Different Impairments Contribute to Neglect Dyslexia

Abstract

We report investigations of the reading abilities of SP, a right-handed woman who had suffered a sub-arachnoid haemorrhage from a right middle cerebral artery aneurysm. When reading text SP showed “neglect dyslexia”. She omitted words from the left side of the page and often misread the beginnings of words, either by deleting (e.g. WANT read as “ant”) or substituting (BAND read as “sand”) their initial letters. SP's tendency to omit words was markedly affected by their position along the left-right axis, yet the same variable did not affect her tendency to make initial-letter misreadings in the same way. When words were presented so that their beginnings fell in the hemianopic region of her visual field she showed a marked tendency to make misreadings involving the deletion of initial letters. In contrast, when words were presented so that they had fallen entirely in the intact part of her field of vision, SP made errors that were mostly initial-letter substitutions. We thus suggest that neglect dyslexia involves different underlying impairments, which are often (but not inevitably) present in combination with each other. Words are omitted from the left side of the page because of defective location of line beginnings. Initial-letter deletions occur primarily when the patient fails to make adequate compensatory eye movements to words that have been fixated with their beginnings falling in the hemianopic area of the visual field. Initial-letter substitutions, however, reflect damage to mechanisms involved in letter and word recognition.     

Right Neglect Dyslexia: A Single Case Study

Abstract

A single case study of a right neglect dyslexic is reported. The patient's (RYT) single word reading difficulty was characterised by paralexic errors that affected word endings. An analysis of the error corpus demonstrates the maintenance of word length in his error responses and a gradient of accuracy across individual words irrespective of their length. The actual neglect point was found to be a function of word length. It is concluded that right neglect dyslexia is a reading-specific deficit in which there is activation of an inappropriate visual word form.     

Two-Character Chinese Compound Word Processing in Chinese Children With and Without Dyslexia: ERP Evidence

Using event-related potential (ERP) measures, we examined the time course of Chinese compound word processing in 15 dyslexic and 10 normal children in a lexical decision task with three conditions including real words (e.g., (house)), reversed nonwords (e.g., can be transposed to a real word (ocean)) and random nonwords (e.g., is not a real word when transposing). Behavioral results showed that dyslexic children performed slower and less accurately than normal children did across conditions. ERP data revealed that normal children exhibited significant N400 effects across conditions. The dyslexics did not show any difference on N400, however, suggesting a possible weakness of morphological processing in dyslexic children.     

Developmental Dyslexia With and Without Language Impairment: ERPs Reveal Qualitative Differences in Morphosyntactic Processing

This study aimed to characterize neuropsychological and linguistic skills in children with Developmental Dyslexia (DD) with and without Language Impairment (LI). Behavioral tests of short-term memory, phonemic awareness, and morphosyntactic processing and electrophysiological responses to agreement violations were administered to 32 DD children (16 with additional LI) and 16 controls. Behavioral data revealed quantitative differences among groups: DD+LI children showed the worst performance, followed by DD-only children and controls. Event-related potential results confirmed atypical morphosyntactic processing in the DD-only group, highlighting qualitative differences between groups. These results support multifactor models of learning disabilities, where different patterns of deficits characterize different subgroups.     

Rehearsal Strategies and Recall Performance in Boys With and Without Attention Deficit Hyperactivity Disorder

Examined differences in recall performance and rehearsal strategiesin boys with Attention Deficit Hyperactivity Disorder (ADHD)and comparison boys using an overt rehearsal procedure on aself-paced, multitrial, free recall task. Boys with ADHD recalledfewer words, tended to spend less time rehearsing the items,and spent less time attempting to retrieve them. Although theydid not rehearse items less frequently than comparison boys,they relied almost exclusively on repetition of single items.In contrast, comparison boys showed some evidence of using active,multi-item (cumulative) rehearsal. Despite their failure touse cumulative rehearsal, boys with ADHD identified it as moreeffective than single-item rehearsal in a subsequent forced-choiceassessment of strategy knowledge.     

忽视症多感觉通道缺陷研究的新进展

忽视症可表现为多感觉通道缺陷。该文着重综述了与视觉忽视并存的听觉忽视。视觉忽视的病人常表现出对病损对侧声音的定位缺陷，尤其是当病损同侧存在竞争性声音刺激时，视觉和听觉缺陷的严蘑程度有硅著的相关性。神经影像学研究结果表明，忽视症病人受损的脑区可能与多感觉通道的空间表征有关。     

Response Inhibition and Attention Deficit Hyperactivity Disorder With and Without Oppositional Defiant Disorder Screened From a Community Sample

The study compared performance of children with high levels of attention deficit hyperactivity disorder (ADHD; n = 22), children with ADHD and oppositional defiant disorder (ODD; n = 19), and a control group (n = 20) on a Go-No-go test in a self-paced and computer-paced condition. Each condition, in turn, was run in a reward and a nonreward condition. The children were recruited through screening of a school population without ADHD or ODD (N = 450). Findings indicated that children having high levels of ADHD plus ODD showed poor impulse control in all 4 conditions. No poor impulse control was found in the group with high levels of ADHD. This group demonstrated slower RTs across the computer-paced conditions. Findings were discussed in terms of the response-inhibition hypothesis, as formulated by Barkley (1997), the delay-aversion theory (Sonuga-Barke, 1995), and the state-regulation theory (Van der Meere, 2002).     

Developmental Pathways of Children With and Without Familial Risk for Dyslexia During the First Years of Life

Comparisons of the developmental pathways of the first 5 years of life for children with (N = 107) and without (N = 93) familial risk for dyslexia observed in the Jyvaskyla Longitudinal study of Dyslexia are reviewed. The earliest differences between groups were found at the ages of a few days and at 6 months in brain event-related potential responses to speech sounds and in head-turn responses (at 6 months), conditioned to reflect categorical perception of speech stimuli. The development of vocalization and motor behavior, based on parental report of the time of reaching significant milestones, or the growth of vocabulary (using the MacArthur Communicative Development Inventories) failed to reveal differences before age 2. Similarly, no group differences were found in cognitive and language development assessed by the Bayley Scales of Infant Development and the Reynell Developmental Language Scales before age 2.5. The earliest language measure that showed lower scores among the at-risk group was maximum sentence length at age 2. Early gross motor development had higher correlation to later language skills among the at-risk group rather than the control children. The most consistent predictor of differential development between groups was the onset of talking. Children who were identified as late talkers at age 2 were still delayed at the age 3.5 in most features of language-related skills-but only if they belonged to the group at familial risk for dyslexia. Several phonological and naming measures known to correlate with reading from preschool age differentiated the groups consistently from age 3.5. Our findings imply that a marked proportion of children at familial risk for dyslexia follow atypical neurodevelopmental paths. The signs listed previously comprise a pool of candidates for early predictors and precursors of dyslexia, which await validation.     

Auditory and Visual Processing in Children With Dyslexia

This study investigated the temporal stability and longitudinal replicability of visual and auditory sensory processes found to be poor in children with dyslexia. Seventy children with dyslexia and 52 normal readers were tested twice, 9 months apart, on measures of visual and auditory sensory processing and on phonological and orthographic skills. About 30% of children with dyslexia were found to have sensory deficits. Associations were found between sensory and cognitive skills. Based on analyses of agreement, the temporal stability of the sensory tasks was poor. Future research should develop sensory measures with high temporal stability that can control for maturation.     

Directing Attention to Words and Nonwords in Normal Subjects and in a Computational Model: Implications for Neglect Dyslexia

Abstract

In a previous paper, we proposed that patients with neglect dyslexia process information appearing on the unattended side. This information, if encoded sufficiently, may be used to trigger top-down knowledge, leading to the interaction of spatial attention and lexicality. The current studies examine this question in normal people. Subjects' attention was biased to the end of a letter string by a cue (underline bar) and lexical decisions were made to the underlined section of the letter string (for example, east and garm). These studies showed that reaction times were slower when distracting information appeared on the left than when no distractors were present (for example, arm). Furthermore, when the distractors played a lexical role and formed a word with the underlined string (for example, farm), lexical decisions were even slower. These results showed that distractors are processed at least to the level of lexical access and influence reading performance of the attended underlined string. We have also considered these findings in the light of an existing connectionist network of spatial attention and word recognition and have accounted for the data in a series of simulations. The convergence of findings from the neuropsychological, cognitive, and computational work supports the interaction between attention and higher-order lexical knowledge.     

Severity of Adolescent Delinquency Among Boys With and Without Attention Deficit Hyperactivity Disorder: Predictions From Early Antisocial Behavior and Peer Status

This study evaluated predictors of adolescent delinquency severity (11 to 17 years of age) among a diverse group of preadolescent boys with attention deficit hyperactivity disorder (ADHD; n = 100) and age-matched comparison boys (n = 75). During childhood, baseline assessments yielded diagnostic information, and naturalistic summer programs provided multimethod measures of overt aggression, covert antisocial behavior (ASB), and peer status. Five years later, multi-informant measures of ASB and delinquency were gathered and independently rated. Baseline ADHD, overt aggression, and peer status were not significantly related to adolescent delinquency severity. Observed noncompliance and an objective measure of covert ASB each independently predicted delinquency. Covert ASB predicted delinquency severity more strongly for comparison boys than for probands.     

Reaction Time Variability in Children With ADHD Symptoms and/or Dyslexia

Reaction time (RT) variability on a Stop Signal task was examined among children with attention deficit hyperactivity disorder (ADHD) symptoms and/or dyslexia in comparison to typically developing (TD) controls. Children's go-trial RTs were analyzed using a novel ex-Gaussian method. Children with ADHD symptoms had increased variability in the fast but not the slow portions of their RT distributions compared to those without ADHD symptoms. The RT distributions of children with dyslexia were similar to those of TD-controls. It is argued that variability in responding may be underpinned by impairments in response preparation or timing during Stop Signal tasks.     

Parenting Stress and the Child With Attention Deficit Hyperactivity Disorder

Presents a critical review of research concerning the stress of parenting a child with attention deficit hyperactivity disorder (ADHD). Four lines of research have been pursued. First, studies demonstrate increased stress reported by parents of hyperactive children. Second, studies of parental psychopathology suggest that for some parents such disturbance is independent of the child's pathology and reflects a genetic substrate for the same and related disorders. Third, ADHD is associated with increased parental marital discord. Fourth, research regarding parent-child interaction patterns suggests a child-to-adult direction of effect more than the reverse. Directions for future research are recommended.     

Converging Evidence for Triple Word Form Theory in Children With Dyslexia

This article has 3 parts. The 1st part provides an overview of the family genetics, brain imaging, and treatment research in the University of Washington Multidisciplinary Learning Disabilities Center (UWLDC) over the past decade that points to a probable genetic basis for the unusual difficulty that individuals with dyslexia encounter in learning to read and spell. Phenotyping studies have found evidence that phonological, orthographic, and morphological word forms and their parts may contribute uniquely to this difficulty. At the same time, reviews of treatment studies in the UWLDC (which focused on children in Grades 4 to 6) and other research centers provide evidence for the plasticity of the brain in individuals with dyslexia. The 2nd part reports 4 sets of results that extend previously published findings based on group analyses to those based on analyses of individual brains and that support triple word form awareness and mapping theory: (a) distinct brain signatures for the phonological, morphological, and orthographic word forms; (b) crossover effects between phonological and morphological treatments and functional magentic resonance imaging (fMRI) tasks in response to instruction, suggestive of cross-word form computational and mapping processes; (c) crossover effects between behavioral measures of phonology or morphology and changes in fMRI activation following treatment; and (d) change in the relationship between structural MRI and functional magnetic resonance spectroscopy (fMRS) lactate activation in right and left inferior frontal gyri following treatment emphasizing the phonological, morphological, and orthographic word forms. In the 3rd part we discuss the next steps in this programmatic research to move beyond word form alone.     

Functional Alterations in Order Short-Term Memory Networks in Adults With Dyslexia

Dyslexia is characterized not only by reading impairment but also by short-term memory (STM) deficits, and this particularly for the retention of serial order information. Here, we explored the functional neural correlates associated with serial order STM performance of adults with dyslexia for verbal and visual STM tasks. Relative to a group of age-matched controls, the dyslexic group showed abnormal activation in a network associated with order STM encompassing the right intraparietal and superior frontal sulcus, and this for both verbal and visual order STM conditions. This study highlights long-lasting alterations in non-language neural substrates and processes in dyslexia.     

Contribution of Executive Functions to Visuospatial Difficulties in Prepubertal Girls With Turner Syndrome

Turner syndrome (TS) is a genetic disorder caused by the absence of one X-chromosome in females. Individuals with TS often demonstrate a cognitive profile characterized by poor visuospatial abilities, which may in part be due to executive function impairments. Here, we assessed the neuropsychological profile of 36 prepubertal girls with TS and 20 typically developing children to examine the relationship between executive function and visuospatial abilities. Multiple linear regression analyses revealed that executive functions were closely associated with visuospatial abilities in TS but not in controls. These results suggest that executive dysfunctions observed in TS contribute to their visuospatial impairments.