Dyslexia: the Role of Vision and Visual Attention

Brain Sciences

Reading acquisition is extremely difficult for about 5% of children because they are affected by a heritable neurobiological disorder called developmental dyslexia (DD). Intervention studies can be used to investigate the causal role of neurocognitive deficits in DD. Recently, it has been proposed that action video games (AVGs)—enhancing attentional control—could improve perception and working memory as well as reading skills. In a partial crossover intervention study, we investigated the effect of AVG and non-AVG training on attentional control using a conjunction visual search task in children with DD. We also measured the non-alphanumeric rapid automatized naming (RAN), phonological decoding and word reading before and after AVG and non-AVG training. After both video game training sessions no effect was found in non-alphanumeric RAN and in word reading performance. However, after only 12 h of AVG training the attentional control was improved (i.e., the set-size slopes were flatte...

Frontiers in Psychology, 2016

Reading is a highly complex process in which integrative neurocognitive functions are required. Visual-spatial abilities play a pivotal role because of the multi-faceted visual sensory processing involved in reading. Several studies show that children with developmental dyslexia (DD) fail to develop effective visual strategies and that some reading difficulties are linked to visual-spatial deficits. However, the relationship between visual-spatial skills and reading abilities is still a controversial issue. Crucially, the role that age plays has not been investigated in depth in this population, and it is still not clear if visual-spatial abilities differ across educational stages in DD. The aim of the present study was to investigate visual-spatial abilities in children with DD and in age-matched normal readers (NR) according to different educational stages: in children attending primary school and in children and adolescents attending secondary school. Moreover, in order to verify whether visual-spatial measures could predict reading performance, a regression analysis has been performed in younger and older children. The results showed that younger children with DD performed significantly worse than NR in a mental rotation task, a more-local visual-spatial task, a more-global visual-perceptual task and a visual-motor integration task. However, older children with DD showed deficits in the more-global visual-perceptual task, in a mental rotation task and in a visual attention task. In younger children, the regression analysis documented that reading abilities are predicted by the visual-motor integration task, while in older children only the moreglobal visual-perceptual task predicted reading performances. Present findings showed that visual-spatial deficits in children with DD were age-dependent and that visual-spatial abilities engaged in reading varied across different educational stages. In order to better understand their potential role in affecting reading, a comprehensive description and a multi-componential evaluation of visual-spatial abilities is needed with children with DD.

2021

Many children have undetected vision problems or insufficient visual information processing that may be a factor in lower academic outcomes. The aim of this paper is to contribute to a better understanding of the importance of vision screening for school-aged children, and to investigate the possibilities of how eye-tracking (ET) technologies can support this. While there are indications that these technologies can support vision screening, a broad understanding of how to apply them and by whom, and if it is possible to utilize them at schools, is lacking. We review interdisciplinary research on performing vision investigations, and discuss current challenges for technology support. The focus is on exploring the possibilities of ET technologies to better support screening and handling of vision disorders, especially by non-vision experts. The data orginate from a literature survey of peer-reviewed journals and conference articles complemented by secondary sources, following a rapid ...

2021

A universal signature of developmental dyslexia is literacy acquisition impairments. Besides, dyslexia may be related to deficits in selective spatial attention, in the sensitivity to global visual motion, speed processing, oculomotor coordination, and integration of auditory and visual information. Whether motion-sensitive brain areas of children with dyslexia can recognize different speeds of expanded optic flow and segregate the slow-speed from high-speed contrast of motion was a main question of the study. A combined event-related EEG experiment with optic flow visual stimulation and functional frequency-based graph approach (small-world propensity φ) were applied to research the responsiveness of areas, which are sensitive to motion, and also distinguish slow/fast -motion conditions on three groups of children: controls, untrained (pre-D) and trained dyslexics (post-D) with visual intervention programs. Lower φ at θ, α, γ1-frequencies (low-speed contrast) for controls than othe...

2021

EEG studies using graph-theoretic analysis have found aberrations in functional connectivity (FC) in dyslexics. How the visual training (VT) can change FC of the reading neural network (RNN) in developmental dyslexia is still unclear. We studied differences in local and global topological properties of FC-RNN between controls and dyslexic children before and after VT (pre-D, post-D). The minimum spanning tree method was used to construct RNN in multiple EEG frequency-bands. Pre-D had higher leaf fraction, tree hierarchy, kappa, and smaller diameter (h-c), therefore more loaded RNNs than at controls. The RNN-metrics of post-D became similar to controls. In b1 and c-frequency bands, pre-D exhibited reduced degree and betweenness centrality of hubs in superior, middle, inferior frontal areas in both hemispheres compared to controls. Dyslexics relied on left anterior temporal (b1,c1), dorsolateral prefrontal cortex (c1), while in right hemisphere-occipitotemporal, parietal (b1), motor (b2,c1), somatosensory cortices (c1). Post-D, hubs appeared in both hemispheric middle occipital (b), parietal (b1), somatosensory (c1), dorsolateral prefrontal cortices (c2), while in left hemisphere-at middle temporal, motor (b1), intermediate (c2), inferior frontal cortices (c1,b2). Language-related brain regions, more active after VT, contribute to lexical and sublexical understanding, as well areas, important for articulatory reading processes.

Current Developmental Disorders Reports, 2015

Impaired linguistic-phonological processing is the most accepted explanation of developmental dyslexia (DD). However, growing literature shows that DD is the result of the combination of several neurocognitive causes. Visual attention and magnocellular-dorsal (MD) pathway deficits are now considered causes of DD. Interestingly, a large portion of literature showed that action video games (AVG) are able to improve attentional and perceptual skills in typical readers. Consequently, employing AVG trainings in individuals with DD could improve attention and perception, resulting in better reading skills. The aim of our review is to show the benefits of the AVG training on DD through the changes in the neurocognitive functions at the basis of learning to read. Since visual attentional and MD dysfunctions can be diagnosed in infancy, our review paves the way for possible early prevention programs that could use AVG training.

Frontiers in Human Neuroscience, 2016

A visual illusion refers to a percept that is different in some aspect from the physical stimulus. Illusions are a powerful non-invasive tool for understanding the neurobiology of vision, telling us, indirectly, how the brain processes visual stimuli. There are some neurodevelopmental disorders characterized by visual deficits. Surprisingly, just a few studies investigated illusory perception in clinical populations. Our aim is to review the literature supporting a possible role for visual illusions in helping us understand the visual deficits in developmental dyslexia and autism spectrum disorder. Future studies could develop new tools-based on visual illusions-to identify an early risk for neurodevelopmental disorders.

Computational and mathematical methods in medicine, 2017

Dyslexia is a chronic problem that affects the life of subjects and often influences their life choices. The standard rehabilitation methods all use a classic paper and pencil training format but these exercises are boring and demanding for children who may have difficulty in completing the treatments. It is important to develop a new rehabilitation program that would help children in a funny and engaging way. A Wii-based game was developed to demonstrate that a short treatment with an action video game, rather than phonological or orthographic training, may improve the reading abilities in dyslexic children. According to the results, an approach using cues in the context of a virtual environment may represent a promising tool to improve attentional skills. On the other hand, our results do not demonstrate an immediate effect on reading performance, suggesting that a more prolonged protocol may be a future direction.

Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists), 2016

There are many anecdotal claims and research reports that coloured lenses and overlays improve reading performance. Here we present the results of a systematic review of this literature and examine the quality of the evidence. We systematically reviewed the literature concerning the effect of coloured lenses or overlays on reading performance by searching the PsychInfo, Medline and Embase databases. This revealed 51 published items (containing 54 data sets). Given that different systems are in use for issuing coloured overlays or lenses, we reviewed the evidence under four separate system headings (Intuitive, Irlen, Harris/Chromagen and Other), classifying each published item using the Cochrane Risk of Bias tool. Although the different colour systems have been subjected to different amounts of scientific scrutiny, the results do not differ according to the system type, or whether the sample under investigation was classified as having visual stress (or a similarly defined condition)...

Scientific Reports

Although learning disorders (LD) and developmental language disorder (DLD) can be linked to overlapping psychological and behavioral deficits, such as phonological, morphological, orthographic, semantic, and syntactic deficits, as well as academic (e.g., reading) difficulties, they are currently separate diagnoses in the DSM-5 with explicit phenotypic differences. At a neural level, it is yet to be determined to what extent they have overlapping or distinct signatures. The identification of such neural markers/endophenotypes could be important for the development of physiological diagnostic tools, as well as an understanding of disorders across different dimensions, as recommended by the Research Domain Criteria Initiative (RDoC). The current systematic review and meta-analysis examined whether the two disorders can be differentiated based on the auditory brainstem response (ABR). Even though both diagnoses require hearing problems to be ruled out, a number of articles have demonstr...

Indian Journal of Clinical and Experimental Ophthalmology

Patients with preeclampsia or eclampsia may be associated with hypertension, seizures and other neurologic symptoms and deficits. A young female patient presented with a neurological and visual disturbance which included variable symptoms like visual disturbances, headache, seizures and altered consciousness or mental status with a history of postpartum eclampsia after an uneventful LUCS. She also gave a history of a two-bag blood transfusion one month ago. A neurological and ophthalmic evaluation was performed. Detailed history taking and clinical evaluation followed by an imaging study, potentially magnetic resonance imaging (MRI), helped to confirm the diagnosis of Posterior reversible encephalopathy syndrome (PRES). PRES is a clinico-neuroradiological disorder of neurotoxicity that typically involves headache, mental confusion, seizures, and occasionally loss of vision. The exact pathophysiology of PRES is still unclear and has not been thoroughly explained. Hypertension and end...

Journal of Experimental Child Psychology, 2022

Relations of visual attention to reading have long been hypothesized; however, findings in this literature are quite mixed. These relations have been investigated using several different visual attention paradigms and with variable controls for other competing reading-related processes. We extended current knowledge by evaluating four of the key visual attention paradigms used in this research (visual attention span, attention blink, visual search, visuospatial attention) in a single study. We tested the relation of these to reading in 90 middle schoolers at high risk for reading difficulties, while considered their effect in the context of known language predictors. Performance on visual-spatial, visual search, and attentional blink paradigms showed weak, nonsignificant relations to reading. Visual attention span tasks showed robust relations with reading even when controlling for language, though only when stimuli were alphanumeric. Although further exploration of visual attention in relation to reading may be warranted, the robustness of this relationship appears questionable, particularly beyond methodological factors associated with the measurement of visual attention. Findings extend and refine our understanding of the contribution of attention to reading skill and raise questions about the mechanism by which visual attention is purported to affect reading.

Scientific reports, 2017

Previous research shows that dyslexic readers are impaired in their recognition of faces and other complex objects, and show hypoactivation in ventral visual stream regions that support word and object recognition. Responses of these brain regions are shaped by visual statistical learning. If such learning is compromised, people should be less sensitive to statistically likely feature combinations in words and other objects, and impaired visual word and object recognition should be expected. We therefore tested whether people with dyslexia showed diminished capability for visual statistical learning. Matched dyslexic and typical readers participated in tests of visual statistical learning of pairs of novel shapes that frequently appeared together. Dyslexic readers on average recognized fewer pairs than typical readers, indicating some problems with visual statistical learning. These group differences were not accounted for by differences in intelligence, ability to remember individu...

Cambridge University Press eBooks, 2019

Genes, Brain and Behavior, 2017

Although a genetic component is known to have an important role in the etiology of developmental dyslexia (DD), we are far from understanding the molecular etiopathogenetic pathways. Reduced measures of neurobiological functioning related to reading (dis)ability, i.e. endophenotypes (EPs), are promising targets for gene finding and the elucidation of the underlying mechanisms. In a sample of 100 nuclear families with DD (229 offspring) and 83 unrelated typical readers, we tested whether a set of well-established, cognitive phenotypes related to DD [i.e. rapid auditory processing (RAP), rapid automatized naming (RAN), multisensory nonspatial attention and visual motion processing] fulfilled the criteria of the EP construct. Visual motion and RAP satisfied all testable criteria (i.e. they are heritable, associate with the disorder, co-segregate with the disorder within a family and represent reproducible measures) and are therefore solid EPs of DD. Multisensory nonspatial attention satisfied three of four criteria (i.e. it associates with the disorder, co-segregates with the disorder within a family and represents a reproducible measure) and is therefore a potential EP for DD. Rapid automatized naming is heritable but does not meet other criteria of the EP construct. We provide the first evidence of a methodologically and statistically sound approach for identifying EPs for DD to be exploited as a solid alternative basis to clinical phenotypes in neuroscience.

Restorative Neurology and Neuroscience, 2018

Vision loss due to ocular diseases such as glaucoma, optic neuropathy, macular degeneration, or diabetic retinopathy, are generally considered an exclusive affair of the retina and/or optic nerve. However, the brain, through multiple indirect influences, has also a major impact on functional visual impairment. Such indirect influences include intracerebral pressure, eye movements, top-down modulation (attention, cognition), and emotionally triggered stress hormone release affecting blood vessel dysregulation. Therefore, vision loss should be viewed as the result of multiple interactions within a "brain-eye-vascular triad", and several eye diseases may also be considered as brain diseases in disguise. While the brain is part of the problem, it can also be part of the solution. Neuronal networks of the brain can "amplify" residual vision through neuroplasticity changes of local and global functional connectivity by activating, modulating and strengthening residual visual signals. The activation of residual vision can be achieved by different means such as vision restoration training, non-invasive brain stimulation, or blood flow enhancing medications. Modulating brain functional networks and improving vascular regulation may offer new opportunities to recover or restore low vision by increasing visual field size, visual acuity and overall functional vision. Hence, neuroscience offers new insights to better understand vision loss, and modulating brain and vascular function is a promising source for new opportunities to activate residual vision to achieve restoration and recovery to improve quality of live in patients suffering from low vision.