Recovery in reading: A treatment study of acquired deep dyslexia in Spanish

Background: Adult oral reading in consistent orthographies, like Spanish, is argued to proceed through sublexical spelling-to-sound conversion. Hence, it was surprising that Davies and Cuetos (2005 Davies, R. and Cuetos, F. 2005. Acquired dyslexia in Spanish: A review and some observations on a new case of deep dyslexia. Behavioural Neurology,, 16: 85–101. [PubMed], [Web of Science ®] , [Google Scholar]) observed a Spanish-speaking aphasic patient, MJ, who showed some capacity to read words aloud—producing many semantic errors—alongside an inability to read nonwords. MJ's symptoms are congruent with deep dyslexia. We investigated whether her reading could be improved through therapy addressing those deep dyslexic symptoms (de Partz, 1986 de Partz, M-P. 1986. Re-education of a deep dyslexic patient: Rationale of the method and results. Cognitive Neuropsychology,, 3: 149–177. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]).

Aims: We expected to see joint improvement in word and nonword reading if therapy aimed at facilitating improvement in nonword reading succeeded, due to the consistency of the orthography. We hypothesised that occurrence of semantic paralexias in reading should decrease as reading skills improved. Alternatively, if therapy had led to the establishment of a lexical-semantic reading strategy not available to the patient before injury, then we anticipated the possibility that semantic errors could actually increase in occurrence as more therapy was received over time.

Methods & Procedures: Our study began 18 months after MJ's brain injury, and continued over 2 years. Training was given in completing spelling–sound mappings at the level of grapheme–phoneme correspondences, syllables and words, in phoneme awareness and the combination of phonemes, and in word–picture association. We tested oral reading with the same word and nonword stimuli at four time points through the period of our investigation. We analysed accuracy and error types.

Outcomes & Results: By the end of our investigation, MJ presented near-normal word reading and greatly improved, though still impaired, nonword reading. Production of semantic errors disappeared. Thus, adding to some previous case studies (Friedman, 1996 Friedman, R. B. 1996. Recovery from deep alexia to phonological alexia: Points on a continuum. Brain and Language,, 52: 114–128. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), our patient's symptoms evolved from those typical of deep dyslexia to those typical of phonological dyslexia.

Conclusions: Our findings show that, even in a language with a transparent orthography, readers can be aided by therapy addressing both lexical and non-lexical reading. The implication is that premorbid reading in a transparent orthography may depend on lexical and non-lexical reading. This conclusion is supported by the superior improvement of word compared to nonword reading, and by the decline in production of semantic paralexias accompanying the improvement in reading performance.     

Implicit phonological and semantic processing in children with developmental dyslexia: Evidence from event-related potentials

Dyslexia is characterized by a core phonological deficit, although recent studies indicate that semantic impairment also contributes to this condition. In this study, event-related potentials (ERP) were used to examine whether the N400 wave in dyslexic children is modulated by phonological or semantic priming, similarly to age-matched controls. ERPs were recorded while children listened to word lists in which the semantic and phonological congruency of the terminal words were manipulated. No overt judgments were made by participants. In control children the N400 amplitude to both semantically and phonologically incongruent words was enlarged relative to congruent words. Dyslexic children exhibited a dissociation of priming effects depending on whether semantic or phonological primes were used. Semantic priming elicited an N400 effect comparable to controls, though delayed. In phonological priming, the dyslexics differed from controls in both the phonologically incongruent and congruent conditions showing reduced N400 amplitude in the former and enhanced N400 in the latter. This pattern suggests that when faced with phonological priming, dyslexics show abnormal neural responses related to both integration of similarities between the consecutive stimuli and the ability to detect incongruent stimuli. Semantic priming seems relatively intact in dyslexics, however neural responses to contextual incongruency are delayed.     

Orthographic connectivity in Arabic reading: a case study of an individual with deep dyslexia and letter-by-letter reading

ABSTRACT

Arabic orthography is complex, partly as a consequence of variations in orthographic connectivity. In this article, we present the case study of CHS, an Arabic individual with deep dyslexia associated with letter-by-letter reading. In the experimental study, we specifically explored the influence of orthographic connectivity on CHS’s word recognition and reading abilities. Our results show that CHS’s performance was better preserved for words and non-words made up of connected letters than made up of non-connected letters. CHS demonstrated impairment of visuoperceptual mechanisms, which affected the processing of complex orthographic material. These results provide insight into the cognitive processes associated with reading Arabic.     

More evidence for a continuum between phonological and deep dyslexia: Novel data from three measures of direct orthography-to-phonology translation

Background: Over recent years a number of studies have suggested that phonological and deep dyslexia are not separate acquired dyslexias but actually reflect different points along a single continuum. Behaviourally this continuum was originally defined in terms of the graded presence/absence of the “symptoms” of deep dyslexia.

Aims: Given that orthography → phonology translation is core to phonological-deep dyslexia, it becomes critical to measure the degree and nature of any such direct phonological activation in these patients. Nonword reading accuracy has been the most commonly used measure of the status of direct orthographic → phonological activation but this measure can floor out in many phonological-deep dyslexic patients. In such circumstances, however, researchers have found evidence for some residual O→P function using reading tasks that do not require overt production—and these tasks might provide an important set of additional measures to test for a gradation of performance at the severer end of the phonological-deep dyslexic continuum.

Methods & Procedures: In the present study three tasks of this type (spoken-to-written nonword-matching, a novel word-matching task, and pseudohomophone reading) were developed and tested in a case-series of phonological-deep dyslexia (and made available in the appendices to this paper).

Outcomes & Results: As suggested from past studies, even patients with severely impaired overt nonword reading exhibited above-chance performance on the matching task and a pseudohomophone effect. The accuracy on these tasks varied in a graded manner across the case-series.

Conclusions: Two factors are key to this dyslexia continuum: the severity of phonological impairment and also the degree of interaction between semantic and impaired phonological representations, indicating that semantic representations become more central to reading in the face of phonological impairment.     

发展性阅读障碍的脑功能成像研究

总结了认知神经科学对拼音文字中发展性阅读障碍的脑功能成像 (fMRI和PET)研究 ,指出这些研究反映了解释发展性阅读障碍的两种理论倾向———强调语言模块化的语音加工缺陷假说和强调非语言学作用的基本知觉加工缺陷假说。研究表明 ,颞 顶联合区 (角回及其周围脑区 )功能活动的变异是阅读障碍的主要神经基础 ,但其他脑区也起一定的作用。作者认为 ,由于汉语文字系统的独特性 ,开展中文发展性阅读障碍的脑功能成像研究是摆在认知神经科学家面前的任务之一。     

When all hypotheses are right: A multifocal account of dyslexia

Many hypotheses have been proposed about the brain underpinnings of developmental dyslexia, but none of them accommodates the variable deficits observed. To address the issue of anatomical deficits in dyslexia; total and partial volumes, lateralization indices (LI), and local gray matter volumes (LGMV) were measured. Analyses were performed in large samples of control and dyslexic subjects, and in correlation with their performance on phonological, reading, and spelling tests. Results indicate an absence of net differences in terms of volumes but significant continuities and discontinuities between groups in their correlations between LI, LGMV, and performances. Structural connectivity also highlighted correlations between areas showing (dis)continuities between control and dyslexic subjects. Overall, our data put forward the idea of a multifocal brain abnormalities in dyslexia with a major implication of the left superior temporal gyrus, occipital‐temporal cortices, and lateral/medial cerebellum, which could account for the diverse deficits predicted by the different theories. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

Large-scale neural correlates of developmental dyslexia

Abstract. Recent work in the field of developmental dyslexia has emphasized the large-scale neural aspects of the disorder as measured by means of contemporary imaging techniques, electrophysiology, and post-mortem analyses. This article presents findings from these research domains and comprehensively reviews their relevance with respect to the behavioral and cognitive profiles of dyslexia. Large-scale alterations were observed in the perisylvian region across paradigms. Convergent evidence has also been reported in terms of hemispheric balance. Specifically, deviances in cerebral asymmetry associated with atypical organization of the left hemisphere were found in both children and adults with dyslexia. Emerging research encompassing high-temporal resolution methods such as magnetoencephalography (MEG) suggests right-hemisphere involvement and points to the complexity of the developmental disorder. A combined approach of structural imaging and MEG, and most importantly theory driven behavioral tasks may shed light on dynamics and trajectories of the neurobiology of dyslexia.     

Priming of strong semantic relations in the left and right visual fields: a time-course investigation

Prior time-course investigations of cerebral asymmetries in word processing have sometimes reported hemisphere differences in the onset and duration of semantic priming. In the current study, very strongly related word pairs (categorical associates such as arm-leg) were employed in a low relatedness proportion lexical decision priming paradigm. A range of prime-target stimulus onset asynchronies (SOAs: 150-800 ms) was included. Only very weak evidence was obtained for a LVF priming lag at the briefest SOA, while priming was bilateral at moderately long SOAs. We consider these data in the context of previous time-course studies and suggest that, when highly semantically similar word pairs are used, a right hemisphere priming lag is, at best, a very small effect.     

Fractionating the multi-character processing deficit in developmental dyslexia: Evidence from two case studies

While there is growing evidence that some dyslexic children suffer from a deficit in simultaneously processing multiple visually displayed elements, the precise nature of the deficit remains largely unclear. The aim of the present study is to investigate possible cognitive impairments at the source of this deficit in dyslexic children. The visual processing of simultaneously presented letters was thus thoroughly assessed in two dyslexic children by means of a task that requires the report of briefly presented multi-letters arrays. A computational model of the attentional involvement in multi-object recognition ( [Bundesen, 1990] and [Bundesen, 1998]) served as framework for analysing the data. By combining psychophysical measurements with computational modelling, we demonstrated that the visual processing deficit of simultaneously displayed letters, observed in the two dyslexic individuals reported in the current study, stems from at least two distinct cognitive sources: a reduction of the rate of—letter—information uptake, and a limitation of the maximal number of elements extracted from a brief visual display and stored in visual short-term memory. Possible relations between these impairments and learning to read proficiently are discussed.     

Disrupted white matter connectivity underlying developmental dyslexia: A machine learning approach

Developmental dyslexia has been hypothesized to result from multiple causes and exhibit multiple manifestations, implying a distributed multidimensional effect on human brain. The disruption of specific white‐matter (WM) tracts/regions has been observed in dyslexic children. However, it remains unknown if developmental dyslexia affects the human brain WM in a multidimensional manner. Being a natural tool for evaluating this hypothesis, the multivariate machine learning approach was applied in this study to compare 28 school‐aged dyslexic children with 33 age‐matched controls. Structural magnetic resonance imaging (MRI) and diffusion tensor imaging were acquired to extract five multitype WM features at a regional level: white matter volume, fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. A linear support vector machine (LSVM) classifier achieved an accuracy of 83.61% using these MRI features to distinguish dyslexic children from controls. Notably, the most discriminative features that contributed to the classification were primarily associated with WM regions within the putative reading network/system (e.g., the superior longitudinal fasciculus, inferior fronto‐occipital fasciculus, thalamocortical projections, and corpus callosum), the limbic system (e.g., the cingulum and fornix), and the motor system (e.g., the cerebellar peduncle, corona radiata, and corticospinal tract). These results were well replicated using a logistic regression classifier. These findings provided direct evidence supporting a multidimensional effect of developmental dyslexia on WM connectivity of human brain, and highlighted the involvement of WM tracts/regions beyond the well‐recognized reading system in dyslexia. Finally, the discriminating results demonstrated a potential of WM neuroimaging features as imaging markers for identifying dyslexic individuals. Hum Brain Mapp 37:1443‐1458, 2016. © 2016 Wiley Periodicals, Inc.     

Sub-types of deep dyslexia: a case study of central deep dyslexia

A case study is reported of a female patient (JAH), who following a left middle cerebral artery infarct, presented with the cardinal symptoms of deep dyslexia and deep dysphasia (semantic errors when reading and repeating words aloud, respectively). Detailed assessment revealed impaired performance across modalities for many tasks, but particularly those tasks that depend on an intact store of semantic knowledge. Her acquired dyslexia is best characterised as deep dyslexia of a central sub-type.     

Jargon dyslexia: A single case study of intact reading comprehension in a jargon dysphasic

Abstract

In this single case study, we investigated the reading skills of a patient with a florid phonemic jargon dysphasia. The patient's speech perception and language comprehension were profoundly impaired. By contrast, his reading was relatively spared. Specifically, his comprehension of single written words appeared to be intact, including those words that he misread. His reading aloud, although far superior to his ability to name to confrontation, was characterized by phonemic errors, many of which were perseverations from his previous responses. His reading accuracy was not affected by rates of presentation and temporal factors did not appear to influence the number of these perseverative responses. His dyslexic difficulties are attributed to a failure of normal inhibitory processes.     

Cytoarchitectonic abnormalities in developmental dyslexia: A case study

A patient is reported who had a well-documented history of developmental dyslexia. Reading difficulties were present in other male members of the immediate family. Gross anatomical and cytoarchitectonic analysis of the brain in serial sections showed a consistently wider left cerebral hemisphere, an area of polymicrogyria in the left temporal speech region, and mild cortical dysplasias in limbic, primary, and association cortices of the left hemisphere.     

Planum temporale asymmetry in developmental dyslexia: Revisiting an old question

Among the various asymmetrical structures of the human brain, the planum temporale, an anatomical region associated with a variety of auditory and language‐related processes, has received particular attention. While its surface area has been shown to be greater in the left hemisphere compared to the right in about two‐thirds of the general population, altered patterns of asymmetry were revealed by post mortem analyses in individuals with developmental dyslexia. These findings have been inconsistently replicated in magnetic resonance imaging studies of this disorder. In this report, we attempt to resolve past inconsistencies by analyzing the T1‐weighted MR images of 81 children (mean age: 11 years, sd: 17 months), including 46 control (25 boys) and 35 dyslexic children (20 boys). We manually outlined Heschl's gyri, the planum temporale and the posterior rami of the Sylvian fissure on participants' brain images, using the same anatomical criteria as in post mortem studies. Results revealed an altered pattern of asymmetry of the planum temporale surface area in dyslexic boys only, with a greater proportion of rightward asymmetrical cases among dyslexic boys compared to control boys. Additionally, analyses of cortical thickness showed no asymmetry differences between groups for any of the regions of interest. Finally, a greater number of Heschl's gyrus full duplications emerged for the right hemisphere of dyslexic boys compared to controls. The present findings confirm and extend early post mortem observations. They also stress the importance of taking gender into account in studies of developmental dyslexia. Hum Brain Mapp 35:5717–5735, 2014. © 2014 Wiley Periodicals, Inc.     

Neural correlates of sequence learning in children with developmental dyslexia

Developmental Dyslexia (DD) is a condition in which reading accuracy and/or fluency falls substantially below what is expected based on the individuals age, general level of cognitive ability, and educational opportunities. The procedural circuit deficit hypothesis (PDH) proposes that DD may be largely explained in terms of alterations of the cortico‐basal ganglia procedural memory system (in particular of the striatum) whereas the (hippocampus‐dependent) declarative memory system is intact, and may serve a compensatory role in the condition. The present study was designed to test this hypothesis. Using Magnetic Resonance Imaging, we examined the functional and structural brain correlates of sequence‐specific procedural learning (SL) on the serial reaction time task, in 17 children with DD and 18 typically developing (TD) children. The study was performed over 2 days with a 24‐h interval between sessions. In line with the PDH, the DD group showed less activation of the striatum during the processing of sequential statistical regularities. These alterations predicted the amount of SL at day 2, which in turn explained variance in children''s reading fluency. Additionally, reduced hippocampal activation predicted larger SL gains between day 1 and day 2 in the TD group, but not in the DD group. At the structural level, caudate nucleus volume predicted the amount of acquired SL at day 2 in the TD group, but not in the DD group. The findings encourage further research into factors that promote learning in children with DD, including through compensatory mechanisms.     

Automated identification of ERP peaks through Dynamic Time Warping: An application to developmental dyslexia

ObjectiveThis article proposes a method to automatically identify and label event-related potential (ERP) components with high accuracy and precision.MethodsWe present a framework, referred to as peak-picking Dynamic Time Warping (ppDTW), where a priori knowledge about the ERPs under investigation is used to define a reference signal. We developed a combination of peak-picking and Dynamic Time Warping (DTW) that makes the temporal intervals for peak-picking adaptive on the basis of the morphology of the data. We tested the procedure on experimental data recorded from a control group and from children diagnosed with developmental dyslexia.ResultsWe compared our results with the traditional peak-picking. We demonstrated that our method achieves better performance than peak-picking, with an overall precision, recall and F-score of 93%, 86% and 89%, respectively, versus 93%, 80% and 85% achieved by peak-picking.ConclusionWe showed that our hybrid method outperforms peak-picking, when dealing with data involving several peaks of interest.SignificanceThe proposed method can reliably identify and label ERP components in challenging event-related recordings, thus assisting the clinician in an objective assessment of amplitudes and latencies of peaks of clinical interest.     

Slow perceptual processing at the core of developmental dyslexia: a parameter-based assessment of visual attention

The cognitive causes as well as the neurological and genetic basis of developmental dyslexia, a complex disorder of written language acquisition, are intensely discussed with regard to multiple-deficit models. Accumulating evidence has revealed dyslexics’ impairments in a variety of tasks requiring visual attention. The heterogeneity of these experimental results, however, points to the need for measures that are sufficiently sensitive to differentiate between impaired and preserved attentional components within a unified framework. This first parameter-based group study of attentional components in developmental dyslexia addresses potentially altered attentional components that have recently been associated with parietal dysfunctions in dyslexia. We aimed to isolate the general attentional resources that might underlie reduced span performance, i.e., either a deficient working memory storage capacity, or a slowing in visual perceptual processing speed, or both. Furthermore, by analysing attentional selectivity in dyslexia, we addressed a potential lateralized abnormality of visual attention, i.e., a previously suggested rightward spatial deviation compared to normal readers. We investigated a group of high-achieving young adults with persisting dyslexia and matched normal readers in an experimental whole report and a partial report of briefly presented letter arrays. Possible deviations in the parametric values of the dyslexic compared to the control group were taken as markers for the underlying deficit.The dyslexic group showed a striking reduction in perceptual processing speed (by 26% compared to controls) while their working memory storage capacity was in the normal range. In addition, a spatial deviation of attentional weighting compared to the control group was confirmed in dyslexic readers, which was larger in participants with a more severe dyslexic disorder. In general, the present study supports the relevance of perceptual processing speed in disorders of written language acquisition and demonstrates that the parametric assessment provides a suitable tool for specifying the underlying deficit within a unitary framework.     

Dissociation in the recovery from neglect dyslexia and visuospatial unilateral neglect: a case report

The recovery of the ability to read of a patient affected by persistent visuospatial neglect suggests the functional independence of the two phenomena. Neglect dyslexia seems to be an example of a dissociation between an implicit and explicit knowledge of the characteristics of the stimulus.

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Sommario Il recupero della capacità di lettura in un paziente con persistente neglect visuo-spaziale suggerisce l'indipendenza funzionale dei due fenomeni. La neglect dyslexia sembra costituire un esempio di dissociazione tra conoscenza implicita ed esplicita delle caratteristiche dello stimolo.

     

Neglect dyslexia: A matter of “good looking”

Brain-damaged patients with right-sided unilateral spatial neglect (USN) often make left-sided errors in reading single words or pseudowords (neglect dyslexia, ND). We propose that both left neglect and low fixation accuracy account for reading errors in neglect dyslexia.