The Experts below are selected from a list of 9387 Experts worldwide ranked by ideXlab platform
Usha Goswami - One of the best experts on this subject based on the ideXlab platform.
-
neural encoding of the speech envelope by children with Developmental Dyslexia
Brain and Language, 2016Co-Authors: Alan J Power, Natasha Mead, Lincoln J Colling, Lisa Barnes, Usha GoswamiAbstract:Developmental Dyslexia is consistently associated with difficulties in processing phonology (linguistic sound structure) across languages. One view is that Dyslexia is characterised by a cognitive impairment in the "phonological representation" of word forms, which arises long before the child presents with a reading problem. Here we investigate a possible neural basis for Developmental phonological impairments. We assess the neural quality of speech encoding in children with Dyslexia by measuring the accuracy of low-frequency speech envelope encoding using EEG. We tested children with Dyslexia and chronological age-matched (CA) and reading-level matched (RL) younger children. Participants listened to semantically-unpredictable sentences in a word report task. The sentences were noise-vocoded to increase reliance on envelope cues. Envelope reconstruction for envelopes between 0 and 10Hz showed that the children with Dyslexia had significantly poorer speech encoding in the 0-2Hz band compared to both CA and RL controls. These data suggest that impaired neural encoding of low frequency speech envelopes, related to speech prosody, may underpin the phonological deficit that causes Dyslexia across languages.
-
sensory theories of Developmental Dyslexia three challenges for research
Nature Reviews Neuroscience, 2015Co-Authors: Usha GoswamiAbstract:Recent years have seen the publication of a range of new theories suggesting that the basis of Dyslexia might be sensory dysfunction. In this Opinion article, the evidence for and against several prominent sensory theories of Dyslexia is closely scrutinized. Contrary to the causal claims being made, my analysis suggests that many proposed sensory deficits might result from the effects of reduced reading experience on the dyslexic brain. I therefore suggest that longitudinal studies of sensory processing, beginning in infancy, are required to successfully identify the neural basis of Developmental Dyslexia. Such studies could have a powerful impact on remediation.
-
Auditory processing interventions and Developmental Dyslexia: a comparison of phonemic and rhythmic approaches
Reading and Writing, 2013Co-Authors: Jennifer M. Thomson, Victoria Leong, Usha GoswamiAbstract:The purpose of this study was to compare the efficacy of two auditory processing interventions for Developmental Dyslexia, one based on rhythm and one based on phonetic training. Thirty-three children with Dyslexia participated and were assigned to one of three groups (a) a novel rhythmic processing intervention designed to highlight auditory rhythmic information in non-speech and speech stimuli; (b) a commercially-available phoneme discrimination intervention; and (c) a no-intervention control. The intervention lasted for 6 weeks. Both interventions yielded equivalent and significant gains on measures of phonological awareness (at both rhyme and phoneme levels), with large effect sizes at the phoneme level. Both programs had medium effect sizes on literacy outcome measures, although gains were non-significant when compared to the controls. The data suggest that rhythmic training has an important role to play in developing the phonological skills that are critical for efficient literacy acquisition. It is suggested that combining both prosodic/rhythmic and phonemic cues in auditory training programs may offer advantages for children with Developmental Dyslexia. This may be especially true for those who appear resistant to conventional phonics training methods.
-
music rhythm rise time perception and Developmental Dyslexia perception of musical meter predicts reading and phonology
Cortex, 2011Co-Authors: Martina Huss, Natasha Mead, Tim Fosker, John P Verney, Usha GoswamiAbstract:Abstract Introduction Rhythm organises musical events into patterns and forms, and rhythm perception in music is usually studied by using metrical tasks. Metrical structure also plays an organisational function in the phonology of language, via speech prosody, and there is evidence for rhythmic perceptual difficulties in Developmental Dyslexia. Here we investigate the hypothesis that the accurate perception of musical metrical structure is related to basic auditory perception of rise time, and also to phonological and literacy development in children. Methods A battery of behavioural tasks was devised to explore relations between musical metrical perception, auditory perception of amplitude envelope structure, phonological awareness (PA) and reading in a sample of 64 typically-developing children and children with Developmental Dyslexia. Results We show that individual differences in the perception of amplitude envelope rise time are linked to musical metrical sensitivity, and that musical metrical sensitivity predicts PA and reading development, accounting for over 60% of variance in reading along with age and I.Q. Even the simplest metrical task, based on a duple metrical structure, was performed significantly more poorly by the children with Dyslexia. Conclusions The accurate perception of metrical structure may be critical for phonological development and consequently for the development of literacy. Difficulties in metrical processing are associated with basic auditory rise time processing difficulties, suggesting a primary sensory impairment in Developmental Dyslexia in tracking the lower-frequency modulations in the speech envelope.
-
language universal sensory deficits in Developmental Dyslexia english spanish and chinese
Journal of Cognitive Neuroscience, 2011Co-Authors: Usha Goswami, H Sharon L Wang, Natasha Mead, Tim Fosker, Alicia De La Cruz, Martina HussAbstract:Studies in sensory neuroscience reveal the critical importance of accurate sensory perception for cognitive development. There is considerable debate concerning the possible sensory correlates of phonological processing, the primary cognitive risk factor for Developmental Dyslexia. Across languages, children with Dyslexia have a specific difficulty with the neural representation of the phonological structure of speech. The identification of a robust sensory marker of phonological difficulties would enable early identification of risk for Developmental Dyslexia and early targeted intervention. Here, we explore whether phonological processing difficulties are associated with difficulties in processing acoustic cues to speech rhythm. Speech rhythm is used across languages by infants to segment the speech stream into words and syllables. Early difficulties in perceiving auditory sensory cues to speech rhythm and prosody could lead Developmentally to impairments in phonology. We compared matched samples of children with and without Dyslexia, learning three very different spoken and written languages, English, Spanish, and Chinese. The key sensory cue measured was rate of onset of the amplitude envelope (rise time), known to be critical for the rhythmic timing of speech. Despite phonological and orthographic differences, for each language, rise time sensitivity was a significant predictor of phonological awareness, and rise time was the only consistent predictor of reading acquisition. The data support a language-universal theory of the neural basis of Developmental Dyslexia on the basis of rhythmic perception and syllable segmentation. They also suggest that novel remediation strategies on the basis of rhythm and music may offer benefits for phonological and linguistic development.
Katharina Von Kriegstein - One of the best experts on this subject based on the ideXlab platform.
-
reduced structural connectivity between left auditory thalamus and the motion sensitive planum temporale in Developmental Dyslexia
The Journal of Neuroscience, 2019Co-Authors: Nadja Tschentscher, Anja Ruisinger, Helen Blank, Begona Diaz, Katharina Von KriegsteinAbstract:Developmental Dyslexia is characterized by the inability to acquire typical reading and writing skills. Dyslexia has been frequently linked to cerebral cortex alterations; however, recent evidence also points toward sensory thalamus dysfunctions: dyslexics showed reduced responses in the left auditory thalamus (medial geniculate body, MGB) during speech processing in contrast to neurotypical readers. In addition, in the visual modality, dyslexics have reduced structural connectivity between the left visual thalamus (lateral geniculate nucleus, LGN) and V5/MT, a cerebral cortex region involved in visual movement processing. Higher LGN-V5/MT connectivity in dyslexics was associated with the faster rapid naming of letters and numbers (RANln), a measure that is highly correlated with reading proficiency. Here, we tested two hypotheses that were directly derived from these previous findings. First, we tested the hypothesis that dyslexics have reduced structural connectivity between the left MGB and the auditory-motion-sensitive part of the left planum temporale (mPT). Second, we hypothesized that the amount of left mPT–MGB connectivity correlates with dyslexics RANln scores. Using diffusion tensor imaging-based probabilistic tracking, we show that male adults with Developmental Dyslexia have reduced structural connectivity between the left MGB and the left mPT, confirming the first hypothesis. Stronger left mPT–MGB connectivity was not associated with faster RANln scores in dyslexics, but was in neurotypical readers. Our findings provide the first evidence that reduced cortico-thalamic connectivity in the auditory modality is a feature of Developmental Dyslexia and it may also affect reading-related cognitive abilities in neurotypical readers. SIGNIFICANCE STATEMENT Developmental Dyslexia is one of the most widespread learning disabilities. Although previous neuroimaging research mainly focused on pathomechanisms of Dyslexia at the cerebral cortex level, several lines of evidence suggest an atypical functioning of subcortical sensory structures. By means of diffusion tensor imaging, we here show that dyslexic male adults have reduced white matter connectivity in a cortico-thalamic auditory pathway between the left auditory motion-sensitive planum temporale and the left medial geniculate body. Connectivity strength of this pathway was associated with measures of reading fluency in neurotypical readers. This is novel evidence on the neurocognitive correlates of reading proficiency, highlighting the importance of cortico-subcortical interactions between regions involved in the processing of spectrotemporally complex sound.
-
altered structural connectivity of the left visual thalamus in Developmental Dyslexia
Current Biology, 2017Co-Authors: Christa Mulleraxt, Katharina Von Kriegstein, Alfred AnwanderAbstract:Developmental Dyslexia is a highly prevalent reading disorder affecting about 5%-10% of children [1]. It is characterized by slow and/or inaccurate word recognition skills as well as by poor spelling and decoding abilities [2]. Partly due to technical challenges with investigating subcortical sensory structures, current research on Dyslexia in humans by and large focuses on the cerebral cortex [3-7]. These studies found that Dyslexia is typically associated with functional and structural alterations of a distributed left-hemispheric cerebral cortex network (e.g., [8, 9]). However, findings from animal models and post mortem studies in humans suggest that Dyslexia might also be associated with structural alterations in subcortical sensory pathways [10-14] (reviewed in [7]). Whether these alterations also exist in Dyslexia in vivo and how they relate to Dyslexia symptoms is currently unknown. Here, we used ultra-high-resolution structural magnetic resonance imaging (MRI), diffusion MRI, and probabilistic tractography to investigate the structural connections of the visual sensory pathway in Dyslexia in vivo. We discovered that individuals with Dyslexia have reduced structural connections in the direct pathway between the left visual thalamus (lateral geniculate nucleus [LGN]) and left middle temporal area V5/MT, but not between the left LGN and left primary visual cortex. In addition, left V5/MT-LGN connectivity strength correlated with rapid naming abilities-a key deficit in Dyslexia [15]. These findings provide the first evidence of specific structural alterations in the connections between the sensory thalamus and cortex in Developmental Dyslexia. The results challenge current standard models and provide novel evidence for the importance of cortico-thalamic interactions in explaining Dyslexia.
-
dysfunction of the auditory thalamus in Developmental Dyslexia
Proceedings of the National Academy of Sciences of the United States of America, 2012Co-Authors: Begona Diaz, Florian Hintz, Stefan J Kiebel, Katharina Von KriegsteinAbstract:Developmental Dyslexia, a severe and persistent reading and spelling impairment, is characterized by difficulties in processing speech sounds (i.e., phonemes). Here, we test the hypothesis that these phonological difficulties are associated with a dysfunction of the auditory sensory thalamus, the medial geniculate body (MGB). By using functional MRI, we found that, in dyslexic adults, the MGB responded abnormally when the task required attending to phonemes compared with other speech features. No other structure in the auditory pathway showed distinct functional neural patterns between the two tasks for dyslexic and control participants. Furthermore, MGB activity correlated with Dyslexia diagnostic scores, indicating that the task modulation of the MGB is critical for performance in dyslexics. These results suggest that deficits in Dyslexia are associated with a failure of the neural mechanism that dynamically tunes MGB according to predictions from cortical areas to optimize speech processing. This view on task-related MGB dysfunction in dyslexics has the potential to reconcile influential theories of Dyslexia within a predictive coding framework of brain function.
Sylviane Valdois - One of the best experts on this subject based on the ideXlab platform.
-
Relationships between categorical perception of phonemes, phoneme awareness, and visual attention span in Developmental Dyslexia
PLOS ONE, 2016Co-Authors: Rachel Zoubrinetzky, Willy Serniclaes, Gregory Collet, Marie Ange Nguyen-morel, Sylviane ValdoisAbstract:We tested the hypothesis that the categorical perception deficit of speech sounds in Developmental Dyslexia is related to phoneme awareness skills, whereas a visual attention (VA) span deficit constitutes an independent deficit. Phoneme awareness tasks, VA span tasks and categorical perception tasks of phoneme identification and discrimination using a d/t voicing continuum were administered to 63 dyslexic children and 63 control children matched on chronological age. Results showed significant differences in categorical perception between the dyslexic and control children. Significant correlations were found between categorical perception skills, phoneme awareness and reading. Although VA span correlated with reading, no significant correlations were found between either categorical perception or phoneme awareness and VA span. Mediation analyses performed on the whole dyslexic sample suggested that the effect of categorical perception on reading might be mediated by phoneme awareness. This relationship was independent of the participants' VA span abilities. Two groups of dyslexic children with a single phoneme awareness or a single VA span deficit were then identified. The phonologically impaired group showed lower categorical perception skills than the control group but categorical perception was similar in the VA span impaired dyslexic and control children. The overall findings suggest that the link between categorical perception, phoneme awareness and reading is independent from VA span skills. These findings provide new insights on the heterogeneity of Developmental Dyslexia. They suggest that phonological processes and VA span independently affect reading acquisition.
-
the phonological and visual basis of Developmental Dyslexia in brazilian portuguese reading children
Frontiers in Psychology, 2014Co-Authors: Giseli Donadon Germano, Sylviane Valdois, Caroline Reilhac, Simone Aparecida CapelliniAbstract:Evidence from opaque languages suggests that visual attention processing abilities in addition to phonological skills may act as cognitive underpinnings of Developmental Dyslexia. We explored the role of these two cognitive abilities on reading fluency in Brazilian Portuguese, a more transparent orthography than French or English. Sixty-six children with Developmental Dyslexia and normal Brazilian Portuguese children participated. They were administered three tasks of phonological skills (phoneme identification, phoneme, and syllable blending) and three visual tasks (a letter global report task and two non-verbal tasks of visual closure and visual constancy). Results show that Brazilian Portuguese children with Developmental Dyslexia are impaired not only in phonological processing but further in visual processing. The phonological and visual processing abilities significantly and independently contribute to reading fluency in the whole population. Last, different cognitively homogeneous subtypes can be identified in the Brazilian Portuguese population of children with Developmental Dyslexia. Two subsets of children with Developmental Dyslexia were identified as having a single cognitive disorder, phonological or visual; another group exhibited a double deficit and a few children showed no visual or phonological disorder. Thus the current findings extend previous data from more opaque orthographies as French and English, in showing the importance of investigating visual processing skills in addition to phonological skills in children with Developmental Dyslexia whatever their language orthography transparency.
-
Neural dissociation of phonological and visual attention span disorders in Developmental Dyslexia: FMRI evidence from two case reports.
Brain and Language, 2012Co-Authors: Carole Peyrin, Marie Lallier, Jean-françois Démonet, Cyril Pernet, Monica Baciu, Jean François Le Bas, Sylviane ValdoisAbstract:A dissociation between phonological and visual attention (VA) span disorders has been reported in dyslexic children. This study investigates whether this cognitively-based dissociation has a neurobiological counterpart through the investigation of two cases of Developmental Dyslexia. LL showed a phonological disorder but preserved VA span whereas FG exhibited the reverse pattern. During a phonological rhyme judgement task, LL showed decreased activation of the left inferior frontal gyrus whereas this region was activated at the level of the controls in FG. Conversely, during a visual categorization task, FG demonstrated decreased activation of the parietal lobules whereas these regions were activated in LL as in the controls. These contrasted patterns of brain activation thus mirror the cognitive disorders' dissociation. These findings provide the first evidence for an association between distinct brain mechanisms and distinct cognitive deficits in Developmental Dyslexia, emphasizing the importance of taking into account the heterogeneity of the reading disorder.
-
Developmental Dyslexia the visual attention span deficit hypothesis
Cognition, 2007Co-Authors: Marie-line Bosse, Marie-josephe Tainturier, Sylviane ValdoisAbstract:The visual attention (VA) span is defined as the amount of distinct visual elements which can be processed in parallel in a multi-element array. Both recent empirical data and theoretical accounts suggest that a VA span deficit might contribute to Developmental Dyslexia, independently of a phonological disorder. In this study, this hypothesis was assessed in two large samples of French and British dyslexic children whose performance was compared to that of chronological-age matched control children. Results of the French study show that the VA span capacities account for a substantial amount of unique variance in reading, as do phonological skills. The British study replicates this finding and further reveals that the contribution of the VA span to reading performance remains even after controlling IQ, verbal fluency, vocabulary and single letter identification skills, in addition to phoneme awareness. In both studies, most dyslexic children exhibit a selective phonological or VA span disorder. Overall, these findings support a multi-factorial view of Developmental Dyslexia. In many cases, Developmental reading disorders do not seem to be due to phonological disorders. We propose that a VA span deficit is a likely alternative underlying cognitive deficit in Dyslexia.
-
The Cognitive Deficits Responsible for Developmental Dyslexia: Review of Evidence for a Selective Visual Attentional Disorder.
Dyslexia (Chichester England), 2004Co-Authors: Sylviane Valdois, Marie-line Bosse, Marie-josephe TainturierAbstract:There is strong converging evidence suggesting that Developmental Dyslexia stems from a phonological processing deficit. However, this hypothesis has been challenged by the widely admitted heterogeneity of the dyslexic population, and by several reports of dyslexic individuals with no apparent phonological deficit. In this paper, we discuss the hypothesis that a phonological deficit may not be the only core deficit in Developmental Dyslexia and critically examine several alternative proposals. To establish that a given cognitive deficit is causally related to Dyslexia, at least two conditions need to be fulfilled. First, the hypothesized deficit needs to be associated with Developmental Dyslexia independently of additional phonological deficits. Second, the hypothesized deficit must predict reading ability, on both empirical and theoretical grounds. While most current hypotheses fail to fulfil these criteria, we argue that the visual attentional deficit hypothesis does. Recent studies providing evidence for the independence of phonological and visual attentional deficits in Developmental Dyslexia are reviewed together with empirical data showing that phonological and visual attentional processing skills contribute independently to reading performance. A theoretical model of reading is outlined in support of a causal link between a visual attentional disorder and a failure in reading acquisition. Copyright © 2004 John Wiley & Sons, Ltd.
Jingjing Zhao - One of the best experts on this subject based on the ideXlab platform.
-
visual attention span and phonological skills in chinese Developmental Dyslexia
Research in Developmental Disabilities, 2021Co-Authors: Chen Cheng, Yue Yao, Zhengjun Wang, Jingjing ZhaoAbstract:Abstract Background It has been debated whether visual attention span deficit was independent from phonological deficit in alphabetic Developmental Dyslexia. Yet, this issue has never been examined in Chinese Developmental Dyslexia. Aim The aim of the present study was to concurrently investigate visual attention span deficit and phonological deficit in Chinese Developmental Dyslexia, and examine the relationship between them. Methods A total of 45 Chinese dyslexic and 43 control children aged between 8 and 11 years old participated in this study. A visual one-back paradigm with both verbal stimuli (character and digit strings) and nonverbal stimuli (color dots and symbols) was employed for measuring visual attention span. Phonological skills were measured by three dimensions: phonological awareness, rapid automatized naming, and verbal short-term memory. Results Chinese dyslexic children showed deficits in verbal visual attention span and all three dimensions of phonological skills, but not in nonverbal visual attention span. Phonological skills significantly contributed to explaining variance of reading skills and classifying dyslexic and control memberships. Almost all Chinese dyslexic participants who showed a deficit in visual attention span also showed a phonological deficit. Conclusion The study suggests that visual attention span deficit is not independent from phonological deficit in Chinese Developmental Dyslexia.
-
neuroanatomy of Developmental Dyslexia pitfalls and promise
Neuroscience & Biobehavioral Reviews, 2018Co-Authors: Franck Ramus, Jingjing Zhao, Irene Altarelli, Katarzyna Jednorog, Lou Scotto Di CovellaAbstract:Abstract Investigations into the neuroanatomical bases of Developmental Dyslexia have now spanned more than 40 years, starting with the post-mortem examination of a few individual brains in the 60s and 70s, and exploding in the 90s with the widespread use of MRI. The time is now ripe to reappraise the considerable amount of data gathered with MRI using different types of sequences (T1, diffusion, spectroscopy) and analysed using different methods (manual, voxel-based or surface-based morphometry, fractional anisotropy and tractography, multivariate analyses…). While selective reviews of mostly small-scale studies seem to provide a coherent view of the brain disruptions that are typical of Dyslexia, involving left perisylvian and occipito-temporal regions, we argue that this view may be deceptive and that meta-analyses and large-scale studies rather highlight many inconsistencies and limitations. We discuss problems inherent to small sample size as well as methodological difficulties that still undermine the discovery of reliable neuroanatomical bases of Dyslexia, and we outline some recommendations to further improve this research area.
Sukman Tsang - One of the best experts on this subject based on the ideXlab platform.
-
in search of subtypes of chinese Developmental Dyslexia
Journal of Experimental Child Psychology, 2007Co-Authors: David W. Chan, Sukhan Lee, Kevin K Chung, Sukman TsangAbstract:The dual-route model offers a popular way to classify Developmental Dyslexia into phonological and surface subtypes. The current study examined whether this dual-route model could provide a framework for understanding the varieties of Chinese Developmental Dyslexia. Three groups of Chinese children (dyslexics, chronological-age controls, and reading-level controls) were tested on Chinese exception character reading, pseudocharacter reading (analogous to English nonword reading), novel word learning, and some phonological and orthographic skills. It was found that Chinese exception character reading and pseudocharacter reading were highly correlated and that orthographic skills was a better predictor of both Chinese exception character and pseudocharacter reading than was phonological skills. More than half (62%) of the children in the Dyslexia sample were classified as belonging to the surface subtype, but no children were classified as belonging to the phonological subtype. These results suggested that the lexical and sublexical routes in Chinese are highly interdependent or that there may be only one route from print to speech as suggested by the connectionist models. Chinese dyslexic children generally are characterized as having delays in various phonological and orthographic skills, but some, such as those identified as surface dyslexics in the current study, are more severely impaired.
-
cognitive profiling and preliminary subtyping in chinese Developmental Dyslexia
Cognition, 2004Co-Authors: David W. Chan, Sukman Tsang, Sukhan Lee, Vivian Hui LuanAbstract:The present study examined the cognitive profile and subtypes of Developmental Dyslexia in a nonalphabetic script, Chinese. One hundred and forty-seven Chinese primary school children with Developmental Dyslexia were tested on a number of literacy and cognitive tasks. The results showed that rapid naming deficit and orthographic deficit were the two most dominant types of cognitive deficits in Chinese Developmental Dyslexia, and that rapid naming and orthographic processing had significant unique contributions to literacy performance. Seven subtypes of Dyslexia--global deficit, orthographic deficit, phonological memory deficit, mild difficulty, and three other subtypes with rapid-naming-related deficits--were identified using scores of the cognitive tasks as classification measures in cluster analyses. These subtypes were validated with a behaviour checklist and three literacy measures. The authors suggested that orthographic and rapid naming deficits in Chinese dyslexic children might pose an interrelated problem in developing orthographic knowledge and representation. Therefore, orthographic-related difficulties may be the crux of the problem in Chinese Developmental Dyslexia.
-
the cognitive profile and multiple deficit hypothesis in chinese Developmental Dyslexia
Developmental Psychology, 2002Co-Authors: Connie Sukhan Ho, David W. Chan, Sukman TsangAbstract:: The present study was conducted to examine the cognitive profile and multiple-deficit hypothesis in Chinese Developmental Dyslexia. Thirty Chinese dyslexic children in Hong Kong were compared with 30 average readers of the same chronological age (CA controls) and 30 average readers of the same reading level (RL controls) in a number of rapid naming, visual, phonological, and orthographic tasks. Chinese dyslexic children performed significantly worse than the CA controls but similarly to the RL controls on most of the cognitive tasks. The rapid naming deficit was found to be the most dominant type of cognitive deficit in Chinese dyslexic children. Over half of the dyslexic children exhibited deficits in 3 or more cognitive areas, and there was a significant association between the number of cognitive deficits and the degree of reading and spelling impairment. The present findings support the multiple-deficit hypothesis in Chinese Developmental Dyslexia.
