Infancy and early childhood maturation of neural auditory change detection and its associations to familial dyslexia risk.

OBJECTIVE: We investigated early maturation of the infant mismatch response MMR, including mismatch negativity (MMN), positive MMR (P-MMR), and late discriminative negativity (LDN), indexing auditory discrimination abilities, and the influence of familial developmental dyslexia risk. METHODS: We recorded MMRs to vowel, duration, and frequency deviants in pseudo-words at 0, 6, and 28 months and compared MMRs in subgroups with vs. without dyslexia risk, in a sample over-represented by risk infants. RESULTS: Neonatal MMN to the duration deviant became larger and earlier by 28 months; MMN was elicited by more deviants only at 28 months. The P-MMR was predominant in infancy; its amplitude increased by 6 and decreased by 28 months; latency decreased with increasing age. An LDN emerged by 6 months and became larger and later by 28 months. Dyslexia risk affected MMRs and their maturation. CONCLUSIONS: MMRs demonstrate an expected maturational pattern with 2-3 peaks by 28 months. The effects of dyslexia risk are prominent but not always as expected. SIGNIFICANCE: This large-scale longitudinal study shows MMR maturation with three age groups and three deviants. Results illuminate MMR's relation to the adult responses, and hence their cognitive underpinnings, and help in identifying typical/atypical auditory development in early childhood.

Atypical beta power fluctuation while listening to an isochronous sequence in dyslexia.

OBJECTIVE: Developmental dyslexia is a reading disorder that features difficulties in perceiving and tracking rhythmic regularities in auditory streams, such as speech and music. Studies on typical healthy participants have shown that power fluctuations of neural oscillations in beta band (15-25 Hz) reflect an essential mechanism for tracking rhythm or entrainment and relate to predictive timing and attentional processes. Here we investigated whether adults with dyslexia have atypical beta power fluctuation. METHODS: The electroencephalographic activities of individuals with dyslexia (n = 13) and typical control participants (n = 13) were measured while they passively listened to an isochronous tone sequence (2 Hz presentation rate). The time-frequency neural activities generated from auditory cortices were analyzed. RESULTS: The phase of beta power fluctuation at the 2 Hz stimulus presentation rate differed and appeared opposite between individuals with dyslexia and controls. CONCLUSIONS: Atypical beta power fluctuation might reflect deficits in perceiving and tracking auditory rhythm in dyslexia. SIGNIFICANCE: These findings extend our understanding of atypical neural activities for tracking rhythm in dyslexia and could inspire novel methods to objectively measure the benefits of training, and predict potential benefit of auditory rhythmic rehabilitation programs on an individual basis.

Transcranial electrical stimulation improves phoneme processing in developmental dyslexia.

BACKGROUND: About 10% of the western population suffers from a specific disability in the acquisition of reading and writing skills, known as developmental dyslexia (DD). Even though DD starts in childhood it frequently continuous throughout lifetime. Impaired processing of acoustic features at the phonematic scale based on dysfunctional auditory temporal resolution is considered as one core deficit underlying DD. Recently, the efficacy of transcranial electrical stimulation (tES) to modulate auditory temporal resolution and phoneme processing in healthy individuals has been demonstrated. OBJECTIVE: The present work aims to investigate online effects of tES on phoneme processing in individuals with DD. METHOD: Using an established phoneme-categorization task, we assessed the immediate behavioral and electrophysiological effects of transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) over bilateral auditory cortex in children and adolescents with DD (study 1) and adults with DD (study 2) on auditory phoneme processing acuity. RESULTS: Our data revealed that tACS improved phoneme categorization in children and adolescents with DD, an effect that was paralleled by an increase in evoked brain response patterns representing low-level sensory processing. In the adult sample we replicated these findings and additionally showed a more pronounced impact of tRNS on phoneme-categorization acuity. CONCLUSION: These results provide compelling evidence for the potential of both tACS and tRNS to increase temporal precision of the auditory system in DD and suggest transcranial electrical stimulation as potential intervention in DD to foster the effect of standard phonology-based training.

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

OBJECTIVE: Identifying 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. METHODS: ERPs 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. RESULTS: An 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. CONCLUSIONS: The MMRs of high-risk infants were absent or diminished, and morphologically atypical, suggesting atypical neural speech-sound discrimination. SIGNIFICANCE: This atypical neural basis for speech discrimination may contribute to impaired language development, potentially leading to future reading problems.

Spatial selective attention and asynchrony of cognitive systems in adult dyslexic readers: an ERPs and behavioral study.

The aim of this study was to gain additional knowledge about the asynchrony phenomenon in developmental dyslexia, especially when spatial selective attention is manipulated. Adults with developmental dyslexia and non-impaired readers underwent two experimental tasks, one including alphabetic stimuli (pre-lexical consonant-vowel syllables) and the other containing non-alphabetic stimuli (pictures and sounds of animals). Participants were instructed to attend to the right or left hemifields and to respond to all stimuli on that hemifield. Behavioral parameters and event-related potentials were recorded. The main finding was that the dyslexic readers demonstrated asynchrony between the auditory and visual modalities when alphabetic stimuli were presented on the right hemifield. These results suggest that intact reading is linked to a synchronized auditory and visual speed of processing even when spatial selective attention is manipulated. The findings of the current study are discussed in terms of asynchrony between modalities as a neurocognitive marker in developmental dyslexia.

Reading comprehension difficulties in children with rolandic epilepsy.

AIM: Difficulties in reading comprehension can arise from either word reading or listening comprehension difficulties, or a combination of the two. We sought to determine whether children with rolandic epilepsy had poor reading comprehension relative to typically developing comparison children, and whether such difficulties were associated with word reading and/or general language comprehension difficulties. METHOD: In this cross-sectional study, children with rolandic epilepsy (n=25; 16 males, 9 females; mean age 9y 1mo, SD 1y 7mo) and a comparison group (n=39; 25 males, 14 females; mean age 9y 1mo, SD 1y 3mo) completed assessments of reading comprehension, listening comprehension, word/non-word reading, speech articulation, and Non-verbal IQ. RESULTS: Reading comprehension and word reading were worse in children with rolandic epilepsy (F1,61 =6.89, p=0.011, ηp2=0.10 and F1,61 =6.84, p=0.011, ηp2=0.10 respectively), with listening comprehension being marginal (F1,61 =3.81, p=0.055, ηp2=0.06). Word reading and listening comprehension made large and independent contributions to reading comprehension, explaining 70% of the variance. INTERPRETATION: Children with rolandic epilepsy may be at risk of reading comprehension difficulties. Thorough assessment of individual children is required to ascertain whether the difficulties lie with decoding text, or with general comprehension skills, or both. WHAT THIS PAPER ADDS: Children with rolandic epilepsy may be at risk of poor reading comprehension. This was related to poor word reading, poor listening comprehension, or both. Reading comprehension interventions should be tailored to the profile of difficulties.

Cortical responses to tone and phoneme mismatch as a predictor of dyslexia? A systematic review.

Evidence from event-related-potential (ERP) studies has repeatedly shown differences in the perception and processing of auditory stimuli in children with dyslexia compared to control children. The mismatch negativity (MMN) - an ERP component reflecting passive auditory change detection ability - has been found to be reduced, not only in children with a diagnosis of dyslexia, but also in infants and preschool children at risk of developing dyslexia. However, the results are controversial due to the different methods, age of the children and stimuli used. The aim of the present review is to summarize and evaluate the MMN research about at-risk children in order to identify risk factors that discriminate between children with and without dyslexia risk and to analyze if the MMR (the abbreviation refers to positive and negative mismatch responses) correlates with later reading and spelling ability. A literature search yielded 17 studies reporting MMR to speech or non-speech stimuli in children at risk of dyslexia. The results of the studies were inconsistent. Studies measuring speech MMR often found attenuated amplitudes in the at-risk group, but mainly in very young children. The results for older children (6-7years) and for non-speech stimuli are more heterogeneous. A moderate positive correlation of MMR amplitude size with later reading and spelling abilities was consistently found. Overall, the findings of this review indicate that the MMR can be a valuable part of early dyslexia identification, which can enable efficient support and intervention for a child before the first problems appear.

The role of feedback in implicit and explicit artificial grammar learning: a comparison between dyslexic and non-dyslexic adults.

The importance of feedback for learning has been firmly established over the past few decades. The question of whether feedback plays a significant role in the statistical learning abilities of adults with dyslexia, however, is currently unresolved. Here, we examined the role of feedback in grammaticality judgment, type of structural knowledge, and confidence rating in both typically developed and dyslexic adults. We implemented two artificial grammar learning experiments: implicit and explicit. The second experiment was directly analogous to the first experiment in all respects except training format: the standard memorization instruction was replaced with an explicit rule-search instruction. Each experiment was conducted with and without performance feedback. While both groups showed significantly improved learning in the feedback-based explicit artificial grammar learning task, only the typically developed adults demonstrated higher levels of conscious structural knowledge. The present study demonstrates that the basis for the grammaticality judgment of adults with dyslexia differs from that of typically developed adults, regardless of increase in the level of explicitness.

Dyslexia in general practice education: considerations for recognition and support.

Dyslexia is a common developmental learning difficulty, which persists throughout life. It is highly likely that those working in primary care will know, or even work with someone who has dyslexia. Dyslexia can impact on performance in postgraduate training and exams. The stereotypical characteristics of dyslexia, such as literacy difficulties, are often not obvious in adult learners. Instead, recognition requires a holistic approach to evaluating personal strengths and difficulties, in the context of a supportive relationship. Strategies to support dyslexic learners should consider recommendations made in formal diagnostic reports, and aim to address self-awareness and coping skills.

Letter-sound processing deficits in children with developmental dyslexia: An ERP study.

OBJECTIVE: The time course during letter-sound processing was investigated in children with developmental dyslexia (DD) and typically developing (TD) children using electroencephalography. METHOD: Thirty-eight children with DD and 25 TD children participated in a visual-auditory oddball paradigm. Event-related potentials (ERPs) elicited by standard and deviant stimuli in an early (100-190 ms) and late (560-750 ms) time window were analysed. RESULTS: In the early time window, ERPs elicited by the deviant stimulus were delayed and less left lateralized over fronto-temporal electrodes for children with DD compared to TD children. In the late time window, children with DD showed higher amplitudes extending more over right frontal electrodes. Longer latencies in the early time window and stronger right hemispheric activation in the late time window were associated with slower reading and naming speed. Additionally, stronger right hemispheric activation in the late time window correlated with poorer phonological awareness skills. CONCLUSIONS: Deficits in early stages of letter-sound processing influence later more explicit cognitive processes during letter-sound processing. SIGNIFICANCE: Identifying the neurophysiological correlates of letter-sound processing and their relation to reading related skills provides insight into the degree of automaticity during letter-sound processing beyond behavioural measures of letter-sound-knowledge.

Neural processing of amplitude and formant rise time in dyslexia.

This study aimed to investigate how children with dyslexia weight amplitude rise time (ART) and formant rise time (FRT) cues in phonetic discrimination. Passive mismatch responses (MMR) were recorded for a/ba/-/wa/contrast in a multiple deviant odd-ball paradigm to identify the neural response to cue weighting in 17 children with dyslexia and 17 age-matched control children. The deviant stimuli had either partial or full ART or FRT cues. The results showed that ART did not generate an MMR in either group, whereas both partial and full FRT cues generated MMR in control children while only full FRT cues generated MMR in children with dyslexia. These findings suggest that children, both controls and those with dyslexia, discriminate speech based on FRT cues and not ART cues. However, control children have greater sensitivity to FRT cues in speech compared to children with dyslexia.

Neurociencia y Educación: ¿podemos ir de la investigación básica a su aplicación? Un posible marco de referencia desde la investigación en dislexia1 / Neurociencia y Educación: ¿podemos ir de la investigación básica a su aplicación? Un posible marco de referencia desde la investigación en dislexia

La neurociencia podría transformar la educación, pues proporciona nuevos métodos para comprender el aprendizaje y el desarrollo cognitivo, sus mecanismos causales y una forma empírica de evaluar la eficacia de diferentes pedagogías. No obstante, éste sería un objetivo a largo plazo. Desde la neurociencia educativa se debería empezar estudiando cómo los sistemas cognitivos se construyen sobre los sensoriales a lo largo del desarrollo. Aquí me centraré en el lenguaje. Pequeñas diferencias individuales iniciales en una función sensorial, por ejemplo la auditiva, podrían ser el origen de notables diferencias individuales en el desarrollo lingüístico. La neurociencia podría proporcionar una comprensión detallada de los mecanismos causales del desarrollo que vinculan la audición, el desarrollo fonológico y el desarrollo de la alfabetización. Este tipo de investigación neurocientífica básica podría orientar al campo de la educación y la pedagogía explorando los efectos que sobre estos mecanismos ejercen diferentes contextos pedagógicos y de aprendizaje

Neuroscience has the potential to transform education because it provides novel methods for understanding human learning and cognitive development. It therefore offers deeper understanding of causal mechanisms in learning and an empirical approach to evaluating the efficacy of different pedagogies. However, this will be a long-term enterprise and there will be few immediate pay-offs. Here I set out one possible framework for linking basic research in neuroscience to pedagogical questions in education. I suggest that the developing field of educational neuroscience must first study how sensory systems build cognitive systems over developmental time. I focus on one cognitive system, language, the efficient functioning of which is critical for reading acquisition. Small initial differences in sensory function, for example auditory function, have the potential to cause large differences in linguistic performance over the learning trajectory. The tools offered by neuroscience can enable better understanding of the causal developmental mechanisms linking audition, phonological development and literacy development, in fine-grained detail. Following this basic research, neuroscience can then inform education and pedagogy by exploring the effects on these neural mechanisms of different learning contexts and pedagogies

Incidental learning of sound categories is impaired in developmental dyslexia.

Developmental dyslexia is commonly thought to arise from specific phonological impairments. However, recent evidence is consistent with the possibility that phonological impairments arise as symptoms of an underlying dysfunction of procedural learning. The nature of the link between impaired procedural learning and phonological dysfunction is unresolved. Motivated by the observation that speech processing involves the acquisition of procedural category knowledge, the present study investigates the possibility that procedural learning impairment may affect phonological processing by interfering with the typical course of phonetic category learning. The present study tests this hypothesis while controlling for linguistic experience and possible speech-specific deficits by comparing auditory category learning across artificial, nonlinguistic sounds among dyslexic adults and matched controls in a specialized first-person shooter videogame that has been shown to engage procedural learning. Nonspeech auditory category learning was assessed online via within-game measures and also with a post-training task involving overt categorization of familiar and novel sound exemplars. Each measure reveals that dyslexic participants do not acquire procedural category knowledge as effectively as age- and cognitive-ability matched controls. This difference cannot be explained by differences in perceptual acuity for the sounds. Moreover, poor nonspeech category learning is associated with slower phonological processing. Whereas phonological processing impairments have been emphasized as the cause of dyslexia, the current results suggest that impaired auditory category learning, general in nature and not specific to speech signals, could contribute to phonological deficits in dyslexia with subsequent negative effects on language acquisition and reading. Implications for the neuro-cognitive mechanisms of developmental dyslexia are discussed.

Informational masking of speech in dyslexic children.

Studies evaluating speech perception in noise have reported inconsistent results regarding a potential deficit in dyslexic children. So far, most of them investigated energetic masking. The present study evaluated situations inducing mostly informational masking, which reflects cognitive interference induced by the masker. Dyslexic children were asked to identify a female target syllable presented in quiet, babble, unmodulated, and modulated speech-shaped noise. Whereas their performance was comparable to normal-reading children in quiet, it dropped significantly in all noisy conditions compared to age-, but not reading level-matched controls. Interestingly, noise affected similarly the reception of voicing, place, and manner of articulation in dyslexic and normal-reading children.

Basic auditory processing is related to familial risk, not to reading fluency: an ERP study.

Less proficient basic auditory processing has been previously connected to dyslexia. However, it is unclear whether a low proficiency level is a correlate of having a familial risk for reading problems, or whether it causes dyslexia. In this study, children's processing of amplitude rise time (ART), intensity and frequency differences was measured with event-related potentials (ERPs). ERP components of interest are components reflective of auditory change detection; the mismatch negativity (MMN) and late discriminative negativity (LDN). All groups had an MMN to changes in ART and frequency, but not to intensity. Our results indicate that fluent readers at risk for dyslexia, poor readers at risk for dyslexia and fluent reading controls have an LDN to changes in ART and frequency, though the scalp activation of frequency processing was different for familial risk children. On intensity, only controls showed an LDN. Contrary to previous findings, our results suggest that neither ART nor frequency processing is related to reading fluency. Furthermore, our results imply that diminished sensitivity to changes in intensity and differential lateralization of frequency processing should be regarded as correlates of being at familial risk for dyslexia, that do not directly relate to reading fluency.

Enhancement of brain event-related potentials to speech sounds is associated with compensated reading skills in dyslexic children with familial risk for dyslexia.

Specific reading disability, dyslexia, is a prevalent and heritable disorder impairing reading acquisition characterized by a phonological deficit. However, the underlying mechanism of how the impaired phonological processing mediates resulting dyslexia or reading disabilities remains still unclear. Using ERPs we studied speech sound processing of 30 dyslexic children with familial risk for dyslexia, 51 typically reading children with familial risk for dyslexia, and 58 typically reading control children. We found enhanced brain responses to shortening of a phonemic length in pseudo-words (/at:a/ vs. /ata/) in dyslexic children with familial risk as compared to other groups. The enhanced brain responses were associated with better performance in behavioral phonemic length discrimination task, as well as with better reading and writing accuracy. Source analyses revealed that the brain responses of sub-group of dyslexic children with largest responses originated from a more posterior area of the right temporal cortex as compared to the responses of the other participants. This is the first electrophysiological evidence for a possible compensatory speech perception mechanism in dyslexia. The best readers within the dyslexic group have probably developed alternative strategies which employ compensatory mechanisms substituting their possible earlier deficit in phonological processing and might therefore be able to perform better in phonemic length discrimination and reading and writing accuracy tasks. However, we speculate that for reading fluency compensatory mechanisms are not that easily built and dyslexic children remain slow readers during their adult life.

The role of the efferent auditory system in developmental dyslexia.

OBJECTIVE: To assess the role of the efferent auditory system by inhibition of contralateral otoacoustic emission in dyslexic children with auditory processing disorders. METHODS: The study sample was 34 children: 17 with dyslexia and 17 age-matched controls. Sensitive speech tests (low-pass filtered, time-compressed, distorted and dichotic) were performed to assess coexisting auditory processing disorder. Distortion-product otoacoustic emission (DPOAE) values were measured in basal condition and with contralateral broadband noise signal delivered via an earphone transducer at 60 dB SPL. RESULTS: The lower scores at sensitive speech testing confirmed the association of an auditory processing disorder in the dyslexic children. DPOAE values were significantly attenuated by contralateral inhibition only in the control group (p=0.001; dyslexics, p=0.19); attenuation was not significant at any frequency in the dyslexic group. CONCLUSIONS: The differences in DPOAE attenuation between the groups, although not statistically significant, suggest alterations in the auditory efferent system in the dyslexic population. These alterations may affect language perception. If confirmed in further studies with larger samples, these results could provide insight into a possible pathophysiological background of dyslexia.

Reading in subjects with an oral cleft: speech, hearing and neuropsychological skills.

OBJECTIVE: To evaluate speech, hearing, and neuropsychological correlates to reading among children, adolescents, and young adults with nonsyndromic cleft of the lip and/or palate (NSCL/P). METHOD: All testing was completed in a single visit at a Midwestern university hospital. Subjects in both the NSCL/P (n = 80) and the control groups (n = 62) ranged in age from 7-26 years (average age = 17.60 and 17.66, respectively). Subjects completed a battery of standardized tests evaluating intelligence, neuropsychological skills, and word reading. Subjects with NSCL/P also underwent speech assessment, and past audiology records were evaluated. RESULTS: After controlling for age and socioeconomic status, subjects with cleft performed significantly worse on a test of word reading. For subjects with cleft, word reading deficits were not associated with measures of speech or hearing, but were correlated with impairments in auditory memory. CONCLUSION: These findings show poorer reading among subjects with NSCL/P compared with those without. Further work needs to focus on correlates of reading among subjects with cleft to allow early identification and appropriate intervention/accommodation for those at risk.

Perceptual learning of acoustic noise by individuals with dyslexia.

PURPOSE: A phonological deficit is thought to affect most individuals with developmental dyslexia. The present study addresses whether the phonological deficit is caused by difficulties with perceptual learning of fine acoustic details. METHOD: A demanding test of nonverbal auditory memory, "noise learning," was administered to both adults with dyslexia and control adult participants. On each trial, listeners had to decide whether a stimulus was a 1-s noise token or 2 abutting presentations of the same 0.5-s noise token (repeated noise). Without the listener's knowledge, the exact same noise tokens were presented over many trials. An improved ability to perform the task for such "reference" noises reflects learning of their acoustic details. RESULTS: Listeners with dyslexia did not differ from controls in any aspect of the task, qualitatively or quantitatively. They required the same amount of training to achieve discrimination of repeated from nonrepeated noises, and they learned the reference noises as often and as rapidly as the control group. However, they did show all the hallmarks of dyslexia, including a well-characterized phonological deficit. CONCLUSION: The data did not support the hypothesis that deficits in basic auditory processing or nonverbal learning and memory are the cause of the phonological deficit in dyslexia.