to our hypothesis, MMF source strengths or lateralization did not differ between groups. However, better verbal working memory was associated with stronger left-hemispheric MMFs to duration changes across groups, and better reading was associated with stronger right-hemispheric late MMFs across speech-sound changes in dyslexic readers. This suggests a link between neural speech processing and reading-related skills, in line with previous work. Furthermore, our findings suggest a right-hemispheric compensatory mechanism for language processing in dyslexia. The results obtained promote the use of MMFs in investigating reading-related brain processes.

The Effect of Visual Articulatory Information on the Neural Correlates of Non-native Speech Sound Discrimination

Behavioral studies have shown that the ability to discriminate between non-native speech sounds improves after seeing how the sounds are articulated. This study examined the influence of visual articulatory information on the neural correlates of non-native speech sound discrimination. English speakers’ discrimination of the Hindi dental and retroflex sounds was measured using the mismatch negativity (MMN) event-related potential, before and after they completed one of three 8-min training conditions. In an audio-visual speech training condition (n = 14), each sound was presented with its corresponding visual articulation. In one control condition (n = 14), both sounds were presented with the same visual articulation, resulting in one congruent and one incongruent audio-visual pairing. In another control condition (n = 14), both sounds were presented with the same image of a still face. The control conditions aimed to rule out the possibility that the MMN is influenced by non-specific audio-visual pairings, or by general exposure to the dental and retroflex sounds over the course of the study. The results showed that audio-visual speech training reduced the latency of the MMN but did not affect MMN amplitude. No change in MMN amplitude or latency was observed for the two control conditions. The pattern of results suggests that a relatively short audio-visual speech training session (i.e., 8 min) may increase the speed with which the brain processes non-native speech sound contrasts. The absence of a training effect on MMN amplitude suggests a single session of audio-visual speech training does not lead to the formation of more discrete memory traces for non-native speech sounds. Longer and/or multiple sessions might be needed to influence the MMN amplitude.

Encoding of deterministic and stochastic auditory rules in the human brain: The mismatch negativity mechanism does not reflect basic probability

Regularities in a sequence of sounds can be automatically encoded in a predictive model by the auditory system. When a sound deviates from the one predicted by the model, a mismatch negativity (MMN) is elicited, which is taken to reflect a prediction error at a particular level of the model hierarchy. Although there are many studies on deterministic regularities, only a few have investigated the brain's ability to encode non-deterministic regularities. We studied a simple stochastic regularity: two tone pitches (standards, each occurring on 45% of trials); this regularity was occasionally violated by another tone pitch (deviant, occurring on 10% of trials). We found MMN when the deviant's pitch was outside those of the standards, but not when it was between them. Importantly, when we alternated the occurrence of the same two standards, making them deterministic, the deviant elicited MMN, even when its pitch was between those of the standards. Thus, although the MMN system is extremely powerful in establishing even quite complex deterministic regularities, it fails with a simple stochastic regularity. We argue that the MMN system does not know basic probability.

The Monetary Incentive Delay (MID) Task Induces Changes in Sensory Processing: ERP Evidence

Numerous cognitive studies have demonstrated experience-induced plasticity in the primary sensory cortex, indicating that repeated decisions could modulate sensory processing. In this context, we investigated whether an auditory version of the monetary incentive delay (MID) task could change the neural processing of the incentive cues that code expected monetary outcomes. To study sensory plasticity, we presented the incentive cues as deviants during oddball sessions recorded before and after training in the two MID task sessions. We found that after 2 days of training in the MID task, incentive cues evoked a larger P3a (compared with the baseline condition), indicating there was an enhancement of the involuntary attention to the stimuli that predict rewards. At the individual level, the training-induced change of mismatch-related negativity was correlated with the amplitude of the feedback-related negativity (FRN) recorded during the first MID task session. Our results show that the MID task evokes plasticity changes in the auditory system associated with better passive discrimination of incentive cues and with enhanced involuntary attention switching towards these cues. Thus, the sensory processing of incentive cues is dynamically modulated by previous outcomes.

Role of Thalamus in Recovery of Traumatic Brain Injury

Degree of recovery after traumatic brain injury is highly variable that lasts for many weeks to months. The evidence of brain structures involved in recovery mechanisms is limited. This review highlights evidence of the brain structure particularly thalamus in neuroplasticity mechanism. Thalamus with its complex global networking has potential role in refining the cortical and other brain structures. Thalamic nuclei activation both naturally or by neurorehabilitation in injured brain can enhance and facilitate the improvement of posttraumatic symptoms. This review provides evidence from literature that thalamus plays a key role in recovery mechanism after injury. The study also emphasize that thalamus should be specifically targeted in neurorehabilitation following brain injury.

The Role of Temporal Acoustic Exaggeration in High Variability Phonetic Training: A Behavioral and ERP Study

High variability phonetic training (HVPT) has been found to be effective in helping adult learners acquire non-native phonetic contrasts. The present study investigated the role of temporal acoustic exaggeration by comparing the canonical HVPT paradigm without involving acoustic exaggeration with a modified adaptive HVPT paradigm that integrated key temporal exaggerations in infant-directed speech (IDS). Sixty native Chinese adults participated in the training of the English /i/ and /i/ vowel contrast and were randomly assigned to three subject groups. Twenty were trained with the typical HVPT paradigm (the HVPT group), twenty were trained under the modified adaptive approach with acoustic exaggeration (the HVPT-E group), and twenty were in the control group. Behavioral tasks for the pre- and post- tests used natural word identification, synthetic stimuli identification, and synthetic stimuli discrimination. Mismatch negativity (MMN) responses from the HVPT-E group were also obtained to assess the training effects in within- and across- category discrimination without requiring focused attention. Like previous studies, significant generalization effects to new talkers were found in both the HVPT group and the HVPT-E group. The HVPT-E group, by contrast, showed greater improvement as reflected in larger progress in natural word identification performance. Furthermore, the HVPT-E group exhibited more native-like categorical perception based on spectral cues after training, together with corresponding training-induced changes in the MMN responses to within- and across- category differences. These data provide the initial evidence supporting the important role of temporal acoustic exaggeration with adaptive training in facilitating phonetic learning and promoting brain plasticity at the perceptual and pre-attentive neural levels.

Atypical perceptual and neural processing of emotional prosodic changes in children with autism spectrum disorders

OBJECTIVE

The present study explored the processing of emotional speech prosody in school-aged children with autism spectrum disorders (ASD) but without marked language impairments (children with ASD [no LI]).

METHODS

The mismatch negativity (MMN)/the late discriminative negativity (LDN), reflecting pre-attentive auditory discrimination processes, and the P3a, indexing involuntary orienting to attention-catching changes, were recorded to natural word stimuli uttered with different emotional connotations (neutral, sad, scornful and commanding). Perceptual prosody discrimination was addressed with a behavioral sound-discrimination test.

RESULTS

Overall, children with ASD (no LI) were slower in behaviorally discriminating prosodic features of speech stimuli than typically developed control children. Further, smaller standard-stimulus event related potentials (ERPs) and MMN/LDNs were found in children with ASD (no LI) than in controls. In addition, the amplitude of the P3a was diminished and differentially distributed on the scalp in children with ASD (no LI) than in control children.

CONCLUSIONS

Processing of words and changes in emotional speech prosody is impaired at various levels of information processing in school-aged children with ASD (no LI).

SIGNIFICANCE

The results suggest that low-level speech sound discrimination and orienting deficits might contribute to emotional speech prosody processing impairments observed in ASD.

Influence of Musical Enculturation on Brain Responses to Metric Deviants

The ability to recognize metric accents is fundamental in both music and language perception. It has been suggested that music listeners prefer rhythms that follow simple binary meters, which are common in Western music. This means that listeners expect odd-numbered beats to be strong and even-numbered beats to be weak. In support of this, studies have shown that listeners exposed to Western music show stronger novelty and incongruity related P3 and irregularity detection related mismatch negativity (MMN) brain responses to attenuated odd- than attenuated even-numbered metric positions. Furthermore, behavioral evidence suggests that music listeners' preferences can be changed by long-term exposure to non-Western rhythms and meters, e.g., by listening to African or Balkan music. In our study, we investigated whether it might be possible to measure effects of music enculturation on neural responses to attenuated tones on specific metric positions. We compared the magnetic mismatch negativity (MMNm) to attenuated beats in a “Western group” of listeners (n = 12) mainly exposed to Western music and a “Bicultural group” of listeners (n = 13) exposed for at least 1 year to both Sub-Saharan African music in addition to Western music. We found that in the “Western group” the MMNm was higher in amplitude to deviant tones on odd compared to even metric positions, but not in the “Bicultural group.” In support of this finding, there was also a trend of the “Western group” to rate omitted beats as more surprising on odd than even metric positions, whereas the “Bicultural group” seemed to discriminate less between metric positions in terms of surprise ratings. Also, we observed that the overall latency of the MMNm was significantly shorter in the Bicultural group compared to the Western group. These effects were not biased by possible differences in rhythm perception ability or music training, measured with the Musical Ear Test (MET). Furthermore, source localization analyses suggest that auditory, inferior temporal, sensory-motor, superior frontal, and parahippocampal regions might be involved in eliciting the MMNm to the metric deviants. These findings suggest that effects of music enculturation can be measured on MMNm responses to attenuated tones on specific metric positions.

Distinct ERP profiles for auditory processing in infants at-risk for autism and language impairment

Early identification of autism spectrum disorder (ASD) is crucial for the formulation of effective intervention programs. Language deficits may be a hallmark feature of ASD and language delay observed in ASD shows striking similarities to that observed in children with language impairment (LI). Auditory processing deficits are seen in both LI and ASD, however, they have not previously been compared directly using Event-Related Potentials (ERPs) in the two at-risk populations. This study aims to characterize infants at-risk for ASD (HR-ASD) at the electrophysiological level and to compare them with infants at-risk for LI (HR-LI) and controls, to find specific markers with predictive value. At 12-month-old, auditory processing in HR-ASD, HR-LI and controls was characterized via ERP oddball paradigm. All infants were then evaluated at 20 months, to investigate the associations between auditory processing and language/ASD-related outcomes. In both HR-ASD and HR-LI, mismatch response latency was delayed compared to controls, whereas only HR-ASD showed overall larger P3 amplitude compared to controls. Interestingly, these ERP measures correlated with later expressive vocabulary and M-CHAT critical items in the whole sample. These results may support the use of objective measurement of auditory processing to delineate pathophysiological mechanisms in ASD, as compared to LI.

Neural discrimination of speech sound changes in a variable context occurs irrespective of attention and explicit awareness

To process complex stimuli like language, our auditory system must tolerate large acoustic variance, like speaker variability, and still be sensitive enough to discriminate between phonemes and to detect complex sound relationships in, e.g., prosodic cues. Our study determined discrimination of speech sounds in input mimicking natural speech variability, and detection of deviations in regular pitch relationships (rule violations) between speech sounds. We investigated the automaticity and the influence of attention and explicit awareness on these changes by recording the neurophysiological mismatch negativity (MMN) and P3a as well as task performance from 21 adults. The results showed neural discrimination of phonemes and rule violations as indicated by MMN and P3a, regardless of whether the sounds were attended or not, even when participants could not explicitly describe the rule. While small sample size precluded statistical analysis of some outcomes, we still found preliminary associations between the MMN amplitudes, task performance, and emerging explicit awareness of the rule. Our results highlight the automaticity of processing complex aspects of speech as a basis for the emerging conscious perception and explicit awareness of speech properties. While MMN operates at the implicit processing level, P3a appears to work at the borderline of implicit and explicit.

Using rotated speech to approximate the acoustic mismatch negativity response to speech

The mismatch negativity (MMN) response is influenced by the magnitude of the acoustic difference between standard and deviant, and the response is typically larger to linguistically relevant changes than to linguistically irrelevant changes. Linguistically relevant changes between standard and deviant typically co-occur with differences between the two acoustic signals. It is therefore not straightforward to determine the contribution of each of those two factors to the MMN response. This study investigated whether spectrally rotated speech can be used to determine the impact of the acoustic difference on the MMN response to a combined linguistic and acoustic change between standard and deviant. Changes between rotated vowels elicited an MMN of comparable amplitude to the one elicited by a within-category vowel change, whereas the between-category vowel change resulted in an MMN amplitude of greater magnitude. A change between rotated vowels resulted in an MMN ampltude more similar to that of a within-vowel change than a complex tone change did. This suggests that the MMN amplitude reflecting the acoustic difference between two speech sounds can be well approximated by the MMN amplitude elicited in response to their rotated counterparts, in turn making it possible to estimate the part of the response specific to the linguistic difference.

Low-level neural auditory discrimination dysfunctions in specific language impairment-A review on mismatch negativity findings

In specific language impairment (SLI), there is a delay in the child’s oral language skills when compared with nonverbal cognitive abilities. The problems typically relate to phonological and morphological processing and word learning. This article reviews studies which have used mismatch negativity (MMN) in investigating low-level neural auditory dysfunctions in this disorder. With MMN, it is possible to tap the accuracy of neural sound discrimination and sensory memory functions. These studies have found smaller response amplitudes and longer latencies for speech and non-speech sound changes in children with SLI than in typically developing children, suggesting impaired and slow auditory discrimination in SLI. Furthermore, they suggest shortened sensory memory duration and vulnerability of the sensory memory to masking effects. Importantly, some studies reported associations between MMN parameters and language test measures. In addition, it was found that language intervention can influence the abnormal MMN in children with SLI, enhancing its amplitude. These results suggest that the MMN can shed light on the neural basis of various auditory and memory impairments in SLI, which are likely to influence speech perception.

Noise Equally Degrades Central Auditory Processing in 2- and 4-Year-Old Children

PURPOSE

The aim of this study was to investigate developmental and noise-induced changes in central auditory processing indexed by event-related potentials in typically developing children.

METHOD

P1, N2, and N4 responses as well as mismatch negativities (MMNs) were recorded for standard syllables and consonants, frequency, intensity, vowel, and vowel duration changes in silent and noisy conditions in the same 14 children at the ages of 2 and 4 years.

RESULTS

The P1 and N2 latencies decreased and the N2, N4, and MMN amplitudes increased with development of the children. The amplitude changes were strongest at frontal electrodes. At both ages, background noise decreased the P1 amplitude, increased the N2 amplitude, and shortened the N4 latency. The noise-induced amplitude changes of P1, N2, and N4 were strongest frontally. Furthermore, background noise degraded the MMN. At both ages, MMN was significantly elicited only by the consonant change, and at the age of 4 years, also by the vowel duration change during noise.

CONCLUSIONS

Developmental changes indexing maturation of central auditory processing were found from every response studied. Noise degraded sound encoding and echoic memory and impaired auditory discrimination at both ages. The older children were as vulnerable to the impact of noise as the younger children.

SUPPLEMENTAL MATERIALS

https://doi.org/10.23641/asha.5233939.

Sound-Making Actions Lead to Immediate Plastic Changes of Neuromagnetic Evoked Responses and Induced β-Band Oscillations during Perception

Auditory and sensorimotor brain areas interact during the action-perception cycle of sound making. Neurophysiological evidence of a feedforward model of the action and its outcome has been associated with attenuation of the N1 wave of auditory evoked responses elicited by self-generated sounds, such as talking and singing or playing a musical instrument. Moreover, neural oscillations at β-band frequencies have been related to predicting the sound outcome after action initiation. We hypothesized that a newly learned action-perception association would immediately modify interpretation of the sound during subsequent listening. Nineteen healthy young adults (7 female, 12 male) participated in three magnetoencephalographic recordings while first passively listening to recorded sounds of a bell ringing, then actively striking the bell with a mallet, and then again listening to recorded sounds. Auditory cortex activity showed characteristic P1-N1-P2 waves. The N1 was attenuated during sound making, while P2 responses were unchanged. In contrast, P2 became larger when listening after sound making compared with the initial naive listening. The P2 increase occurred immediately, while in previous learning-by-listening studies P2 increases occurred on a later day. Also, reactivity of β-band oscillations, as well as θ coherence between auditory and sensorimotor cortices, was stronger in the second listening block. These changes were significantly larger than those observed in control participants (eight female, five male), who triggered recorded sounds by a key press. We propose that P2 characterizes familiarity with sound objects, whereas β-band oscillation signifies involvement of the action-perception cycle, and both measures objectively indicate functional neuroplasticity in auditory perceptual learning.SIGNIFICANCE STATEMENT While suppression of auditory responses to self-generated sounds is well known, it is not clear whether the learned action-sound association modifies subsequent perception. Our study demonstrated the immediate effects of sound-making experience on perception using magnetoencephalographic recordings, as reflected in the increased auditory evoked P2 wave, increased responsiveness of β oscillations, and enhanced connectivity between auditory and sensorimotor cortices. The importance of motor learning was underscored as the changes were much smaller in a control group using a key press to generate the sounds instead of learning to play the musical instrument. The results support the rapid integration of a feedforward model during perception and provide a neurophysiological basis for the application of music making in motor rehabilitation training.

Phoneme processing skills are reflected in children's MMN responses

Phonological awareness (PA), the core contributor in phoneme processing abilities, has a link to later reading skills in children. However, the associations between PA and neural auditory discrimination are not clear. We used event-related potential (ERP) methodology and neuropsychological testing to monitor the neurocognitive basis of phonological awareness in typically developing children. We measured 5-6-year-old children's (N=70) phoneme processing, word completion and perceptual reasoning skills and compared their test results to their brain responses to phonemic changes, separately for each test. We found that children performing better in Phoneme processing test showed larger mismatch negativity (MMN) responses than children scoring lower in the same test. In contrast, no correspondence between test scores and brain responses was found for Auditory closure. Thus, the results suggest that automatic auditory change detection is linked to phoneme awareness in preschool children.

Recovery function of somatosensory evoked brain response in patients with carpal tunnel syndrome: A magnetoencephalographic study

OBJECTIVE

The recovery function of somatosensory evoked magnetic fields (SEFs) was recorded to investigate excitatory and inhibitory balance in the somatosensory cortex of patients with carpal tunnel syndrome.

METHODS

SEFs were recorded in patients and controls. Recordings were taken following median nerve stimulation with single and double pulses with interstimulus intervals of 10-200ms. The root mean square for the N20m component following the second stimulation was analyzed. SEFs following stimulation of the first and middle digits were also recorded and the location for the equivalent current dipoles was estimated in three-dimensional planes.

RESULTS

Distances on the vertical axis between the equivalent current dipoles for the first and third digits were shorter in patients than in control participants. The root mean square for the N20m recovered earlier in patients compared to controls; this was statistically significant at an interstimulus interval of 10ms. There was no relationship between N20m recovery and the equivalent current dipole location in the primary somatosensory cortex.

CONCLUSIONS

Carpal tunnel syndrome was associated with functional disinhibition and destruction of the somatotopic organization in the primary somatosensory cortex.

SIGNIFICANCE

Disinhibitory changes might induce a maladaptation of the central nervous system relating to pain.

Long-term influence of recurrent acute otitis media on neural involuntary attention switching in 2-year-old children

BACKGROUND

A large group of young children are exposed to repetitive middle ear infections but the effects of the fluctuating hearing sensations on immature central auditory system are not fully understood. The present study investigated the consequences of early childhood recurrent acute otitis media (RAOM) on involuntary auditory attention switching.

METHODS

By utilizing auditory event-related potentials, neural mechanisms of involuntary attention were studied in 22-26 month-old children (N = 18) who had had an early childhood RAOM and healthy controls (N = 19). The earlier and later phase of the P3a (eP3a and lP3a) and the late negativity (LN) were measured for embedded novel sounds in the passive multi-feature paradigm with repeating standard and deviant syllable stimuli. The children with RAOM had tympanostomy tubes inserted and all the children in both study groups had to have clinically healthy ears at the time of the measurement assessed by an otolaryngologist.

RESULTS

The results showed that lP3a amplitude diminished less from frontal to central and parietal areas in the children with RAOM than the controls. This might reflect an immature control of involuntary attention switch. Furthermore, the LN latency was longer in children with RAOM than in the controls, which suggests delayed reorientation of attention in RAOM.

CONCLUSIONS

The lP3a and LN responses are affected in toddlers who have had a RAOM even when their ears are healthy. This suggests detrimental long-term effects of RAOM on the neural mechanisms of involuntary attention.

Role of the thalamus in natural recovery of cognitive impairment in patients with mild traumatic brain injury

INTRODUCTION

Patients with mild traumatic brain injury (mTBI) may have normal neuroimaging but manifest with a broad-spectrum of cognitive-deficits, which may resolve eventually. The function of the thalamus in the process of natural-recovery remains elusive. The current study investigates the role of the thalamus in natural-recovery of cognitive-deficits in patients with mTBI.

METHODS

Twenty-one patients with mTBI were evaluated with an initial MRI scan, within 36 hours of injury and assessed with neuropsychological tests(NPT) at 3-4 weeks after injury. First and second follow-up MRI and NPT were performed at 3-4 months and 6-7 months, respectively. The volume and tensor measures of the thalamus and cognitive-scores were analysed at each assessment using repeated-measures of variance. The association of cognitive-scores with corresponding period imaging measures was analysed using bivariate-correlation.

RESULTS

Serial evaluation showed that all the cognitive-domains improved significantly. During this period there was a significant increase in mean thalamic volume (p = 0.049, effect-size = 0.18). After 3-4 months there was emergence of anisotropic thalamo-cortical connections. At 2-3 weeks and 6-7 months after injury, the alterations in diffusivity values were positively associated with improvement in memory-scores. Improvement in attention-scores correlated significantly with changes in tensor values at the 6-7 months after-injury.

CONCLUSION

The correlation between improvement in cognitive-scores and changes in thalamic tensor and volume measures reflect the role of the thalamus in natural-recovery after mTBI.

Effectiveness of music therapy as an aid to neurorestoration of children with severe neurological disorders

This study was a two-armed parallel group design aimed at testing real world effectiveness of a music therapy (MT) intervention for children with severe neurological disorders. The control group received only the standard neurorestoration program and the experimental group received an additional MT "Auditory Attention plus Communication protocol" just before the usual occupational and speech therapy. Multivariate Item Response Theory (MIRT) identified a neuropsychological status-latent variable manifested in all children and which exhibited highly significant changes only in the experimental group. Changes in brain plasticity also occurred in the experimental group, as evidenced using a Mismatch Event Related paradigm which revealed significant post intervention positive responses in the latency range between 308 and 400 ms in frontal regions. LORETA EEG source analysis identified prefrontal and midcingulate regions as differentially activated by the MT in the experimental group. Taken together, our results showing improved attention and communication as well as changes in brain plasticity in children with severe neurological impairments, confirm the importance of MT for the rehabilitation of patients across a wide range of dysfunctions.

Implicit learning of predictable sound sequences modulates human brain responses at different levels of the auditory hierarchy

Deviant stimuli, violating regularities in a sensory environment, elicit the mismatch negativity (MMN), largely described in the Event-Related Potential literature. While it is widely accepted that the MMN reflects more than basic change detection, a comprehensive description of mental processes modulating this response is still lacking. Within the framework of predictive coding, deviance processing is part of an inference process where prediction errors (the mismatch between incoming sensations and predictions established through experience) are minimized. In this view, the MMN is a measure of prediction error, which yields specific expectations regarding its modulations by various experimental factors. In particular, it predicts that the MMN should decrease as the occurrence of a deviance becomes more predictable. We conducted a passive oddball EEG study and manipulated the predictability of sound sequences by means of different temporal structures. Importantly, our design allows comparing mismatch responses elicited by predictable and unpredictable violations of a simple repetition rule and therefore departs from previous studies that investigate violations of different time-scale regularities. We observed a decrease of the MMN with predictability and interestingly, a similar effect at earlier latencies, within 70 ms after deviance onset. Following these pre-attentive responses, a reduced P3a was measured in the case of predictable deviants. We conclude that early and late deviance responses reflect prediction errors, triggering belief updating within the auditory hierarchy. Beside, in this passive study, such perceptual inference appears to be modulated by higher-level implicit learning of sequence statistical structures. Our findings argue for a hierarchical model of auditory processing where predictive coding enables implicit extraction of environmental regularities.

Auditory Perceptual Category Formation Does Not Require Perceptual Warping

Categorical perception occurs when a perceiver's stimulus classifications affect their ability to make fine perceptual discriminations and is the most intensively studied form of category learning. On the basis of categorical perception studies, it has been proposed that category learning proceeds by the deformation of an initially homogeneous perceptual space (“perceptual warping”), so that stimuli within the same category are perceived as more similar to each other (more difficult to tell apart) than stimuli that are the same physical distance apart but that belong to different categories. Here, we present a significant counterexample in which robust category learning occurs without these differential perceptual space deformations. Two artificial categories were defined along the dimension of pitch for a perceptually unfamiliar, multidimensional class of sounds. A group of participants (selected on the basis of their listening abilities) were trained to sort sounds into these two arbitrary categories. Category formation, verified empirically, was accompanied by a heightened sensitivity along the entire pitch range, as indicated by changes in an EEG index of implicit perceptual distance (mismatch negativity), with no significant resemblance to the local perceptual deformations predicted by categorical perception. This demonstrates that robust categories can be initially formed within a continuous perceptual dimension without perceptual warping. We suggest that perceptual category formation is a flexible, multistage process sequentially combining different types of learning mechanisms rather than a single process with a universal set of behavioral and neural correlates.

Mismatch negativity, social cognition, and functional outcomes in patients after traumatic brain injury

Mismatch negativity is generated automatically, and is an early monitoring indicator of neuronal integrity impairment and functional abnormality in patients with brain injury, leading to decline of cognitive function. Antipsychotic medication cannot affect mismatch negativity. The present study aimed to explore the relationships of mismatch negativity with neurocognition, daily life and social functional outcomes in patients after brain injury. Twelve patients with traumatic brain injury and 12 healthy controls were recruited in this study. We examined neurocognition with the Wechsler Adult Intelligence Scale-Revised China, and daily and social functional outcomes with the Activity of Daily Living Scale and Social Disability Screening Schedule, respectively. Mismatch negativity was analyzed from electroencephalogram recording. The results showed that mismatch negativity amplitudes decreased in patients with traumatic brain injury compared with healthy controls. Mismatch negativity amplitude was negatively correlated with measurements of neurocognition and positively correlated with functional outcomes in patients after traumatic brain injury. Further, the most significant positive correlations were found between mismatch negativity in the fronto-central region and measures of functional outcomes. The most significant positive correlations were also found between mismatch negativity at the FCz electrode and daily living function. Mismatch negativity amplitudes were extremely positively associated with Social Disability Screening Schedule scores at the Fz electrode in brain injury patients. These experimental findings suggest that mismatch negativity might efficiently reflect functional outcomes in patients after traumatic brain injury.

Modulation of pre-attentive spectro-temporal feature processing in the human auditory system by HD-tDCS

The present study examined the functional lateralization of the human auditory cortex (AC) for pre-attentive spectro-temporal feature processing. By using high-definition transcranial direct current stimulation (HD-tDCS), we systematically modulated neuronal activity of the bilateral AC. We assessed the influence of anodal and cathodal HD-tDCS delivered over the left or right AC on auditory mismatch negativity (MMN) in response to temporal as well as spectral deviants in 12 healthy subjects. The results showed that MMN to temporal deviants was significantly enhanced by anodal HD-tDCS applied over the left AC only. Our data indicate a left hemispheric dominance for the pre-attentive processing of low-level temporal information.

Neuroscience illuminating the influence of auditory or phonological intervention on language-related deficits

Remediation programs for language-related learning deficits are urgently needed to enable equal opportunities in education. To meet this need, different training and intervention programs have been developed. Here we review, from an educational perspective, studies that have explored the neural basis of behavioral changes induced by auditory or phonological training in dyslexia, specific language impairment (SLI), and language-learning impairment (LLI). Training has been shown to induce plastic changes in deficient neural networks. In dyslexia, these include, most consistently, increased or normalized activation of previously hypoactive inferior frontal and occipito-temporal areas. In SLI and LLI, studies have shown the strengthening of previously weak auditory brain responses as a result of training. The combination of behavioral and brain measures of remedial gains has potential to increase the understanding of the causes of language-related deficits, which may help to target remedial interventions more accurately to the core problem.

Are scalar implicatures automatically processed and different for each individual? A mismatch negativity (MMN) study

Scalar implicatures are ordinarily activated in human communication when the speaker uses a weak expression (e.g., some) from a set of stronger alternatives (e.g., many, all). It has been debated whether scalar inferences are generated by default. To clarify this issue and examine whether individual pragmatic ability will affect the mechanism of scalar inference processing, we performed experiment with an MMN paradigm to capture the neurophysiological indicators of automatic processing of spoken sentences and divided participants into high and low pragmatic ability groups. Experimental results showed that compared with the condition that an informative sentence ("Some animals have tails") is the deviant stimuli, when an underinformative sentence ("Some tigers have tails") is the deviant stimuli, the high pragmatic ability group induced mismatch negativity (MMN) and sustained negativity, while the low pragmatic ability group had no ERP effects. These results indicated that at least some people can automatically activate the scalar implicatures when encountering scalar trigger words, even in the inattentive status.

Visual mismatch negativity: a predictive coding view

An increasing number of studies investigate the visual mismatch negativity (vMMN) or use the vMMN as a tool to probe various aspects of human cognition. This paper reviews the theoretical underpinnings of vMMN in the light of methodological considerations and provides recommendations for measuring and interpreting the vMMN. The following key issues are discussed from the experimentalist's point of view in a predictive coding framework: (1) experimental protocols and procedures to control "refractoriness" effects; (2) methods to control attention; (3) vMMN and veridical perception.

Atypical central auditory speech-sound discrimination in children who stutter as indexed by the mismatch negativity

PURPOSE

Recent theoretical conceptualizations suggest that disfluencies in stuttering may arise from several factors, one of them being atypical auditory processing. The main purpose of the present study was to investigate whether speech sound encoding and central auditory discrimination, are affected in children who stutter (CWS).

METHODS

Participants were 10 CWS, and 12 typically developing children with fluent speech (TDC). Event-related potentials (ERPs) for syllables and syllable changes [consonant, vowel, vowel-duration, frequency (F0), and intensity changes], critical in speech perception and language development of CWS were compared to those of TDC.

RESULTS

There were no significant group differences in the amplitudes or latencies of the P1 or N2 responses elicited by the standard stimuli. However, the Mismatch Negativity (MMN) amplitude was significantly smaller in CWS than in TDC. For TDC all deviants of the linguistic multifeature paradigm elicited significant MMN amplitudes, comparable with the results found earlier with the same paradigm in 6-year-old children. In contrast, only the duration change elicited a significant MMN in CWS.

CONCLUSIONS

The results showed that central auditory speech-sound processing was typical at the level of sound encoding in CWS. In contrast, central speech-sound discrimination, as indexed by the MMN for multiple sound features (both phonetic and prosodic), was atypical in the group of CWS. Findings were linked to existing conceptualizations on stuttering etiology.

EDUCATIONAL OBJECTIVES

The reader will be able (a) to describe recent findings on central auditory speech-sound processing in individuals who stutter, (b) to describe the measurement of auditory reception and central auditory speech-sound discrimination, (c) to describe the findings of central auditory speech-sound discrimination, as indexed by the mismatch negativity (MMN), in children who stutter.

The neural basis of sublexical speech and corresponding nonspeech processing: a combined EEG-MEG study

We addressed the neural organization of speech versus nonspeech sound processing by investigating preattentive cortical auditory processing of changes in five features of a consonant-vowel syllable (consonant, vowel, sound duration, frequency, and intensity) and their acoustically matched nonspeech counterparts in a simultaneous EEG-MEG recording of mismatch negativity (MMN/MMNm). Overall, speech-sound processing was enhanced compared to nonspeech sound processing. This effect was strongest for changes which affect word meaning (consonant, vowel, and vowel duration) in the left and for the vowel identity change in the right hemisphere also. Furthermore, in the right hemisphere, speech-sound frequency and intensity changes were processed faster than their nonspeech counterparts, and there was a trend for speech-enhancement in frequency processing. In summary, the results support the proposed existence of long-term memory traces for speech sounds in the auditory cortices, and indicate at least partly distinct neural substrates for speech and nonspeech sound processing.

Prenatal music exposure induces long-term neural effects

We investigated the neural correlates induced by prenatal exposure to melodies using brains' event-related potentials (ERPs). During the last trimester of pregnancy, the mothers in the learning group played the ‘Twinkle twinkle little star’ -melody 5 times per week. After birth and again at the age of 4 months, we played the infants a modified melody in which some of the notes were changed while ERPs to unchanged and changed notes were recorded. The ERPs were also recorded from a control group, who received no prenatal stimulation. Both at birth and at the age of 4 months, infants in the learning group had stronger ERPs to the unchanged notes than the control group. Furthermore, the ERP amplitudes to the changed and unchanged notes at birth were correlated with the amount of prenatal exposure. Our results show that extensive prenatal exposure to a melody induces neural representations that last for several months.