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1.
Albert M. Galaburda M.D. 《Annals of dyslexia》1989,39(1):65-80
Eight brains, six male and two female, of reliably diagnosed cases of developmental dyslexia have been analyzed in this laboratory
thus far. Common to all the specimens is the absence of ordinary asymmetry in the planum temporale, a language relevant area
of the temporal lobe. In addition, the male cases and one female case displayed multiple focal areas of malformation of the
cerebral cortex, located variably in the language relevant perisylvian regions and to a greater or lesser extent bilaterally.
Both female cases and, to a mild degree, one of the males display focal areas of cortical scarring dated to the end of pregnancy
through to the end of the second year of life at the latest. The scarring tends to be located in the vascular watershed territories.
Experimental animal research suggests that symmetry may represent absence of the necessary developmental pruning of neural
networks required for specific functions such as language. This diminished pruning results in excessive neurons and (at least
interhemispheric) connections.
Additional modeling in experimental animals suggests that cortical malformations and scarring similar to those seen in the
dyslexic brains may represent early focal injury that could be attributed to congenital disorders of the immune system.
The work reported here has been supported, in part, by NIH grant NICHD 20806, The Orton Dyslexia Society, and the Carl J.
Herzog Foundation. 相似文献
2.
Virginia W. Berninger 《Annals of dyslexia》2001,51(1):21-48
The historical roots of the IQ-achievement discrepancy definition of learning disability are discussed as a reference point
for explaining why this definition came into being and why it is inadequate for dealing with the variety of learning and developmental
disabilities that present in school settings. A proposal is offered and justified for defining learning disabilities on the
basis of profiles for multiple developmental domains that affect learning. In this proposal, developmental dyslexia is differentiated
from other learning disabilities. Developmental dyslexia is defined as uneven development (dissociation) between word reading
and higher-level processes in the functional reading system. Dyslexics may struggle with word reading because of deficits
in phonological processes, orthographic-phonological connections, and/or fluency (rate, automaticity, or executive coordination).
The need for both national and international classification schemes for defining specific learning and developmental disabilities
for the purposes of educational services and research is emphasized.
Grant P50 33812-06 from the National Institute of Child Health and Human Development supported preparation of this article. 相似文献
3.
阅读障碍是指词汇加工能力受损;而发展性阅读障碍是个体成长中出现的阅读障碍。一般从认知角度和生理基础角度出发研究阅读障碍的成因。通过对生理基础取向研究的回顾我们发现,发展性阅读障碍者阅读过程中的障碍存在脑部机能缺陷,主要包括脑电异常和脑功能异常。未来的研究应更加关注阅读障碍的定义,使之明确化;研究方法和手段要多元化;要开展多学科合作研究。 相似文献
4.
脑功能成像研究对语言功能一侧化的新认识 总被引：1，自引：0，他引：1
语言功能的半球一侧化是近一个半世纪以来科学研究的重要问题。近10多年来,运用fMRI、PET以及ERPs等脑功能成像手段,研究者发现语言功能的半球优势模式具有时间、空间的特异性和任务的相关性;它在个体发展的早期就已经显现,任务难度、生理成熟是影响一侧化年龄发展模式的重要中介因素;材料的语言属性而非物理特性可能是影响激活侧化的关键因素,语言功能的一侧化与大脑结构不对称性密切相关。这些结果大大丰富了人们对语言功能一侧化现象的认识,同时表明,运用脑功能成像技术,研究者已经开始触及到语言一侧化的核心问题,即其一侧化的内在认知与神经机制问题。 相似文献
5.
Drake D. Duane MD 《Annals of dyslexia》2002,52(1):25-42
Norman Geschwind had a profound effect on behavioral neurology, not only on the basis of his research and theories expressed
during his lifetime, but also through the impact that he had on colleagues privileged to train under him or have their work
personally influenced by him. My work falls into the latter category. Novel associations between brain function/structure
and behavior characterized his professional contributions, and offer a model for those who follow in his footsteps. He correctly
predicted that like aphasic disorders, developmental dyslexia might be associated with deficits in color naming expressed
currently as deficits in Rapid Automatized Naming. He stimulated anatomic research regarding patterns of asymmetry and microscopic
architecture leading to the establishment of the Orton Dyslexia Neuropathology Laboratory at Beth Israel Hospital, Boston.
He predicted an association between autoimmune disorders and reading disorders, an association that proved to be of genetic
origin. He further predicted that reading disorders, like language disorders, would be cross-cultural and, similarly, their
mechanism of production would be cross-cultural, although affected perhaps by the structure of the language to be learned.
His suspicion that the clinical impression of male gender preponderance in dyslexia was accurate and carried biologic significance
has recently been reconfirmed by colleagues at the Mayo Clinic in Rochester, Minnesota. Finally, with respect to dyslexia,
one should not be surprised that since affect is influenced by brain architecture, developmental disorders characterized by
altered brain architecture might be associated with affective or other psychiatric phenomena. My own work suggests that the
altered neuroanatomy in dyslexia may be accompanied by altered clinical neurophysiology, offering the possibility that in
some developmental disorders, behaviors, including academic aptitude and cognitive function, might benefit from medications
designed originally to lower the risk of clinical seizures. Perhaps Geschwind’s greatest lesson is to not assume that all
we have been taught as dogma is truth. Rather, we must have a willingness to make clear perceptions and draw conclusions that
come closer to the reality of the causal relationship between brain and behavior. 相似文献
6.
A controversy whether developmental dyslexia is qualitatively different from other forms of reading disability has existed
among reading specialists for many years because poor readers, regardless of the labels attached to them, resemble each other
symptomatically (i.e., in reading achievement). For this reason, it is difficult to establish a priori criteria based on symptoms
to identify dyslexia and compare it with other forms of reading disability. One possible solution to this impasse is to see
if poor readers differ in the etiology of their reading disability and, if they do, then to see whether one group of poor
readers fits the traditional definition of dyslexia. This strategy was adopted in the present study. In this paper, it was
hypothesized that the etiology of dyslexia is different from that of other forms of reading disability because there is a
difference in the components that malfunction in dyslexia and other forms of reading disability. Studies have shown that the
two components that account for a large proportion of variance in reading are decoding and comprehension. Previous studies
also indicate that dyslexic children are deficient in decoding skills but not necessarily in comprehension. In this study,
reading-disabled children were divided into two groups on the basis of their listening comprehension. Children whose listening
comprehension was at or above grade level were placed in one group; poor readers with below-grade-level listening comprehension
were placed in the second group. Both groups, however, were matched for reading comprehension. The two groups and a control
group of normal readers were administered a number of tasks that were designed to assess the efficiency of the components
of reading. It was found that poor readers with normal listening comprehension were deficient in tasks that involved grapheme-phoneme
conversion (Component I, decoding). When tested on tasks that minimized decoding requirements, their reading comprehension
was comparable to that of normal readers. In contrast, the group with sub-average listening comprehension was poor in measures
of reading comprehension, even when decoding requirements were minimal. With the exception of very few children, this group
also had adequate decoding skills. Because poor readers with normal listening comprehension had average or above average IQ,
they conform to the traditional definition of dyslexia. Poor readers with below average listening comprehension had below
average IQ and could be considered as “general reading backward.” It was, therefore, concluded that the etiology of developmental
dyslexia is different from that of general reading backwardness.
In this paper, the termetiology refers to proximal causal factors such as decoding and comprehension and not to distal causal factors such as genetic and
neurological characteristics. 相似文献
7.
8.
The present study evaluated the idea that the hemisphere-specific cognitive demands of reading and writing may induce task-specific maladaptive patterns of language lateralization in children with dyslexia. Situation-specific lateralization was examined in a repeated measures design under three dichotic listening conditions: baseline, concurrent reading, and concurrent writing. Twelve males with phonological dyslexia, 8 to 12 years old, were compared to 12 age-matched and 12 younger reading-matched good readers. Lateralization patterns were examined for condition-specific relationships to pseudoword decoding, word recognition, reading comprehension, spelling, and arithmetic. The results show that dyslexia is not related to incomplete lateralization or to a failure to inhibit verbal processing in the right hemisphere during reading and writing. Reading increased the lateralization of the children with dyslexia, which had a negative relation to arithmetic; writing caused a decrease in lateralization, which was linked specifically to deficits in phonological decoding and visual word recognition. The results suggest that children with dyslexia suffer from a selective linguistic vulnerability to left-hemisphere interference from the idiosyncratic attentional and processing demands of particular school tasks. Dyslexia is a much more dynamic and environmentally sensitive disorder than previously thought. 相似文献
9.
Hugh W. Catts 《Annals of dyslexia》1989,39(1):50-64
Despite recent developments in research and theory, investigators and practitioners continue to rely on rather traditional
definitions of dyslexia. This paper discusses some of the problems with traditional definitions and reviews a rapidly growing
body of research that suggests a more comprehensive definition. According to this definition, dyslexia is a developmental
language disorder that involves a deficit(s) in phonological processing. This disorder manifests itself in various phonological
difficulties as well as a specific reading disability. 相似文献
10.
This article addresses the problem of what constitutes effective remediation for developmental dyslexia, combining neuropsychological and applied cognitive perspectives on specific reading disability. Despite its high prevalence, whether the disorder is amenable to treatment and what constitutes effective treatment were questions which, until recently, remained essentially unaddressed by properly controlled evaluation studies. Positive results from controlled remediation studies and experimental training paradigms with disabled and poor reader samples are reviewed. As part of a clinical research program at The Hospital For Sick Children in Toronto, we have completed a series of treatment outcome studies with dyslexic samples (cumulative N = 285) in which we evaluated the efficacy of different programs designed to remediate the reading and reading-related deficits of dyslexic children and adolescents. Results from one of these studies are summarized to illustrate the unique perspective afforded through remedial outcome data: Emphasis is placed on what the results of such studies may reveal of dyslexic learning disabilities. 相似文献
11.
Until recently, many thought developmental dyslexia was a behavioral disorder that primarily affected reading. In fact, it
is a partly heritable condition, the clinical manifestations of which are extremely complex including deficits in reading,
working memory, sensorimotor coordination, and early sensory processing. Even though extensive research has characterized
these behavioral abnormalities carefully, the biological mechanisms of the clinical manifestations still are poorly understood.
Recent research into both the nature of the structural and functional abnormalities in developmental dyslexia and the functional
neuroanatomy of reading have rapidly advanced our understanding of the localization of the processes responsible for the signs
and symptoms of dyslexia. This paper reviews recent evidence supporting a biological basis for developmental dyslexia.
This article was made possible by grant NICHD HD36461 from The Charles A. Dana Foundation and The International Dyslexia Association. 相似文献
12.
The present study was designed to examine the question of whether developmental dyslexia in 12-year-old students at the beginning
of secondary education in the Netherlands is confined to problems in the domain of reading and spelling or also is related
to difficulties in other areas. In particular, hypotheses derived from theories on phonological processing, rapid automatized
naming, working memory, and automatization of skills were tested. To overcome the definition and selection problems of many
previous studies, we included in our study all students in the first year of secondary special education in a Dutch school
district. Participants were classified as either dyslexic, garden-variety, or hyperlexic poor readers, according to the degree
of discrepancy between their word recognition and listening comprehension scores. In addition, groups of normal readers were
formed, matching the poor readers in either reading age or chronological age. A large test battery was administered to each
student, including phonological, naming, working memory, speed of processing, and motor tests. The findings indicate that
dyslexia is associated with deficits in (1) phonological recoding, word recognition (both in their native Dutch and in English
as a second language), and spelling skills; and (2) naming speed for letters and digits. Dyslexia was not associated with
deficits in other areas. The results suggest that developmental dyslexia, at the age of 12, might be (or might have become)
a difficulty rather isolated from deficiencies in other cognitive and motor skills. 相似文献
13.
Itzhak Fried 《Annals of dyslexia》1979,29(1):101-112
Conclusions Evidence of different syndromes of developmental dyslexia raises the question of the interaction between dyslexic types and
patterns of cerebral dominance. Some of the proposed classifications of dyslexia, and most notably the one proposed by Boder
(1971), strongly suggest that dyslexic subtypes, that can be identified clinically by reading-spelling patterns, may possess
different or opposite cerebral dominance patterns. Thus, research of cerebral dominance in dyslexia (i.e., Orton’s hypothesis)
should involve careful selection and classification of subjects. When this is done it can be shown that electrophysiological
measures can identify cerebral-dominance abnormalities in at least one subtype of developmental dyslexia.
This paper was presented in part at the 29th Annual Conference of The Orton Society, November 1978, in Minneapolis, Minnesota. 相似文献
14.
The visual deficit hypothesis of development dyslexia has largely been abandoned because many of the phenomena that initially motivated it could not be replicated under controlled experimental conditions, while phonological processing deficits were found to provide a better explanation for the replicable phenomena. Nevertheless, many teachers and special educators continue to subscribe to the hypothesis that deficits of visual perception are a major cause of reading failure in dyslexia. As part of a larger family study, we reexamined the questions (1) whether probands and affected relatives in dyslexia families reverse easily confused letters more frequently under experimental conditions than normal readers from the same families, and (2) whether they show unusual facility in reading geometrically transformed text. The findings indicated that young dyslexia students reverse easily confused letters more often than normal readers. Reading group differences of letter reversal were significant in children from 7–10 years but not thereafter; and virtually no subject reversed letters when spelling whole words. Furthermore, dyslexic persons in every age group from 7–60 years actually took longer than normal readers to decode geometrically transformed text; and the time to decode transformed texts increased progressively with age after adolescence in both dyslexic persons and normal readers. Thus, reading group differences in decoding easily confused letters and reading geometrically transformed text do not support the visual deficit hypothesis and probably do not help to clarify the etiology of developmental dyslexia. 相似文献
15.
P. G. Aaron 《Annals of dyslexia》1993,43(1):110-124
Traditionally, it has been speculated that weaknesses in the visual processing of cognitive aspects of the written word could lead to reading problems, and if so, such a condition would constitute a subtype of developmental dyslexia. This putative subtype has been referred to as visual dyslexia. In this article, the role of cognitive deficits that are visual in nature as a potential etiological factor of developmental dyslexia is examined. Following a brief history of the study of dyslexia, a critique of studies of visual dyslexia is presented. Subsequently, the nature of the visual processes involved in word- recognition is examined. Finally, three research studies that assessed the contribution of visual memory to word-recognition are presented. It is concluded that, even though defects in the physiological aspects of visual processing can lead to reading difficulties, at present little convincing evidence is available to conclude that a subtype of dyslexia caused by cognitive deficits associated with visual processing of information exists. 相似文献
16.
Laura M. Steacy Ashley A. Edwards Jay G. Rueckl Yaacov Petscher Donald L. Compton 《Child development》2021,92(3):e252-e269
Developmental studies examining relations between word reading (WR) and decoding in typical and dyslexic populations routinely cut the reading distribution to form distinct groups. However, dichotomizing continuous variables to study development is problematic for multiple reasons. Instead, we modeled and visualized the parallel growth of WR and nonword reading (NWR) factor scores longitudinally in a Grade 1–4 developmental sample (N = 588). The results indicate that while WR and NWR growth factors are highly related (r = .71), the relation between WR and NWR trajectories change as a function of initial WR. Results are interpreted within computational models of dyslexia in which children with dyslexia overfit orthography → phonology relations at the level of the word, limiting the development of sublexical representations needed to read nonwords. 相似文献
17.
《Scientific Studies of Reading》2013,17(3):285-316
Linkage studies of complex phenotypes such as reading ability/disability (developmental dyslexia or reading disorder) and related componential processes, where the effects attributable to individual genes appear to be modest, are critically dependent on the nature and composition of the samples and the phenotypes analyzed. Thus, it might be helpful to consider the results from individual studies collectively so that summative profiles of findings can be considered. To gain an impression of how useful such an approach might be, a conservative meta-analysis based on Fisher's pooled p values approach was performed on regional linkage/association studies of developmental dyslexia and related phenotypes published through early September 2004. The obtained results rank order the findings and stress the need to contextualize the results with more regional linkage/association studies as well as with statistical simulation studies. 相似文献
18.
Gad Elbeheri John Everatt Gavin Reid Haya al Mannai 《Journal of Research in Special Educational Needs》2006,6(3):143-152
Despite advancements in empirical studies of developmental dyslexia, progress on methods of dyslexia assessment have been hampered by ongoing debate concerning diverse issues such as the role and validity of IQ in the assessment process, labelling and definitions ( Miles, 1994 ; Stanovich, 1991, 1992 ). With the emergence of cross-linguistic studies of dyslexia came the realisation that the manifestation of dyslexia is different in different languages ( Goulandris, 2003 ; Smythe, Everatt & Salter, 2004 ). It follows that the assessment of dyslexia should consider specific linguistic features of the language spoken by the individual to be assessed. This paper argues for the need of culture-fair assessment and calls for considerations to be given when assessing monolingual Arabic-speaking individuals with dyslexia which would take into account the specific linguistic feature of the Arabic language. 相似文献
19.
Albert M. Galaburda M.D. 《Annals of dyslexia》1985,35(1):19-33
The discovery of biological substrates underlying medical conditions is an important step for their better understanding and
for the design of appropriate medical therapies. In the case of developmental dyslexia pedagogic treatment may fail, thus
creating a group of individuals in whom medical approaches may be entertained. The biological substrate(s) of developmental
dyslexia has yet to be specified, although a few clues are beginning to emerge. In this review I consider the issue of cerebral
dominance and brain asymmetry, the development of the cerebral cortex and examples of aberrancy, and diseases of the immune
system, all of which relate to recent anatomical and epidemiological findings in developmental dyslexia. These discoveries
have been able to lead to the creation of testable hypotheses which, after appropriate experimental work, are apt to enhance
our current understanding of this and other developmental learning disorders. 相似文献