Age, dyslexia subtype and comorbidity modulate rapid auditory processing in developmental dyslexia

Sequence Processing in Music Predicts Reading Skills in Young Readers: A Longitudinal Study

Musical abilities, both in the pitch and temporal dimension, have been shown to be positively associated with phonological awareness and reading abilities in both children and adults. There is increasing evidence that the relationship between music and language relies primarily on the temporal dimension, including both meter and rhythm. It remains unclear to what extent skill level in these temporal aspects of music may uniquely contribute to the prediction of reading outcomes. A longitudinal design was used to test a group-administered musical sequence transcription task (MSTT). This task was designed to preferentially engage sequence processing skills while controlling for fine-grained pitch discrimination and rhythm in terms of temporal grouping. Forty-five children, native speakers of Portuguese (Mage = 7.4 years), completed the MSTT and a cognitive-linguistic protocol that included visual and auditory working memory tasks, as well as phonological awareness and reading tasks in second grade. Participants then completed reading assessments in third and fifth grades. Longitudinal regression models showed that MSTT and phonological awareness had comparable power to predict reading. The MSTT showed an overall classification accuracy for identifying low-achievement readers in Grades 2, 3, and 5 that was analogous to a comprehensive model including core predictors of reading disability. In addition, MSTT was the variable with the highest loading and the most discriminatory indicator of a phonological factor. These findings carry implications for the role of temporal sequence processing in contributing to the relationship between music and language and the potential use of MSTT as a language-independent, time- and cost-effective tool for the early identification of children at risk of reading disability.

Intact procedural memory and impaired auditory statistical learning in adults with dyslexia

Developmental dyslexia is a reading disorder that is associated with atypical brain function. One neuropsychological theory posits that dyslexia reflects a deficit in the procedural memory system, which supports implicit learning, or the acquisition of knowledge without conscious awareness or intention. This study investigated various forms of procedural learning in adults with dyslexia and typically-reading adults. Adults with dyslexia exhibited typical skill learning on mirror tracing and rotary pursuit tasks that have been well-established as reflecting purely procedural memory and dependent on basal ganglia and cerebellar structures. They also exhibited typical statistical learning for visual material, but impaired statistical learning for auditory material. Auditory statistical learning proficiency correlated positively with single-word reading performance across all participants and within the group with dyslexia, linking a major difficulty in dyslexia with impaired auditory statistical learning. These findings dissociate multiple forms of procedural memory that are intact in dyslexia from a specific impairment in auditory statistical learning that is associated with reading difficulty.

Dyslexia: Causes and Concomitant Impairments

In recent decades, theories have been presented to explain the nature of dyslexia, but the causes of dyslexia remained unclear. Although the investigation of the causes of dyslexia presupposes a clear understanding of the concept of cause, such an understanding is missing. The present paper proposes the absence of at least one necessary condition or the absence of all sufficient conditions as causes for impaired reading. The causes of impaired reading include: an incorrect fixation location, too short a fixation time, the attempt to recognize too many letters simultaneously, too large saccade amplitudes, and too short verbal reaction times. It is assumed that a longer required fixation time in dyslexic readers results from a functional impairment of areas V1, V2, and V3 that require more time to complete temporal summation. These areas and areas that receive input from them, such as the fusiform gyrus, are assumed to be impaired in their ability to simultaneously process a string of letters. When these impairments are compensated by a new reading strategy, reading ability improves immediately.

Speech-specific perceptual adaptation deficits in children and adults with dyslexia

According to several influential theoretical frameworks, phonological deficits in dyslexia result from reduced sensitivity to acoustic cues that are essential for the development of robust phonemic representations. Some accounts suggest that these deficits arise from impairments in rapid auditory adaptation processes that are either speech-specific or domain-general. Here, we examined the specificity of auditory adaptation deficits in dyslexia using a nonlinguistic tone anchoring (adaptation) task and a linguistic selective adaptation task in children and adults with and without dyslexia. Children and adults with dyslexia had elevated tone-frequency discrimination thresholds, but both groups benefited from anchoring to repeated stimuli to the same extent as typical readers. Additionally, although both dyslexia groups had overall reduced accuracy for speech sound identification, only the child group had reduced categorical perception for speech. Across both age groups, individuals with dyslexia had reduced perceptual adaptation to speech. These results highlight broad auditory perceptual deficits across development in individuals with dyslexia for both linguistic and nonlinguistic domains, but speech-specific adaptation deficits. Finally, mediation models in children and adults revealed that the causal pathways from basic perception and adaptation to phonological awareness through speech categorization were not significant. Thus, rather than having causal effects, perceptual deficits may co-occur with the phonological deficits in dyslexia across development. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Is Developmental Dyslexia Due to a Visual and Not a Phonological Impairment?

It is a widely held belief that developmental dyslexia (DD) is a phonological disorder in which readers have difficulty associating graphemes with their corresponding phonemes. In contrast, the magnocellular theory of dyslexia assumes that DD is a visual disorder caused by dysfunctional magnocellular neural pathways. The review explores arguments for and against these theories. Recent results have shown that DD is caused by (1) a reduced ability to simultaneously recognize sequences of letters that make up words, (2) longer fixation times required to simultaneously recognize strings of letters, and (3) amplitudes of saccades that do not match the number of simultaneously recognized letters. It was shown that pseudowords that could not be recognized simultaneously were recognized almost without errors when the fixation time was extended. However, there is an individual maximum number of letters that each reader with DD can recognize simultaneously. Findings on the neurobiological basis of temporal summation have shown that a necessary prolongation of fixation times is due to impaired processing mechanisms of the visual system, presumably involving magnocells and parvocells. An area in the mid-fusiform gyrus also appears to play a significant role in the ability to simultaneously recognize words and pseudowords. The results also contradict the assumption that DD is due to a lack of eye movement control. The present research does not support the assumption that DD is caused by a phonological disorder but shows that DD is due to a visual processing dysfunction.

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.

Unisensory and multisensory temporal processing in autism and dyslexia: A systematic review and meta-analysis

This study presents a comprehensive systematic review and meta-analysis of temporal processing in autism spectrum disorder (ASD) and developmental dyslexia (DD), two neurodevelopmental disorders in which temporal processing deficits have been highly researched. The results provide strong evidence for impairments in temporal processing in both ASD (g = 0.48) and DD (g = 0.82), as measured by judgments of temporal order and simultaneity. In individual analyses, multisensory temporal processing was impaired for both ASD and DD, and unisensory auditory, visual and tactile processing were all impaired in DD. In ASD, speech stimuli showed moderate impairment effect sizes, whereas nonspeech stimuli showed small effects. Greater reading and spelling skills in DD were associated with greater temporal precision. Temporal deficits did not show changes with age in either disorder. In addition to more clearly defining temporal impairments in ASD and DD, the results highlight common and distinct patterns of temporal processing between these disorders. Deficits are discussed in relation to existing theoretical models, and recommendations are made for future research.

The processing of rhythmic structures in music and prosody by children with developmental dyslexia and developmental language disorder

Rhythm perception seems to be crucial to language development. Many studies have shown that children with developmental dyslexia and developmental language disorder have difficulties in processing rhythmic structures. In this study, we investigated the relationships between prosody and musical processing in Italian children with typical and atypical development. The tasks aimed to reproduce linguistic prosodic structures through musical sequences, offering a direct comparison between the two domains without violating the specificities of each one. About 16 Typically Developing children, 16 children with a diagnosis of Developmental Dyslexia, and 16 with a diagnosis of developmental language disorder (age 10-13 years) participated in the experimental study. Three tasks were administered: an association task between a sentence and its humming version, a stress discrimination task (between couples of sounds reproducing the intonation of Italian trisyllabic words), and an association task between trisyllabic nonwords with different stress position and three-notes musical sequences with different musical stress. Children with developmental language disorder perform significantly lower than Typically Developing children on the humming test. By contrast, children with developmental dyslexia are significantly slower than TD in associating nonwords with musical sequences. Accuracy and speed in the experimental tests correlate with metaphonological, language, and word reading scores. Theoretical and clinical implications are discussed within a multidimensional model of neurodevelopmental disorders including prosodic and rhythmic skills at word and sentence level.

Pitch as the Main Determiner of Italian Lexical Stress Perception Across the Lifespan: Evidence From Typical Development and Dyslexia

The study deals with the issue of lexical stress perception in both a developmental (comparing children and adults with typical development) and a clinical perspective (comparing typically developing children and children with dyslexia). The three parameters characterizing the acoustic profiles of words and non-words in a certain language are duration, pitch and intensity of its syllables. Based on (sparse) previous literature on Italian and other European languages, it was expected that syllable duration would be the parameter predominantly determining the perception of stress position. It was furthermore anticipated that children with dyslexia may be found to have an altered perception of lexical stress, due to their impairments in auditory processing of either pitch, duration or (more controversial) intensity. Systematic manipulation of the pitch, duration and intensity profiles of three Italian trisyllabic non-words produced a series of 81 stimuli, that were judged with respect to stress position (perceived on the ultimate, penultimate, or antepenultimate syllable) by the three groups of participants. The results showed, contrarily to expectations, that the pitch component is the most reliable acoustic cue in stress perception for both adults, in whom this dominance is very strong, and typically developing children, who showed a similar but quantitatively less marked pattern. As to children with dyslexia, they did not seem to rely on any parameter for their judgments, and rather gave random responses, which point to a general inability to process the various acoustic modulations that normally contribute to stress perception. Performance on the stress perception task strongly correlates with language (morphosyntactic) measures in the whole sample of children, and with reading abilities in the group with dyslexia, confirming the strict relationship between the two sets of skills. These findings seem to support a language-specific approach, suggesting that the set of acoustic parameters required for the development of stress perception is language-dependent rather than universal.

Investigating the influence of ubiquinone blood level on the abilities of children with specific learning disorder

Background

Ubiquinone has antioxidant properties and has been linked to cognitive performance in some neuropsychiatric disorders. Its role in specific learning disorder manifestations has not been previously investigated. Therefore, the aim of this study was to measure the blood levels of ubiquinone in a group of children with specific learning disorder in comparison to typically developing children and to investigate the correlation between ubiquinone levels in children with specific learning disorder and some of their intellectual capabilities, reading, spelling and writing performance. 

Methods

The study included 71 native Arabic speaking children: 31 in the specific learning disorder group and 40 in the typically developing (TD) group. The abilities of the children with specific learning disorder were evaluated by the Stanford-Binet Intelligence Scale-4th edition, the Dyslexia Assessment Test, and the Illinois Test of Psycholinguistic Abilities. The level of ubiquinone was measured in both groups by ELISA. Correlation between some aptitudes of children with specific learning disorder and the ubiquinone level was performed.

Results

The blood levels of ubiquinone in the children with specific learning disorder group were less than those in the TD group. Correlation analysis revealed a significant positive correlation between ubiquinone and the scores of backward digit span abilities.

Conclusions

Ubiquinone has a role in the auditory working memory performance of children with specific learning disorder (with impairment in reading). The decreased levels of ubiquinone in this sample of children with specific learning disorder could have participated in the pathogenesis of this disorder.

Increased variability of stimulus-driven cortical responses is associated with genetic variability in children with and without dyslexia

Individuals with dyslexia exhibit increased brainstem variability in response to sound. It is unknown as to whether increased variability extends to neocortical regions associated with audition and reading, extends to visual stimuli, and whether increased variability characterizes all children with dyslexia or, instead, a specific subset of children. We evaluated the consistency of stimulus-evoked neural responses in children with (N = 20) or without dyslexia (N = 12) as measured by magnetoencephalography (MEG). Approximately half of the children with dyslexia had significantly higher levels of variability in cortical responses to both auditory and visual stimuli in multiple nodes of the reading network. There was a significant and positive relationship between the number of risk alleles at rs6935076 in the dyslexia-susceptibility gene KIAA0319 and the degree of neural variability in primary auditory cortex across all participants. This gene has been linked with neural variability in rodents and in typical readers. These findings indicate that unstable representations of auditory and visual stimuli in auditory and other reading-related neocortical regions are present in a subset of children with dyslexia and support the link between the gene KIAA0319 and the auditory neural variability across children with or without dyslexia.

Revisiting the "enigma" of musicians with dyslexia: Auditory sequencing and speech abilities

Previous research has suggested a link between musical training and auditory processing skills. Musicians have shown enhanced perception of auditory features critical to both music and speech, suggesting that this link extends beyond basic auditory processing. It remains unclear to what extent musicians who also have dyslexia show these specialized abilities, considering often-observed persistent deficits that coincide with reading impairments. The present study evaluated auditory sequencing and speech discrimination in 52 adults comprised of musicians with dyslexia, nonmusicians with dyslexia, and typical musicians. An auditory sequencing task measuring perceptual acuity for tone sequences of increasing length was administered. Furthermore, subjects were asked to discriminate synthesized syllable continua varying in acoustic components of speech necessary for intraphonemic discrimination, which included spectral (formant frequency) and temporal (voice onset time [VOT] and amplitude envelope) features. Results indicate that musicians with dyslexia did not significantly differ from typical musicians and performed better than nonmusicians with dyslexia for auditory sequencing as well as discrimination of spectral and VOT cues within syllable continua. However, typical musicians demonstrated superior performance relative to both groups with dyslexia for discrimination of syllables varying in amplitude information. These findings suggest a distinct profile of speech processing abilities in musicians with dyslexia, with specific weaknesses in discerning amplitude cues within speech. Because these difficulties seem to remain persistent in adults with dyslexia despite musical training, this study only partly supports the potential for musical training to enhance the auditory processing skills known to be crucial for literacy in individuals with dyslexia. (PsycINFO Database Record

Crossmodal synesthetic congruency improves visual timing in dyslexic children

Consistent with the temporal ventriloquism effect, synesthetic correspondence between the features of visual size and auditory pitch has been shown to modulate the performance of visual temporal order judgment (TOJ) in typical adults. Here in the two main experiments we recruited seventeen dyslexic children and twenty typically developing children to perform a visual TOJ task and measured their ability of synesthetic correspondence between visual size and auditory pitch. In Experiment 1, participants were shown two consecutively presented visual discs that were temporally flanked by two synesthetic congruent or incongruent auditory beeps. In Experiment 2, participants received a crossmodal matching test (visual-size vs. auditory pitch). The results showed that compared to the typically developing group, dyslexic children benefited more from cross-modal synesthetic correspondence to partially compensate for their deficiency in visual TOJ task. The multisensory facilitation for timing performance was correlated with reading ability (Exp.1). Moreover, dyslexic children formed intact "congruent" matching of visually larger shapes to lower auditory pitch, and visually smaller shapes to higher auditory pitch, as did their typically developing peers (Exp 2). The results of our present study suggested general deficits of temporal processing in dyslexic children, However, with relatively intact ability of auditory pitch-visual size matching, dyslexic children could separate visual events using auditory cues. The current study also indicates a feasible way to improve the reading ability by exploiting temporal ventriloquism effect, modulated by appropriate crossmodal synesthetic associations.

Auditory discrimination predicts linguistic outcome in Italian infants with and without familial risk for language learning impairment

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Italian infants with familial risk for LLI show deficits in RAP abilities.

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Early multi-feature RAP skills predict to later expressive language skills.

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Different acoustical features are critical to normative language acquisition.

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Early RAP skills represent a stable cross-linguistic risk marker for LLI.

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Early intervention programs should be implemented based on these results.

Infants’ ability to discriminate between auditory stimuli presented in rapid succession and differing in fundamental frequency (Rapid Auditory Processing [RAP] abilities) has been shown to be anomalous in infants at familial risk for Language Learning Impairment (LLI) and to predict later language outcomes. This study represents the first attempt to investigate RAP in Italian infants at risk for LLI (FH+), examining two critical acoustic features: frequency and duration, both embedded in a rapidly-presented acoustic environment. RAP skills of 24 FH+ and 32 control (FH−) Italian 6-month-old infants were characterized via EEG/ERP using a multi-feature oddball paradigm. Outcome measures of expressive vocabulary were collected at 20 months.

Group differences favoring FH− infants were identified: in FH+ infants, the latency of the N2* peak was delayed and the mean amplitude of the positive mismatch response was reduced, primarily for frequency discrimination and within the right hemisphere. Moreover, both EEG measures were correlated with language scores at 20 months.

Results indicate that RAP abilities are atypical in Italian infants with a first-degree relative affected by LLI and that this impacts later linguistic skills. These findings provide a compelling cross-linguistic comparison with previous research on American infants, supporting the biological unity hypothesis of LLI.