Nonlinguistic perceptual deficits associated with reading and language disorders

Comprehension of complex syntax by non-English-speaking children with developmental language disorder: A scoping review

Children with developmental language disorder (DLD) are characterised by impaired language abilities both in comprehension and production. Complex syntax is a specific domain which is often considered challenging for children with DLD. Research regarding complex syntax is mostly concerned with the production patterns of speakers and usually employs English-speaking populations. This scoping review aims to systematically map the abilities of non-English-speaking children with DLD to comprehend complex syntactic structures, comparing these results with the broader literature on English-speaking children with DLD. It also aims to consider the account (i.e. grammatical vs processing) by which these abilities can be explained. Four online databases were used to extract original research articles published between 2011 and 2021. Of the 264 studies initially identified, 20 studies were included in the review. The results demonstrated that children with DLD present with difficulties in comprehending object relative clauses, wh-questions, sentences with non-canonical word order, passives, and other types of complex syntax. All of these challenges are also evident in English-speaking children with DLD and can be mainly attributed either to the inability of children to assign thematic roles, their restricted working memory capacities, or a combination thereof. It is concluded that the comprehension of complex syntax might be a universal marker of DLD, which can be explained on the basis of either a grammatical or a processing account, or both. Common challenges in certain structures across languages can be used to design a comprehension assessment tool that can be applied in several languages.

Identifying the risk of dyslexia in bilingual children: The potential of language-dependent and language-independent tasks

This study investigates the linguistic processing and non-linguistic cognitive abilities of monolingual and bilingual children with and without reading difficulties and examines the relationship between these skills and reading. There were 72 Italian-speaking children: 18 monolingual good readers (MONO-GR, M_age = 10;4), 19 monolingual poor readers (MONO-PR, M_age = 10;3), 21 bilingual good readers (BI-GR, M_age = 10;6), and 16 bilingual poor readers (BI-PR, M_age = 10;6). All bilingual children spoke Italian as their L2. Children completed a battery of standardized Italian reading tests, language-dependent tasks: nonword repetition (NWR), sentence repetition (SR), and phonological awareness (PA), and language-independent tasks: timing anticipation, beat synchronization, inhibition control, auditory reaction time, and rapid automatized naming (RAN). Poor readers scored below good readers on the language-dependent tasks, including NWR, PA, and SR. Beat synchronization was the only language-independent task sensitive to reading ability, with poor readers showing greater variability than good readers in tapping to fast rhythms. SR was the only task influenced by language experience as bilinguals underperformed monolinguals on the task. Moreover, there were weak to moderate correlations between performance on some language-dependent tasks (NWR, PA), language-independent tasks (inhibition control, RAN), and reading measures. Performance on the experimental tasks (except for RAN) was not associated with the length of exposure to Italian. The results highlight the potential of NWR, PA, SR, and beat synchronization tasks in identifying the risk of dyslexia in bilingual populations. Future research is needed to validate these findings and to establish the tasks' diagnostic accuracy.

Specific Learning Disorder in Children and Adolescents, a Scoping Review on Motor Impairments and Their Potential Impacts

Mastering motor skills is important for children to achieve functional mobility and participate in daily activities. Some studies have identified that students with specific learning disorders (SLD) could have impaired motor skills; however, this postulate and the potential impacts remain unclear. The purpose of the scoping review was to evaluate if SLD children have motor impairments and examine the possible factors that could interfere with this assumption. The sub-objective was to investigate the state of knowledge on the lifestyle behavior and physical fitness of participants with SLD and to discuss possible links with their motor skills. Our scoping review included preregistration numbers and the redaction conformed with the PRISMA guidelines. A total of 34 studies published between 1990 and 2022 were identified. The results of our scoping review reflected that students with SLD have poorer motor skills than their peers. These motor impairments are exacerbated by the complexity of the motor activities and the presence of comorbidities. These results support our sub-objective and highlight the link between motor impairments and the sedentary lifestyle behavior of SLDs. This could lead to deteriorating health and motor skills due to a lack of motor experience, meaning that this is not necessarily a comorbidity. This evidence emphasizes the importance of systematic clinical motor assessments and physical activity adaptations.

Executive Function, Working Memory, and Verbal Fluency in Relation to Non-Verbal Intelligence in Greek-Speaking School-Age Children with Developmental Language Disorder

Developmental Language Disorder (DLD) is often associated with impairments in working memory (WM), executive functions (EF), and verbal fluency. Moreover, increasing evidence shows poorer performance of children with DLD on non-verbal intelligence tests relative to their typically developing (TD) peers. Yet, the degree and generality of relevant difficulties remain unclear. The present study aimed at investigating WM capacity, key EFs and verbal fluency in relation to non-verbal intelligence in Greek-speaking school-age children with DLD, compared to TD peers (8–9 years). To our knowledge, the present study is the first to attempt a systematic relevant assessment with Greek-speaking school-age children, complementing previous studies mostly involving English-speaking participants. The results showed that children with DLD scored lower than TD peers on the non-verbal intelligence measure. Groups did not differ in the inhibition measures obtained (tapping resistance to either distractor or proactive interference), but children with DLD were outperformed by TD peers in the WM capacity, updating, monitoring (mixing cost), and verbal fluency (phonological and semantic) measures. The effects showed limited (in the case of backward digit recall) or no dependence on non-verbal intelligence. Findings are discussed in terms of their theoretical and practical implications as well as in relation to future lines of research.

Subcortical auditory neural synchronization is deficient in pre-reading children who develop dyslexia

Auditory processing of temporal information in speech is sustained by synchronized firing of neurons along the entire auditory pathway. In school-aged children and adults with dyslexia, neural synchronization deficits have been found at cortical levels of the auditory system, however, these deficits do not appear to be present in pre-reading children. An alternative role for subcortical synchronization in reading development and dyslexia has been suggested, but remains debated. By means of a longitudinal study, we assessed cognitive reading-related skills and subcortical auditory steady-state responses (80 Hz ASSRs) in a group of children before formal reading instruction (pre-reading), after 1 year of formal reading instruction (beginning reading), and after 3 years of formal reading instruction (more advanced reading). Children were retrospectively classified into three groups based on family risk and literacy achievement: typically developing children without a family risk for dyslexia, typically developing children with a family risk for dyslexia, and children who developed dyslexia. Our results reveal that children who developed dyslexia demonstrate decreased 80 Hz ASSRs at the pre-reading stage. This effect is no longer present after the onset of reading instruction, due to an atypical developmental increase in 80 Hz ASSRs between the pre-reading and the beginning reading stage. A forward stepwise logistic regression analysis showed that literacy achievement was predictable with an accuracy of 90.4% based on a model including three significant predictors, that is, family risk for dyslexia (R = .31), phonological awareness (R = .23), and 80 Hz ASSRs (R = .26). Given that (1) abnormalities in subcortical ASSRs preceded reading acquisition in children who developed dyslexia and (2) subcortical ASSRs contributed to the prediction of literacy achievement, subcortical auditory synchronization deficits may constitute a pre-reading risk factor in the emergence of dyslexia.

Effect of READ1 on latent profiles of reading disorder and comorbid attention and language impairment subtypes

Recent studies of co-occurring reading disorder (RD) and attention deficit/hyperactivity disorder (ADHD), and co-occurring RD and language impairment (LI), support a core disability plus co-occurrence model focused on language and attention. Genetic factors have been associated with poor reading performance. However, little is known about whether different genetic variants independently contribute to RD co-occurrence subtypes. We aimed to identify subgroups of struggling readers using a latent profile analysis (LPA) in a sample of 1,432 Hispanic American and African American youth. RD classes were then tested for association with variants of READ1, a regulatory element within the candidate RD risk gene, DCDC2. Six groups were identified in the LPA using RD designation as a known-class variable. The three RD classes identified groups of subjects with neurocognitive profiles representing RD+ADHD, specific phonological deficit RD, and RD+LI. Genetic associations across RD subtypes were investigated against functional groupings of READ1. The RU1-1 group of READ1 alleles was associated with RD cases that were marked by deficits in both processing speed and attention (RD+ADHD). The DCDC2 microdeletion that encompasses READ1 was associated with RD cases showing a phonological deficit RD profile. These findings provide evidence for differential genetic contribution to RD subtypes, and that previously implicated genetic variants for RD may share an underlying genetic architecture across population groups for reading disorder.

Auditory, Visual, and Cross-Modal Temporal Processing Skills Among Chinese Children With Developmental Dyslexia

The present study examined whether temporal processing (TP) is associated with reading of a non-alphabetic script, that is, Chinese. A total of 126 primary school-aged Chinese children from Taiwan (63 children with dyslexia) completed cross-modal, visual, and auditory temporal order judgment tasks and measures of Chinese reading and literacy-related skills. The results showed that typically developing children and children with dyslexia differed in all TP skills. Structural equation modeling indicated that cross-modal TP contributed independently to character recognition in the entire sample if the significant effects of phonological awareness, orthographic knowledge, and rapid automatized naming were considered. The multi-sample analysis showed that TP did not predict reading in the typical group after controlling for literacy-related skills, but visual and cross-modal TP skills independently contributed to reading in the group with dyslexia in addition to literacy-related skills. Finally, the path analysis indicated that in the typical group, separate TP skills affected reading through literacy-related skills, but visual and cross-modal TP skills had direct effects on character reading in the group with dyslexia. These findings suggest that TP is more important for reading in children with dyslexia than in typically developing children, and the roles of TP in dyslexia require further examination.

Behind the Scenes of Developmental Language Disorder: Time to Call Neuropsychology Back on Stage

Although the Developmental Language Disorder (DLD), also known as Specific Language Impairment in children has been the focus of unceasing scientific attention for decades, the nature and mechanisms of this disorder remain unclear. Most importantly, we still cannot reliably identify children requiring urgent intervention among other ‘late talkers’ at an early age and understand the high prevalence of comorbidity with psychiatric phenomena such as Autism Spectrum Disorder. One of the main reasons for this is the traditional ‘diagnosis-by-exclusion,’ resulting in heterogeneity of the DLD population. This paper proposes an alternative approach to the diagnosis, treatment and research of DLD, claiming that it is these children’s multiple deficits in neuropsychological development, which impede the spontaneous acquisition of their first language. Specifically, this review of the state-of-the-art in DLD research demonstrates deep and systematic interconnections between the speech and other higher cognitive functions developing in early childhood, including perception, attention and executive functions. In the proposed framework, speech is, therefore, considered as one of neuropsychological abilities, and the delay in its development is explained by other neuropsychological deficits, resulting in highly individual clinical profiles. By considering DLD as a complex neuropsychological syndrome, whose successful treatment depends on a holistic approach to diagnosis and intervention, we may significantly increase the efficacy of speech therapy, and also better understand the flexibility of the developing brain, its compensatory mechanisms and hence the comorbidity of DLD with psychiatric symptoms. Implications for using this paradigm in future scientific research are discussed.

Efficient assessment of the time course of perceptual sensitivity change

Perceptual sensitivity is usually estimated over trials and time intervals, which results in imprecise and biased estimates when it changes rapidly over time. We develop a novel procedure, the quick Change-Detection (qCD) method, to accurately, precisely, and efficiently assess the trial-by-trial time course of perceptual sensitivity change. Based on Bayesian adaptive testing, qCD selects the optimal stimulus, and updates, trial by trial, a joint probability distribution of the parameters that quantify perceptual sensitivity change over time. We demonstrate the utility of the method in measuring the time course of dark adaptation. Simulations showed that the accuracy and precision of the estimated dark adaptation curve after one qCD run (root mean squared error (RMSE): 0.002; the half width of the 68.2% credible interval (HWCI): 0.016; standard deviation (SD): 0.020; all in log₁₀ units) was higher than those obtained by ten runs of the quick Forced-Choice (qFC) procedure (RMSE: 0.020; HWCI: 0.032; SD: 0.031) and ten runs of a weighted up-down staircase procedure (RMSE: 0.026; SD: 0.031). Further, the dark adaptation curve obtained from one qCD run in a psychophysics experiment was highly consistent with the average of four qFC runs (RMSE = 0.076 log₁₀ units). Overall, qCD provides a procedure to characterize the detailed time course of perceptual sensitivity change in both basic research and clinical applications.

Dyslexia as a multi-deficit disorder: Working memory and auditory temporal processing

Dyslexia is difficulty in acquiring reading skills despite adequate intelligence and sufficient reading opportunities. Its origin is still under debate. Studies usually focus on a singular cause for dyslexia; however, some researchers argue that dyslexia reflects multiple deficits. Two of the abilities under investigation in dyslexia are working memory (WM) and auditory temporal processing (ATP). In order to better evaluate the relative roles of WM and ATP in dyslexia, in the present study, we tested the contribution of WM and ATP to different types of reading performance and phonological awareness in dyslexia, using a multidimensional approach. Seventy-eight adults with dyslexia and 23 normal-reading adults performed WM and ATP tasks, as well as reading and phonological awareness tests. Readers with dyslexia showed poorer performance on all tests. Both WM and ATP were significant predictors of reading performance and phonological awareness among participants with dyslexia. Dividing participants with dyslexia according to their performance level on WM and ATP tasks revealed group differences in reading and phonological awareness tests. Both WM and ATP contribute to dyslexia, and varying levels of difficulties in both of these abilities are observed among this population. This is strong evidence in favor of the multi-deficit approach in dyslexia, and suggests that researchers should consider this approach in future studies of dyslexia.

Beyond Auditory Sensory Processing Deficits: Lexical Tone Perception Deficits in Chinese Children With Developmental Dyslexia

Increasing evidence suggests that children with developmental dyslexia exhibit a deficit not only at the segmental level of phonological processing but also, by extension, at the suprasegmental level. However, it remains unclear whether such a suprasegmental phonological processing deficit is due to a difficulty in processing acoustic cues of speech rhythm, such as rise time and intensity. This study set out to investigate to what extent suprasegmental phonological processing (i.e., Cantonese lexical tone perception) and rise time sensitivity could distinguish Chinese children with dyslexia from typically developing children. Sixteen children with dyslexia and 44 age-matched controls were administered a Cantonese lexical tone perception task, psychoacoustic tasks, a nonverbal reasoning ability task, and word reading and dictation tasks. Children with dyslexia performed worse than controls on Cantonese lexical tone perception, rise time, and intensity. Furthermore, Cantonese lexical tone perception appeared to be a stable indicator that distinguishes children with dyslexia from controls, even after controlling for basic auditory processing skills. These findings suggest that suprasegmental phonological processing (i.e., lexical tone perception) is a potential factor that accounts for reading difficulty in Chinese.

Picture naming in typically developing and language-impaired children: the role of sustained attention

BACKGROUND

Children with specific language impairment (SLI) have problems not only with language performance but also with sustained attention, which is the ability to maintain alertness over an extended period of time. Although there is consensus that this ability is impaired with respect to processing stimuli in the auditory perceptual modality, conflicting evidence exists concerning the visual modality.

AIMS

To address the outstanding issue whether the impairment in sustained attention is limited to the auditory domain, or if it is domain-general. Furthermore, to test whether children's sustained attention ability relates to their word-production skills.

METHODS & PROCEDURES

Groups of 7-9 year olds with SLI (N = 28) and typically developing (TD) children (N = 22) performed a picture-naming task and two sustained attention tasks, namely auditory and visual continuous performance tasks (CPTs).

OUTCOMES & RESULTS

Children with SLI performed worse than TD children on picture naming and on both the auditory and visual CPTs. Moreover, performance on both the CPTs correlated with picture-naming latencies across developmental groups.

CONCLUSIONS & IMPLICATIONS

These results provide evidence for a deficit in both auditory and visual sustained attention in children with SLI. Moreover, the study indicates there is a relationship between domain-general sustained attention and picture-naming performance in both TD and language-impaired children. Future studies should establish whether this relationship is causal. If attention influences language, training of sustained attention may improve language production in children from both developmental groups.

Neural Mechanisms of Language-Based Learning Impairments: Insights from Human Populations and Animal Models

The acquisition of speech perception and consequent expression of language represent fundamental aspects of human functioning. Yet roughly 7% to 8% of children who are otherwise healthy and of normal intelligence exhibit unexplained delays and impairments in acquiring these skills. Ongoing research has revealed several key features of language disability that may pro-vide more direct insight into underlying anomalous neural functioning. For example, evidence supports a strong association between basic defects in processing rapidly changing acoustic information and emergent disruptions in speech perception, as well as cascading effects on other forms of language development (including reading). Considerable neurobiological research has thus focused on developmental factors that might deleteriously influence rapid sensory processing. Additional research focuses on mechanisms of neural plasticity, including how such brains might be “retrained” for improved processing of language. These and related findings from human clinical studies, electrophysiological studies, neuroimaging studies, and animal models are reviewed.

Visual Illusions: An Interesting Tool to Investigate Developmental Dyslexia and Autism Spectrum Disorder

A visual illusion refers to a percept that is different in some aspect from the physical stimulus. Illusions are a powerful non-invasive tool for understanding the neurobiology of vision, telling us, indirectly, how the brain processes visual stimuli. There are some neurodevelopmental disorders characterized by visual deficits. Surprisingly, just a few studies investigated illusory perception in clinical populations. Our aim is to review the literature supporting a possible role for visual illusions in helping us understand the visual deficits in developmental dyslexia and autism spectrum disorder. Future studies could develop new tools - based on visual illusions - to identify an early risk for neurodevelopmental disorders.

Auditory scene analysis in school-aged children with developmental language disorders

Natural sound environments are dynamic, with overlapping acoustic input originating from simultaneously active sources. A key function of the auditory system is to integrate sensory inputs that belong together and segregate those that come from different sources. We hypothesized that this skill is impaired in individuals with phonological processing difficulties. There is considerable disagreement about whether phonological impairments observed in children with developmental language disorders can be attributed to specific linguistic deficits or to more general acoustic processing deficits. However, most tests of general auditory abilities have been conducted with a single set of sounds. We assessed the ability of school-aged children (7-15 years) to parse complex auditory non-speech input, and determined whether the presence of phonological processing impairments was associated with stream perception performance. A key finding was that children with language impairments did not show the same developmental trajectory for stream perception as typically developing children. In addition, children with language impairments required larger frequency separations between sounds to hear distinct streams compared to age-matched peers. Furthermore, phonological processing ability was a significant predictor of stream perception measures, but only in the older age groups. No such association was found in the youngest children. These results indicate that children with language impairments have difficulty parsing speech streams, or identifying individual sound events when there are competing sound sources. We conclude that language group differences may in part reflect fundamental maturational disparities in the analysis of complex auditory scenes.

Development of the auditory system

Auditory development involves changes in the peripheral and central nervous system along the auditory pathways, and these occur naturally, and in response to stimulation. Human development occurs along a trajectory that can last decades, and is studied using behavioral psychophysics, as well as physiologic measurements with neural imaging. The auditory system constructs a perceptual space that takes information from objects and groups, segregates sounds, and provides meaning and access to communication tools such as language. Auditory signals are processed in a series of analysis stages, from peripheral to central. Coding of information has been studied for features of sound, including frequency, intensity, loudness, and location, in quiet and in the presence of maskers. In the latter case, the ability of the auditory system to perform an analysis of the scene becomes highly relevant. While some basic abilities are well developed at birth, there is a clear prolonged maturation of auditory development well into the teenage years. Maturation involves auditory pathways. However, non-auditory changes (attention, memory, cognition) play an important role in auditory development. The ability of the auditory system to adapt in response to novel stimuli is a key feature of development throughout the nervous system, known as neural plasticity.

Central auditory processing disorders in children and adults

Central auditory processing disorders (CAPD) can affect children and adults of all ages due to a wide variety of causes. CAPD is a neurobiologic deficit in the central auditory nervous system (CANS) that affects those mechanisms that underlie fundamental auditory perception, including localization and lateralization; discrimination of speech and non-speech sounds; auditory pattern recognition; temporal aspects of audition, including integration, resolution, ordering, and masking; and auditory performance with competing and/or degraded acoustic signals (American Speech-Language-Hearing Association, 2005a, b). Although it is recognized that central auditory dysfunction may coexist with other disorders, CAPD is conceptualized as a sensory-based auditory disorder. Administration of behavioral and/or electrophysiologic audiologic tests that have been shown to be sensitive and specific to dysfunction of the CANS is critical for a proper diagnosis of CAPD, in addition to assessments and collaboration with a multidisciplinary team. Intervention recommendations for CAPD diagnosis are based on the demonstrated auditory processing deficits and related listening and related complaints. This chapter provides an overview of current definitions and conceptualizations, methods of diagnosis of, and intervention for, CAPD. The chapter culminates with a case study illustrating pre- and posttreatment behavioral and electrophysiologic diagnostic findings.

Magnocellular-dorsal pathway and sub-lexical route in developmental dyslexia

Although developmental dyslexia (DD) is frequently associate with a phonological deficit, the underlying neurobiological cause remains undetermined. Recently, a new model, called "temporal sampling framework" (TSF), provided an innovative prospect in the DD study. TSF suggests that deficits in syllabic perception at a specific temporal frequencies are the critical basis for the poor reading performance in DD. This approach was presented as a possible neurobiological substrate of the phonological deficit of DD but the TSF can also easily be applied to the visual modality deficits. The deficit in the magnocellular-dorsal (M-D) pathway - often found in individuals with DD - fits well with a temporal oscillatory deficit specifically related to this visual pathway. This study investigated the visual M-D and parvocellular-ventral (P-V) pathways in dyslexic and in chronological age and IQ-matched normally reading children by measuring temporal (frequency doubling illusion) and static stimuli sensitivity, respectively. A specific deficit in M-D temporal oscillation was found. Importantly, the M-D deficit was selectively shown in poor phonological decoders. M-D deficit appears to be frequent because 75% of poor pseudo-word readers were at least 1 SD below the mean of the controls. Finally, a replication study by using a new group of poor phonological decoders and reading level controls suggested a crucial role of M-D deficit in DD. These results showed that a M-D deficit might impair the sub-lexical mechanisms that are critical for reading development. The possible link between these findings and TSF is discussed.

Spatial and temporal attention in developmental dyslexia

Although the dominant view posits that developmental dyslexia (DD) arises from a deficit in phonological processing, emerging evidence suggest that DD could result from a more basic cross-modal letter-to-speech sound integration deficit. Letters have to be precisely selected from irrelevant and cluttering letters by rapid orienting of visual attention before the correct letter-to-speech sound integration applies. In the present study the time-course of spatial attention was investigated measuring target detection reaction times (RTs) in a cuing paradigm, while temporal attention was investigated by assessing impaired identification of the first of two sequentially presented masked visual objects. Spatial and temporal attention were slower in dyslexic children with a deficit in pseudoword reading (N = 14) compared to chronological age (N = 43) and to dyslexics without a deficit in pseudoword reading (N = 18), suggesting a direct link between visual attention efficiency and phonological decoding skills. Individual differences in these visual attention mechanisms were specifically related to pseudoword reading accuracy in dyslexics. The role of spatial and temporal attention in the graphemic parsing process might be related to a basic oscillatory "temporal sampling" dysfunction.

Integration over multiple timescales in primary auditory cortex

Speech and other natural vocalizations are characterized by large modulations in their sound envelope. The timing of these modulations contains critical information for discrimination of important features, such as phonemes. We studied how depression of synaptic inputs, a mechanism frequently reported in cortex, can contribute to the encoding of envelope dynamics. Using a nonlinear stimulus-response model that accounted for synaptic depression, we predicted responses of neurons in ferret primary auditory cortex (A1) to stimuli with natural temporal modulations. The depression model consistently performed better than linear and second-order models previously used to characterize A1 neurons, and it produced more biologically plausible fits. To test how synaptic depression can contribute to temporal stimulus integration, we used nonparametric maximum a posteriori decoding to compare the ability of neurons showing and not showing depression to reconstruct the stimulus envelope. Neurons showing evidence for depression reconstructed stimuli over a longer range of latencies. These findings suggest that variation in depression across the cortical population supports a rich code for representing the temporal dynamics of natural sounds.

Physiologic discrimination of stop consonants relates to phonological skills in pre-readers: a biomarker for subsequent reading ability?(†)

Reading development builds upon the accurate representation of the phonological structure of spoken language. This representation and its neural foundations have been studied extensively with respect to reading due to pervasive performance deficits on basic phonological tasks observed in children with dyslexia. The subcortical auditory system - a site of intersection for sensory and cognitive input - is exquisitely tuned to code fine timing differences between phonemes, and so likely plays a foundational role in the development of phonological processing and, eventually, reading. This temporal coding of speech varies systematically with reading ability in school age children. Little is known, however, about subcortical speech representation in pre-school age children. We measured auditory brainstem responses to the stop consonants [ba] and [ga] in a cohort of 4-year-old children and assessed their phonological skills. In a typical auditory system, brainstem responses to [ba] and [ga] are out of phase (i.e., differ in time) due to formant frequency differences in the consonant-vowel transitions of the stimuli. We found that children who performed worst on the phonological awareness task insufficiently code this difference, revealing a physiologic link between early phonological skills and the neural representation of speech. We discuss this finding in light of existing theories of the role of the auditory system in developmental dyslexia, and argue for a systems-level perspective for understanding the importance of precise temporal coding for learning to read.

Neuroplasticity-based cognitive and linguistic skills training improves reading and writing skills in college students

This study reports an evaluation of the effect of computer-based cognitive and linguistic training on college students' reading and writing skills. The computer-based training included a series of increasingly challenging software programs that were designed to strengthen students' foundational cognitive skills (memory, attention span, processing speed, and sequencing) in the context of listening and higher level reading tasks. Twenty-five college students (12 native English language; 13 English Second Language), who demonstrated poor writing skills, participated in the training group. The training group received daily training during the spring semester (11 weeks) with the Fast ForWord Literacy (FFW-L) and upper levels of the Fast ForWord Reading series (Levels 3-5). The comparison group (n = 28) selected from the general college population did not receive training. Both the training and comparison groups attended the same university. All students took the Gates MacGinitie Reading Test (GMRT) and the Oral and Written Language Scales (OWLS) Written Expression Scale at the beginning (Time 1) and end (Time 2) of the spring college semester. Results from this study showed that the training group made a statistically greater improvement from Time 1 to Time 2 in both their reading skills and their writing skills than the comparison group. The group who received training began with statistically lower writing skills before training, but exceeded the writing skills of the comparison group after training.

Contribution of temporal processing skills to reading comprehension in 8-year-olds: evidence for a mediation effect of phonological awareness

This study tested whether the association between temporal processing (TP) and reading is mediated by phonological awareness (PA) in a normative sample of 615 eight-year-olds. TP was measured with auditory and bimodal (visual-auditory) temporal order judgment tasks and PA with a phoneme deletion task. PA partially mediated the association between both auditory and bimodal TP and reading, above nonverbal abilities, vocabulary, and processing speed. PA explained a larger proportion of the association between auditory TP and reading (56% vs. 39% for bimodal TP), and most of the association between bimodal TP and reading was direct. This finding is consistent with a dual-phonological and visual-pathway model of the association between TP and reading in normative reading skills.

Noise on, voicing off: Speech perception deficits in children with specific language impairment

Speech perception of four phonetic categories (voicing, place, manner, and nasality) was investigated in children with specific language impairment (SLI) (n=20) and age-matched controls (n=19) in quiet and various noise conditions using an AXB two-alternative forced-choice paradigm. Children with SLI exhibited robust speech perception deficits in silence, stationary noise, and amplitude-modulated noise. Comparable deficits were obtained for fast, intermediate, and slow modulation rates, and this speaks against the various temporal processing accounts of SLI. Children with SLI exhibited normal "masking release" effects (i.e., better performance in fluctuating noise than in stationary noise), again suggesting relatively spared spectral and temporal auditory resolution. In terms of phonetic categories, voicing was more affected than place, manner, or nasality. The specific nature of this voicing deficit is hard to explain with general processing impairments in attention or memory. Finally, speech perception in noise correlated with an oral language component but not with either a memory or IQ component, and it accounted for unique variance beyond IQ and low-level auditory perception. In sum, poor speech perception seems to be one of the primary deficits in children with SLI that might explain poor phonological development, impaired word production, and poor word comprehension.

Global processing speed in children with low reading ability and in children and adults with typical reading ability: exploratory factor analytic models

PURPOSE

To investigate processing speed as a latent dimension in children with dyslexia and children and adults with typical reading skills.

METHOD

Exploratory factor analysis (FA) was based on a sample of multigenerational families, each ascertained through a child with dyslexia. Eleven measures--6 of them timed--represented verbal and nonverbal processes, alphabet writing, and motor sequencing in the hand and oral motor system. FA was conducted in 4 cohorts (all children, a subset of children with low reading scores, a subset of children with typical reading scores, and adults with typical reading scores; total N = 829).

RESULTS

Processing speed formed the first factor in all cohorts. Both measures of motor sequencing speed loaded on the speed factor with the other timed variables. Children with poor reading scores showed lower speed factor scores than did typical peers. The speed factor was negatively correlated with age in the adults.

CONCLUSIONS

The speed dimension was observed independently of participant cohort, gender, and reading ability. Results are consistent with a unified theory of processing speed as a quadratic function of age in typical development and with slowed processing in poor readers.

Auditive Verarbeitungs- und Wahrnehmungsstörungen (AVWS) im Kindesalter

Auditive Verarbeitungs- und Wahrnehmungsstörungen (AVWS) sind umschriebene Funktionsdefizite in der auditiven Informationsverarbeitung und Wahrnehmung bei intaktem peripherem Gehör und mindestens durchschnittlicher Intelligenz. Häufig sind Lernstörungen, primäre bzw. sekundäre Spracherwerbsstörungen, supramodale Aufmerksamkeitsprobleme oder tiefgreifende Entwicklungsstörungen mit AVWS im Sinn von Komorbidität assoziiert. Deswegen erscheint Eltern, Lehrern oder Untersuchern das AVWS-Konzept zur Erklärung solcher Entwicklungs- und Lernauffälligkeiten plausibel. Da Sprachsignale zerebral anders als nicht sprachliche Signale ausgewertet werden, kann Sprachwahrnehmung allenfalls als ein Spezialfall der auditiven Verarbeitung und Wahrnehmung betrachtet werden. Kausale Beziehungen zwischen gestörten auditiven Funktionen und klinischen Störungsbildern wurden bislang nicht zuverlässig belegt. Es besteht ein Mangel an kontrollierten bzw. randomisierten Therapiestudien.

Increasing genotype-phenotype model determinism: application to bivariate reading/language traits and epistatic interactions in language-impaired families

While advances in network and pathway analysis have flourished in the era of genome-wide association analysis, understanding the genetic mechanism of individual loci on phenotypes is still readily accomplished using genetic modeling approaches. Here, we demonstrate two novel genotype-phenotype models implemented in a flexible genetic modeling platform. The examples come from analysis of families with specific language impairment (SLI), a failure to develop normal language without explanatory factors such as low IQ or inadequate environment. In previous genome-wide studies, we observed strong evidence for linkage to 13q21 with a reading phenotype in language-impaired families. First, we elucidate the genetic architecture of reading impairment and quantitative language variation in our samples using a bivariate analysis of reading impairment in affected individuals jointly with language quantitative phenotypes in unaffected individuals. This analysis largely recapitulates the baseline analysis using the categorical trait data (posterior probability of linkage (PPL) = 80%), indicating that our reading impairment phenotype captured poor readers who also have low language ability. Second, we performed epistasis analysis using a functional coding variant in the brain-derived neurotrophic factor (BDNF) gene previously associated with reduced performance on working memory tasks. Modeling epistasis doubled the evidence on 13q21 and raised the PPL to 99.9%, indicating that BDNF and 13q21 susceptibility alleles are jointly part of the genetic architecture of SLI. These analyses provide possible mechanistic insights for further cognitive neuroscience studies based on the models developed herein.

Computer-based auditory training (CBAT): benefits for children with language- and reading-related learning difficulties

This article reviews the evidence for computer-based auditory training (CBAT) in children with language, reading, and related learning difficulties, and evaluates the extent it can benefit children with auditory processing disorder (APD). Searches were confined to studies published between 2000 and 2008, and they are rated according to the level of evidence hierarchy proposed by the American Speech-Language Hearing Association (ASHA) in 2004. We identified 16 studies of two commercially available CBAT programs (13 studies of Fast ForWord (FFW) and three studies of Earobics) and five further outcome studies of other non-speech and simple speech sounds training, available for children with language, learning, and reading difficulties. The results suggest that, apart from the phonological awareness skills, the FFW and Earobics programs seem to have little effect on the language, spelling, and reading skills of children. Non-speech and simple speech sounds training may be effective in improving children's reading skills, but only if it is delivered by an audio-visual method. There is some initial evidence to suggest that CBAT may be of benefit for children with APD. Further research is necessary, however, to substantiate these preliminary findings.

Visual spatial attention and speech segmentation are both impaired in preschoolers at familial risk for developmental dyslexia

Phonological skills are foundational of reading acquisition and impaired phonological processing is widely assumed to characterize dyslexic individuals. However, reading by phonological decoding also requires rapid selection of sublexical orthographic units through serial attentional orienting, and recent studies have shown that visual spatial attention is impaired in dyslexic children. Our study investigated these different neurocognitive dysfunctions, before reading acquisition, in a sample of preschoolers including children with (N=20) and without (N=67) familial risk for developmental dyslexia. Children were tested on phonological skills, rapid automatized naming, and visual spatial attention. At-risk children presented deficits in both visual spatial attention and syllabic segmentation at the group level. Moreover, the combination of visual spatial attention and syllabic segmentation scores was more reliable than either single measure for the identification of at-risk children. These findings suggest that both visuo-attentional and perisylvian-auditory dysfunctions might adversely affect reading acquisition, and may offer a new approach for early identification and remediation of developmental dyslexia.

Childhood auditory processing disorder as a developmental disorder: the case for a multi-professional approach to diagnosis and management

Auditory processing disorder (APD) is diagnosed when a patient presents with listening difficulties which can not be explained by a peripheral hearing impairment or higher-order cognitive or language problems. This review explores the association between auditory processing disorder (APD) and other specific developmental disorders such as dyslexia and attention-deficit hyperactivity disorder. The diagnosis and aetiology of APD are similar to those of other developmental disorders and it is well established that APD often co-occurs with impairments of language, literacy, and attention. The genetic and neurological causes of APD are poorly understood, but developmental and behavioural genetic research with other disorders suggests that clinicians should expect APD to co-occur with other symptoms frequently. The clinical implications of co-occurring symptoms of other developmental disorders are considered and the review concludes that a multi-professional approach to the diagnosis and management of APD, involving speech and language therapy and psychology as well as audiology, is essential to ensure that children have access to the most appropriate range of support and interventions.

Effects of dyslexia on postural control in adults

Dyslexia has been shown to affect postural control. The aim of the present study was to investigate the difference in postural stability measured as torque variance in an adult dyslexic group (n=14, determined using the Adult Dyslexia Checklist (ADCL) and nonsense word repetition test) and an adult non-dyslexic group (n=39) on a firm surface and on a foam block and with eyes open and eyes closed. Another aim was to investigate the correlation between ADCL scores and postural stability. Findings showed that ADCL scores correlated with torque variance in the anteroposterior direction on foam with eyes closed (p=0.001) and in the lateral direction on the foam surface with eyes closed (p=0.040) and open (p=0.010). General Linear Model analysis showed that high dyslexia scores were associated with increased torque variance (p<0.001). However, we found no significant difference between dyslexics and non-dyslexics, though there were indications of larger torque variance in the dyslexics. The findings suggest that adults with high dyslexic ADCL scores may experience sub-clinical balance deficits. Hence, assessing motor ability and postural control in those with high ADCL scores is motivated.

Detection and identification of monaural and binaural pitch contours in dyslexic listeners

The use of binaural pitch stimuli to test for the presence of binaural auditory impairment in reading-disabled subjects has so far led to contradictory outcomes. While some studies found that a majority of dyslexic subjects was unable to perceive binaural pitch, others obtained a clear response of dyslexic listeners to Huggins' pitch (HP). The present study clarified whether impaired binaural pitch perception is found in dyslexia. Results from a pitch contour identification test, performed in 31 dyslexic listeners and 31 matched controls, clearly showed that dyslexics perceived HP as well as the controls. Both groups also showed comparable results with a similar-sounding, but monaurally detectable, pitch-evoking stimulus. However, nine of the dyslexic subjects were found to have difficulty identifying pitch contours both in the binaural and the monaural conditions. The ability of subjects to correctly identify pitch contours was found to be significantly correlated to measures of frequency discrimination. This correlation may be attributed to the similarity of the experimental tasks and probably reflects impaired cognitive mechanisms related to auditory memory or auditory attention rather than impaired low-level auditory processing per se.

Auditory stream biasing in children with reading impairments

Reading impairments have previously been associated with auditory processing differences. We examined auditory stream biasing, a global aspect of auditory temporal processing. Children with reading impairments, control children and adults heard a 10 s long stream-bias-inducing sound sequence (a repeating 1000 Hz tone) and a test sequence (eight repetitions of two pure tones of 1000 and 1420 Hz in an XYX-XYX... pattern) with a variable delay interval (from 0.09 to 8 s) between the two sequences. Reading-impaired children had a significantly lower proportion of streamed responses than control children and adults. Streamed responses in reading-impaired participants differed according to their musical experience, but musically experienced reading-impaired participants were still significantly different from musically experienced controls. Reading impairments are associated with global differences in auditory integration, and musical experience needs to be considered when investigating auditory processing capabilities.

Subcortical differentiation of stop consonants relates to reading and speech-in-noise perception

Children with reading impairments have deficits in phonological awareness, phonemic categorization, speech-in-noise perception, and psychophysical tasks such as frequency and temporal discrimination. Many of these children also exhibit abnormal encoding of speech stimuli in the auditory brainstem, even though responses to click stimuli are normal. In typically developing children the auditory brainstem response reflects acoustic differences between contrastive stop consonants. The current study investigated whether this subcortical differentiation of stop consonants was related to reading ability and speech-in-noise performance. Across a group of children with a wide range of reading ability, the subcortical differentiation of 3 speech stimuli ([ba], [da], [ga]) was found to be correlated with phonological awareness, reading, and speech-in-noise perception, with better performers exhibiting greater differences among responses to the 3 syllables. When subjects were categorized into terciles based on phonological awareness and speech-in-noise performance, the top-performing third in each grouping had greater subcortical differentiation than the bottom third. These results are consistent with the view that the neural processes underlying phonological awareness and speech-in-noise perception depend on reciprocal interactions between cognitive and perceptual processes.

[Significance of auditory perceptual disorders for pediatric and adolescent psychiatric disorders]

The clinical relevance of central auditory processing disorders (CAPD) is highly controversial. The paper explicates different concepts of CAPD and reviews empirical studies of the relationship between auditory deficits and learning or psychiatric disorders. The overview of the available literature reveals that numerous authors have described subnormal auditory abilities in groups of children with developmental language disorders, dyslexia or ADHD. However, little or no relationship between the severity of clinical impairment and auditory deficits has been found. Thus auditory deficits do not appear to be causally related to learning disorders or conduct disorders. With respect to the diagnostic process the review makes clear that the validity of the diagnosis CAPD is low. There is no agreement about diagnostic criteria, and the reliability of most auditory tests in insufficient. Moreover, while an auditory training can only improve the directly trained auditory functions, there is no transfer effect to learning ability of behavior. Altogether there is little evidence for a significant relevance of CAPD in Child and Adolescent Psychiatry.

An Evaluation of the Validity of the Test of Visual Perceptual Skills - Revised (TVPS-R) Using the Rasch Measurement Model

The visual perceptual skills of children are often evaluated by health care and education practitioners. Even though the Test of Visual Perceptual Skills - Revised (TVPS-R) is one of the most frequently used instruments with school-age children, its construct validity has not been evaluated thoroughly. The purpose of the study was to evaluate the scalability/interval level measurement, unidimensionality, lack of differential item functioning (DIF), and hierarchical ordering of items of the TVPS-R and its seven subscales using the Rasch Measurement Model (RMM). The TVPS-R scores from a sample of 356 normally developing children (171 boys and 185 girls), ranging in age from 5 to 11 years, were used to complete the RMM analysis.

When the seven individual TVPS-R scales were analysed, they all exhibited adequate measurement properties (scalability/interval level measurement, unidimensionality, lack of DIF, and hierarchical ordering). However, when they were collapsed together to form an overall composite scale of motor-free visual perceptual skills, the TVPS-R items failed to group together to measure a unidimensional construct. In addition, many scale items exhibited RMM misfit or DIF.

The results suggest that the seven TVPS-R subscales can be used on an individual basis with clients to generate a profile of their motor-free visual perceptual skills, but that they cannot be summed together to calculate an overall summary motor-free visual perceptual score or perceptual quotient. The TVPS-R composite scale does not exhibit adequate construct validity.

Wide and Diffuse Perceptual Modes Characterize Dyslexics in Vision and Audition

We examined the performance of dyslexic and typically reading children on two analogous recognition tasks: one visual and the other auditory. Both tasks required recognition of centrally and peripherally presented stimuli. Dyslexics recognized letters visually farther in the periphery and more diffuse near the center than typical readers did. Both groups performed comparably in recognizing centrally spoken stimuli presented without peripheral interference, but in the presence of a surrounding speech mask (the ‘cocktail-party effect’) dyslexics recognized the central stimuli significantly less well than typical readers. However, dyslexics had a higher ratio of the number of words recognized from the surrounding speech mask, relative to the ones from the center, than typical readers did. We suggest that the evidence of wide visual and auditory perceptual modes in dyslexics indicates wider multi-dimensional neural tuning of sensory processing interacting with wider spatial attention.

Delayed detection of tonal targets in background noise in dyslexia

Individuals with developmental dyslexia are often impaired in their ability to process certain linguistic and even basic non-linguistic auditory signals. Recent investigations report conflicting findings regarding impaired low-level binaural detection mechanisms associated with dyslexia. Binaural impairment has been hypothesized to stem from a general low-level processing disorder for temporally fine sensory stimuli. Here we use a new behavioral paradigm to address this issue. We compared the response times of dyslexic listeners and their matched controls in a tone-in-noise detection task. The tonal signals were either Huggins Pitch (HP), a stimulus requiring binaural processing to elicit a pitch percept, or a pure tone-perceptually similar but physically very different signals. The results showed no difference between the two groups specific to the processing of HP and thus no evidence for a binaural impairment in dyslexia. However, dyslexic subjects exhibited a general difficulty in extracting tonal objects from background noise, manifested by a globally delayed detection speed.

Detection of sinusoidal amplitude modulated sounds: deficits after bilateral lesions of auditory cortex in the rat

The ability of rats to detect the presence of sinusoidal amplitude modulation (AM) of a broadband noise carrier was determined before and after bilateral ablation of auditory cortex. The rats were trained to withdraw from a drinking spout to avoid a shock when they detected a modulation of the sound. Sensitivity was evaluated by testing the rats at progressively smaller depths of modulation. Psychophysical curves were produced to describe the limits of detection at modulation rates of 10, 100 and 1000Hz. Performance scores were based on the probability of withdrawal from the spout during AM (warning periods) relative to withdrawal during the un-modulated noise (safe periods). A threshold was defined as the depth of modulation that produced a score halfway between perfect avoidance and no avoidance (performance score=0.5). Bilateral auditory cortical lesions resulted in significant elevations in threshold for detection of AM at rates of 100 and 1000Hz. No significant shift was found at a modulation rate of 10Hz. The magnitude of the deficit for AM rates of 100 and 1000Hz was positively correlated with the size of the cortical lesion. Substantial deficits were found only in animals with lesions that included secondary as well as primary auditory cortical areas. The results show that the rat's auditory cortex is important for processing sinusoidal AM and that its contribution is most apparent at high modulation rates. The data suggest that the auditory cortex is a crucial structure for maintaining normal sensitivity to temporal modulation of an auditory stimulus.

Variation in the normal hearing threshold predicts childhood IQ, linguistic, and behavioral outcomes

Childhood hearing level varies considerably within the range considered normal. Four classes of outcome were investigated for associations with hearing thresholds in this range: ability to identify speech in noise, neurocognitive ability, linguistic ability, and behavior. The research was conducted in a general population cohort of 711 children with mean hearing threshold of 15 dB HL or better. Some outcomes: speech in noise, intelligence, and certain linguistic abilities, were predicted in both boys and girls; effects were stronger in girls. In girls only, poorer hearing predicted worse behavior. These effects remained after statistical control for childhood socioeconomic status and otitis media. Variability in normal hearing, due to causes other than otitis media, is associated with the listening, language, and neurocognitive abilities of children, and the behavior of girls. We suggest that these effects may be present for three reasons, cochlear insults, neurodevelopmental factors, and psychological factors. We discuss how these may interact to produce the effects observed.