A temporal sampling framework for developmental dyslexia

Neural coding by brain oscillations is a major focus in neuroscience, with important implications for dyslexia research. Here, I argue that an oscillatory 'temporal sampling' framework enables diverse data from developmental dyslexia to be drawn into an integrated theoretical framework. The core deficit in dyslexia is phonological. Temporal sampling of speech by neuroelectric oscillations that encode incoming information at different frequencies could explain the perceptual and phonological difficulties with syllables, rhymes and phonemes found in individuals with dyslexia. A conceptual framework based on oscillations that entrain to sensory input also has implications for other sensory theories of dyslexia, offering opportunities for integrating a diverse and confusing experimental literature.     

The Continuum of Deep/Surface Dyslexia

A right-handed male sustained traumatic brain injury which resulted in anomia, dyslexia, and agraphia. The most severe CT (computed tomography)-identified brain damage was located in the right parieto-temporal lobe. In the first months following the injury, the pattern of reading errors was similar to that associated with deep dyslexia. However, nonlexical derivation of phonology from print was not abolished. As the patient's ability to associate letter patterns with sounds improved, oral reading also improved. Although he no longer produced semantic errors in oral reading, he continued to produce oral reading errors that were visually and phonologically related to the targets. Four months after the injury, the error pattern observed in the patient's oral reading was consistent with very mild surface dyslexia. The significance of these observations to dual-deficit models of acquired dyslexia is discussed, as are their implications for rehabilitation.     

Writing problems in developmental dyslexia: under-recognized and under-treated

The International Dyslexia Association defines dyslexia as unexpected problems of neurobiological origin in accuracy and rate of oral reading of single real words, single pseudowords, or text or of written spelling. However, prior research has focused more on the reading than the spelling problems of students with dyslexia. A test battery was administered to 122 children who met the inclusion criteria for dyslexia and qualified their families for participation in a family genetics study that has been ongoing for over a decade. Their parents completed the same test battery. Although a past structural equation modeling study of typically developing children identified a significant path from handwriting to composition quality, the current structural equation modeling study identified a significant path from spelling to composition for children and their parents with dyslexia. Grapho-motor planning did not contribute uniquely to their composition, showing that writing is not just a motor skill. Students with dyslexia do have a problem in automatic letter writing and naming, which was related to impaired inhibition and verbal fluency and may explain their spelling problems. Results are discussed in reference to the importance of providing explicit instruction in the phonological, orthographic, and morphological processes of spelling and in composition to students with dyslexia and not only offering accommodation for their writing problems.     

发展性阅读障碍的遗传关联分析

发展性阅读障碍是一种遗传性很高的认知功能缺陷, 运用关联分析对其遗传机制进行研究是近年来的新趋势。从研究方法的视角可以将现有的关联分析研究归为以下三类：家系法研究、病例-控制法研究和数量性状关联分析研究。阅读障碍关联分析研究的新趋势主要体现在与全基因组扫描技术、神经成像技术以及基因功能研究的结合上, 促进了从“基因-大脑-行为”层面对发展性阅读障碍的遗传机制进行理解。     

Picture naming deficits in developmental dyslexia in German

Recent research with English developmental dyslexics comparing the picture naming performance of these children to the picture naming performance of non-dyslexic (‘garden variety’) poor readers, reading age matched controls and chronological age matched controls has suggested that a selective difficulty in retrieving the phonological codes of known names on demand underlies the picture naming deficit found in developmental dyslexia (Swan & Goswami, Picture naming deficits in developmental dyslexia: the phonological representations hypothesis, Brain and Language, 56 (1997), 334–353). If the underlying causal factors in dyslexia are independent of the orthography that the child is learning to read, then a difficulty in retrieving the phonological codes of known names on demand should also be found in developmental dyslexics who are learning to read other languages. We therefore set out to replicate Swan and Goswami’s study with a group of German developmental dyslexics. We were interested to see whether a phonological deficit is characteristic of dyslexia in all orthographies, even those, such as German, in which high orthographic transparency means that dyslexic children read with considerable accuracy.     

Bilinguals who stutter: A cognitive perspective

PurposeBrain differences, both in structure and executive functioning, have been found in both developmental stuttering and bilingualism. However, the etiology of stuttering remains unknown. The early suggestion that stuttering is a result of brain dysfunction has since received support from various behavioral and neuroimaging studies that have revealed functional and structural brain changes in monolinguals who stutter (MWS). In addition, MWS appear to show deficits in executive control. However, there is a lack of data on bilinguals who stutter (BWS). This literature review is intended to provide an overview of both stuttering and bilingualism as well as synthesize areas of overlap among both lines of research and highlight knowledge gaps in the current literature.MethodsA systematic literature review on both stuttering and bilingualism studies was conducted, searching for articles containing “stuttering” and/or “bilingualism” and either “brain”, “executive functions”, “executive control”, “motor control”, “cognitive reserve”, or “brain reserve” in the PubMed database. Additional studies were found by examining the reference list of studies that met the inclusion criteria.ResultsA total of 148 references that met the criteria for inclusion in this paper were used in the review. A comparison of the impact of stuttering or bilingualism on the brain are discussed.ConclusionPrevious research examining a potential bilingual advantage for BWS is mixed. However, if such an advantage does exist, it appears to offset potential deficits in executive functioning that may be associated with stuttering.     

Reasoning and dyslexia: A spatial strategy may impede reasoning with visually rich information

Bacon, Handley and Newstead (2003, 2004) , have presented evidence for individual differences in reasoning strategies, with most people seeming to represent and manipulate problem information using either a verbal or a spatial strategy. There is also evidence that individuals with dyslexia are inclined to conceptualise information in a visuo‐spatial, rather than a verbal, way (e.g. von Károlyi et al., 2003 ). If so, we might expect a higher proportion of individuals with dyslexia to be spatial reasoners, compared with individuals who do not have dyslexia. The study reported here directly compared strategies reported by these two groups of participants on a syllogistic reasoning task. Moreover, problem content was manipulated so that reasoning across concrete and abstract materials could be compared. The findings suggest that whilst most individuals without dyslexia use a verbal strategy, reasoners with dyslexia do tend to adopt a spatial approach, though their performance is impaired with visually concrete materials. However, when reasoning with more abstract content, they perform comparably with non‐dyslexic controls. The paper discusses these results in the light of recent research which has suggested that visual images may impede reasoning, and considers how individuals with dyslexia may differ from other reasoners.     

Do differences in brain activation challenge universal theories of dyslexia?

It has been commonly agreed that developmental dyslexia in different languages has a common biological origin: a dysfunction of left posterior temporal brain regions dealing with phonological processes. Siok, Perfetti, Jin, and Tan (2004, Nature, 431, 71-76) challenge this biological unity theory of dyslexia: Chinese dyslexics show no deficits in posterior temporal brain regions but a functional disruption of the left middle frontal gyrus. Here, I will argue that these data do not challenge universal cognitive theories of dyslexia according to which weaknesses in the ability to process the phonological features of language are at the origin of dyslexia.     

Working memory functioning in developmental dyslexia

Working memory impairments in dyslexia are well documented. However, research has mostly been limited to the phonological domain, a modality in which people with dyslexia have a range of problems. In this paper, 22 adult students with dyslexia and 22 age- and IQ-matched controls were presented with both verbal and visuospatial working memory tasks. Performance was compared on measures of simple span, complex span (requiring both storage and processing), and dynamic memory updating in the two domains. The dyslexic group had significantly lower spans than the controls on all the verbal tasks, both simple and complex, and also on the spatial complex span measure. Impairments remained on the complex span measures after controlling statistically for simple span performance, suggesting a central executive impairment in dyslexia. The novelty of task demands on the initial trials of the spatial updating task also proved more problematic for the dyslexic than control participants. The results are interpreted in terms of extant theories of dyslexia. The possibility of a supervisory attentional system deficit in dyslexia is also raised. It seems clear that working memory difficulties in dyslexia extend into adulthood, can affect performance in both the phonological and visuospatial modalities, and implicate central executive dysfunction, in addition to problems with storage.     

发展性阅读障碍与脑异常的因果关系:研究范式及发现

关于阅读障碍神经机制的研究已经有很多,但到目前为止,研究者仍不完全清楚,阅读障碍者脑区的异常,究竟是阅读障碍的原因还是结果。研究者发展出不同的研究范式来探究此问题,包括学龄前研究、双对照组研究、纵向研究等。文中综述了这些研究范式各具的优势、不足和研究结果之间的一致性,并分析了确认因果关系之所以困难的原因。在此基础上,提出如下建议：（1）细致区分阅读障碍的亚类型;（2）以成熟和完善的阅读认知-神经模型为指导;（3）通过不同的研究范式进行交叉印证;（4）综合考虑脑的动态发展变化特点,和基因、环境、经验的作用等多种因素的影响。     

发展性阅读障碍语音缺陷的脑科学研究及对阅读教学的启示

阅读障碍语音缺陷是阅读障碍的关键原因之一。脑科学研究发现,拼音文字系统中阅读障碍者在语音加工的神经机制上存在缺陷,相关脑区包括颞—顶—枕联合区和额下回;而汉语阅读障碍者语音加工时,激活的脑区和拼音文字系统阅读障碍者激活的脑区不同,涉及左额中回和右脑一些皮层。基于此,提出了相应的阅读教学建议。     

阅读障碍儿童的形音捆绑缺陷及其脑神经机制

形音捆绑缺陷研究是国内外阅读障碍研究领域的一个新方向。本文阐述了形音捆绑加工的理论与定义,综述了国内外研究者经常采用的三种形音捆绑的研究范式:配对联想学习、变化检测范式和线索回忆任务,介绍并分析了各研究范式的优缺点、适用范围及主要研究发现。同时,综述与评价了国内外有关阅读障碍形音捆绑缺陷的脑机制研究的主要结论及不足。最后,本文讨论了现有研究在实验设计和理论上的贡献与不足,提出了今后的研究方向和改进建议。     

发展性阅读障碍的生理基础

发展性阅读障碍是关系人类健康和发展的重要课题,对其产生机制的探讨有利于寻找适当的治疗方法.文章在简要回顾阅读障碍的界定、研究内容和有关理论争论基础上,重点介绍了阅读障碍的神经基础和遗传机制.文章从大脑结构和功能单侧化、完成认知任务时大脑的激活模式、激活时间进程以及视觉巨细胞等方面介绍了发展性阅读障碍者与正常读者之间存在的差异.文章还指出许多双生子研究都发现同孪双生子的阅读障碍同现率高于异孪双生子,尤其是近期的遗传学研究鉴定出几个与阅读障碍有关的染色体,如6号和15号染色体与语音障碍和拼写障碍有关.这些研究结果说明发展性阅读障碍有一定的脑神经基础和遗传基础.     

Towards modern post-coma care based on neuroscientific evidence

BackgroundUnderstanding the mechanisms underlying human consciousness is pivotal to improve the prognostication and treatment of severely brain-injured patients. Consciousness remains an elusive concept and the identification of its neural correlates is an active subject of research, however recent neuroscientific advances have allowed scientists to better characterize disorders of consciousness. These breakthroughs question the historical nomenclature and our current management of post-comatose patients.MethodThis review examines the contribution of consciousness neurosciences to the current clinical management of severe brain injury. It investigates the major impact of consciousness disorders on healthcare systems, the scientific frameworks employed to identify their neural correlates and how evidence-based data from neuroimaging research have reshaped the landscape of post-coma care in recent years.ResultsOur increased ability to detect behavioral and neurophysiological signatures of consciousness has led to significant changes in taxonomy and clinical practice. We advocate for a multimodal framework for the management of severely brain-injured patients based on precision medicine and evidence-based decisions, integrating epidemiology, health economics and neuroethics.ConclusionsMajor progress in brain imaging and clinical assessment have opened the door to a new era of post-coma care based on standardized neuroscientific evidence. We highlight its implications in clinical applications and call for improved collaborations between researchers and clinicians to better translate findings to the bedside.     

The pars triangularis in dyslexia and ADHD: A comprehensive approach

Limited research has been conducted on the structure of the pars triangularis (PT) in dyslexia despite functional neuroimaging research finding it may play a role in phonological processing. Furthermore, research to date has not examined PT size in ADHD even though the right inferior frontal region has been implicated in the disorder. Hence, one of the purposes of this study was to examine the structure of the PT in dyslexia and ADHD. The other purposes included examining the PT in relation to overall expressive language ability and in relation to several specific linguistic functions given language functioning often is affected in both dyslexia and ADHD. Participants included 50 children: 10 with dyslexia, 15 with comorbid dyslexia/ADHD, 15 with ADHD, and 10 controls. Using a 2 (dyslexia or not) × 2 (ADHD or not) MANCOVA, findings revealed PT length and shape were comparable between those with and without dyslexia. However, children with ADHD had smaller right PT lengths than those without ADHD, and right anterior ascending ramus length was related to attention problems in the total sample. In terms of linguistic functioning, presence of an extra sulcus in the left PT was related to poor expressive language ability. In those with adequate expressive language functioning, left PT length was related to phonological awareness, phonological short-term memory and rapid automatic naming (RAN). Right PT length was related to RAN and semantic processing. Further work on PT morphology in relation to ADHD and linguistic functioning is warranted.     

Reappraisal inventiveness: impact of appropriate brain activation during efforts to generate alternative appraisals on the perception of chronic stress in women*

Background and objectives: Previous research indicated that more left-lateralized prefrontal activation during cognitive reappraisal efforts was linked to a greater capacity for generating reappraisals, which is a prerequisite for the effective implementation of cognitive reappraisal in everyday life. The present study examined whether the supposedly appropriate brain activation is relevant in terms of more distal outcomes, i.e., chronic stress perception.

Design and methods: Prefrontal EEG alpha asymmetry was recorded while female participants were generating reappraisals for stressful events and was correlated with their self-reported chronic stress levels in everyday life (n?=?80).

Results: Women showing less left-lateralized brain activity in the ventrolateral prefrontal cortex during cognitive reappraisal efforts reported experiencing more stress in their daily lives. This effect was independent of self-efficacy beliefs in managing negative emotions.

Conclusion: These findings underline the practical relevance of individual differences in appropriate brain activation during emotion regulation efforts and the assumedly related basic capacity for the generation of cognitive reappraisals to the feeling of being stressed. Implications include the selection of interventions for the improvement of coping with stress in women in whom the capability for appropriate brain activation during reappraisal efforts may be impaired, e.g., due to depression or old age.     

Does dyslexia develop from learning the alphabet in the wrong hemisphere? A cognitive neuroscience analysis

A new perspective is described which views developmental dyslexia as the outcome of learning to write the alphabet in the nondominant (right) hemisphere. The letter-level and whole-word subtypes of dyslexia are seen as differing responses adopted to cope with this predicament. Striking similarities between dyslexics and callosotomy patients in the allocation of covert attention to lateralized stimuli provide direction for integrating a diversity of dyslexic research within this framework. This synthesis, together with information from pure alexia, brain activation, and reading research, lends insight into the neural circuitry of the compensatory strategies adopted by the two dyslexic subtypes.     

深层失读及其认知神经心理康复

以语义性错读为特征的深层失读症是一类特殊的阅读障碍类型,它的存在提示了人类在口语阅读过程中需要经过语义性通路。深层失读在拼音文字使用者中并不多见,但在汉语使用者中却多有发现,这种差别提示了汉字阅读与拼音文字阅读之间可能存在某种重要区别。该文概要介绍了深层失读的表现,比较了汉语深层失读与拼音文字深层失读的差异,阐述了深层失读的机制,同时介绍了深层失读病人的神经心理康复手段和方法     

The supramodal brain: implications for auditory perception

ABSTRACT

The perceptual brain is designed around multisensory input. Areas once thought dedicated to a single sense are now known to work with multiple senses. It has been argued that the multisensory nature of the brain reflects a cortical architecture for which task, rather than sensory system, is the primary design principle. This supramodal thesis is supported by recent research on human echolocation and multisensory speech perception. In this review, we discuss the behavioural implications of a supramodal architecture, especially as they pertain to auditory perception. We suggest that the architecture implies a degree of perceptual parity between the senses and that cross-sensory integration occurs early and completely. We also argue that a supramodal architecture implies that perceptual experience can be shared across modalities and that this sharing should occur even without bimodal experience. We finish by briefly suggesting areas of future research.     

The brain basis of the phonological deficit in dyslexia is independent of IQ

Although the role of IQ in developmental dyslexia remains ambiguous, the dominant clinical and research approaches rely on a definition of dyslexia that requires reading skill to be significantly below the level expected given an individual's IQ. In the study reported here, we used functional MRI (fMRI) to examine whether differences in brain activation during phonological processing that are characteristic of dyslexia were similar or dissimilar in children with poor reading ability who had high IQ scores (discrepant readers) and in children with poor reading ability who had low IQ scores (nondiscrepant readers). In two independent samples including a total of 131 children, using univariate and multivariate pattern analyses, we found that discrepant and nondiscrepant poor readers exhibited similar patterns of reduced activation in brain areas such as left parietotemporal and occipitotemporal regions. These results converge with behavioral evidence indicating that, regardless of IQ, poor readers have similar kinds of reading difficulties in relation to phonological processing.