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Lorusso ML, Toraldo A. Revisiting Multifactor Models of Dyslexia: Do They Fit Empirical Data and What Are Their Implications for Intervention? Brain Sci 2023; 13:brainsci13020328. [PMID: 36831871 PMCID: PMC9954758 DOI: 10.3390/brainsci13020328] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/09/2023] [Accepted: 02/11/2023] [Indexed: 02/17/2023] Open
Abstract
Developmental dyslexia can be viewed as the result of the effects of single deficits or multiple deficits. This study presents a test of the applicability of a multifactor-interactive model (MFi-M) with a preliminary set of five variables corresponding to different neuropsychological functions involved in the reading process. The model has been tested on a sample of 55 school-age children with developmental dyslexia. The results show that the data fit a model in which each variable contributes to the reading ability in a non-additive but rather interactive way. These findings constitute a preliminary validation of the plausibility of the MFi-M, and encourage further research to add relevant factors and specify their relative weights. It is further discussed how subtype-based intervention approaches can be a suitable and advantageous framework for clinical intervention in a MFi-M perspective.
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Affiliation(s)
- Maria Luisa Lorusso
- Scientific Institute IRCCS E. Medea, 23842 Bosisio Parini, Italy
- Correspondence:
| | - Alessio Toraldo
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
- Milan Center for Neuroscience, NeuroMI, 20126 Milan, Italy
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2
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Neuropsychological and Neurophysiological Mechanisms behind Flickering Light Stimulus Processing. BIOLOGY 2022; 11:biology11121720. [PMID: 36552230 PMCID: PMC9774938 DOI: 10.3390/biology11121720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 11/29/2022]
Abstract
The aim of this review is to summarise current knowledge about flickering light and the underlying processes that occur during its processing in the brain. Despite the growing interest in the topic of flickering light, its clinical applications are still not well understood. Studies using EEG indicate an appearing synchronisation of brain wave frequencies with the frequency of flickering light, and hopefully, it could be used in memory therapy, among other applications. Some researchers have focused on using the flicker test as an indicator of arousal, which may be useful in clinical studies if the background for such a relationship is described. Since flicker testing has a risk of inducing epileptic seizures, however, every effort must be made to avoid high-risk combinations, which include, for example, red-blue light flashing at 15 Hz. Future research should focus on the usage of neuroimaging methods to describe the specific neuropsychological and neurophysiological processes occurring in the brain during the processing of flickering light so that its clinical utility can be preliminarily determined and randomised clinical trials can be initiated to test existing reports.
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3
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Vernet M, Jover M, Bellocchi S, Maziero S, Jucla M, Tallet J, Danna J, Chaix Y, Ducrot S. Visual-processing deficits in children with neurofibromatosis type 1: A clinical marker of reading difficulties. Eur J Paediatr Neurol 2022; 38:25-32. [PMID: 35381410 DOI: 10.1016/j.ejpn.2022.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 03/07/2022] [Accepted: 03/23/2022] [Indexed: 11/24/2022]
Abstract
Today's estimates indicate that nearly 50% of children with Neurofibromatosis type 1 (NF1) suffer from reading disabilities, with a high impact on their academic achievement. In addition to the well-documented importance of phonological skills in reading acquisition and neurodevelopmental disorders, visual-attention processes also appear as important factors in learning to read. The present study aimed at assessing the role of visual-processing dysfunction in the high prevalence of reading disabilities in NF1 children and providing a useful tool for clinician in the early detection of reading impairment in this neurogenetic disorder. Forty-two children with NF1 and 42 typically developing children (TD) participated in the study. All were right-handed and did not present intellectual disability or attention deficit hyperactivity disorder. Visual-attention processes were assessed with the Developmental Eye Movement (DEM) test, together with the NF1 children's reading level. NF1 children with and without reading disabilities were then compared. The results showed that visual-processing deficits were highly present among the NF1 children included in our study. Furthermore, poor readers with NF1 presented an increased risk of visual-processing deficits compared to peers. This finding supports the role of visual-processing deficits in the reading difficulties encountered in nearly half of children with NF1. Finally, in NF1 children without intellectual or attention disability, visual-processing deficits emerge as one of the clinical markers of reading disabilities. The study holds important clinical implications both for the identification, by providing a useful screening tool, and the management of reading disabilities in NF1 children.
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Affiliation(s)
- Marie Vernet
- ToNIC, Toulouse NeuroImaging Center, University of Toulouse, Inserm, UPS, France; Aix Marseille Univ, CNRS, LPL, Aix-en-Provence, France.
| | | | - Stéphanie Bellocchi
- Univ. Paul Valéry Montpellier 3, Univ. Montpellier, EPSYLON EA, 4556, Montpellier, France
| | - Stéphanie Maziero
- ToNIC, Toulouse NeuroImaging Center, University of Toulouse, Inserm, UPS, France; Octogone-Lordat, University of Toulouse, Toulouse, France
| | - Mélanie Jucla
- Octogone-Lordat, University of Toulouse, Toulouse, France
| | - Jessica Tallet
- ToNIC, Toulouse NeuroImaging Center, University of Toulouse, Inserm, UPS, France
| | - Jérémy Danna
- Aix Marseille Univ, CNRS, LNC, Marseille, France
| | - Yves Chaix
- ToNIC, Toulouse NeuroImaging Center, University of Toulouse, Inserm, UPS, France; Children's Hospital, Toulouse-Purpan University Hospital, Toulouse, France
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4
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Freire MR, Pammer K. Reading as A Cultural Tool for Neurocognitive Development: A Complex Interactive Relationship between Reading Acquisition and Visuospatial Development for Indigenous and non-Indigenous Australians. JOURNAL OF COGNITION AND DEVELOPMENT 2022. [DOI: 10.1080/15248372.2022.2037606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Melissa R. Freire
- Research School of Psychology, Australian National University, Australia
| | - Kristen Pammer
- Research School of Psychology, Australian National University, Australia
- School of Psychology, University of Newcastle, Australia
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5
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The impairment of the visual-spatial attention in Chinese children with dyslexia: A cognitive deficit or a developmental delay? CURRENT PSYCHOLOGY 2021. [DOI: 10.1007/s12144-021-01753-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Abstract
BACKGROUND Under some conditions, the time required for a visual search increases with the number of elements to be searched. It has been suggested that the overall search time reflects the duration that attention is devoted to each element multiplied by the number of elements. On this basis, it has been proposed that visual search time can be used as a measure of attention capability in dyslexic readers. However, there is evidence to suggest that the search time reflects task difficulty rather than attentional factors. Many dyslexic readers suffer from various sensory deficits. These deficits would effectively increase task difficulty for these readers. Here we use computer simulations to investigate the potential effects of sensory deficits on visual search. METHOD Visual search was modelled on a computer within the framework of signal detection theory as a matter of detecting a noisy signal from a series of noisy distractors. Sensory deficits were modelled as decreased discriminability. RESULTS Consistent with previous observations, we find that discriminability, which decreases with the number of distractors, may have a substantial effect on the search time. With regard to the effects of sensory deficits, we find that under low discriminability conditions, small sensory deficits may cause pronounced increases in search time. CONCLUSION The finding that small sensory deficits may cause pronounced increases in search time makes it specifically problematic to use visual search to test attention in individuals who suffer from sensory deficits. This applies particularly to dyslexic individuals, many of whom have been shown to suffer from visual deficiencies.
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7
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Peters JL, Bavin EL, Crewther SG. Eye Movements During RAN as an Operationalization of the RAN-Reading "Microcosm". Front Hum Neurosci 2020; 14:67. [PMID: 32194388 PMCID: PMC7063464 DOI: 10.3389/fnhum.2020.00067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 02/12/2020] [Indexed: 11/13/2022] Open
Abstract
Rapid Automatized Naming (RAN) is a strong predictor of reading aloud, though there is little agreement on what underpins RAN or how it relates to reading. Some theorize phonological skills, while others suggest that RAN reflects the “microcosm” of cognitive and attentional processes also required for reading, with more recent research using eye movements in an attempt to study this relationship. In the current study, we aimed to extend previous investigations to identify whether the temporal patterns of eye movements predict RAN and can, therefore, be established as a method to study the cognitive processes underlying RAN that could then be utilized to elucidate the relationship of RAN to reading. A Gazepoint eye tracker was used to record the eye movements of 93 learner readers aged 5–8 years (M age = 7.00) while performing a custom computerized alphabetic RAN task. Text reading accuracy, comprehension and rate; nonverbal intelligence; and phonological awareness abilities were also assessed. Regression analyses showed that, independently of phonological awareness, eye movements [Fixation Count (FC) and Fixation Duration (FD)] measured during RAN tasks were highly reflective of children’s rapid naming performance (92.8%). Both mean FC and mean FD during RAN tasks also predicted text reading accuracy (36.3%), comprehension (31.6%), and rate (36.2%) scores, and in predicting these text reading skills there was a high level of shared variance with RAN performance. In a sub-sample of participants, longer average FDs and counts independently discriminated children with reading difficulties (n = 18; aged 7–9) from neurotypical children matched for age (n = 18), but not from younger neurotypical children matched for reading level (n = 18; aged 5–6). Together, these results suggest that the analysis of eye movements recorded during RAN allows for the operationalization of many of the spatially and temporally-bound cognitive and attentional processes that underpin the RAN, and a step towards elucidating its relationship to reading.
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Affiliation(s)
- Jessica Lee Peters
- Department of Psychology and Counselling, La Trobe University, Melbourne, VIC, Australia
| | - Edith Laura Bavin
- Department of Psychology and Counselling, La Trobe University, Melbourne, VIC, Australia.,Intergenerational Health, Murdoch Childrens Research Institute, Melbourne, VIC, Australia
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8
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Razuk M, Lukasova K, Bucci MP, Barela JA. Dyslexic children need more robust information to resolve conflicting sensory situations. DYSLEXIA (CHICHESTER, ENGLAND) 2020; 26:52-66. [PMID: 31680390 DOI: 10.1002/dys.1641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 07/09/2019] [Accepted: 10/21/2019] [Indexed: 06/10/2023]
Abstract
The study involved investigating dyslexic children's postural control responses when visual and somatosensory cues were separately manipulated. Twenty dyslexic and 19 nondyslexic children performed a trial by standing upright inside a moving room and another by lightly touching a moving bar. Both trials lasted 240 s with the following three different stimulus characteristics: low (pretransition), high (transition), and low amplitude (posttransition). Body sway magnitude and the relationship between the movement of the room/bar surface and body sway were examined. When compared to nondyslexic children, dyslexic children oscillated with higher magnitude in the transition and posttransition under visual and somatosensory manipulation; their sway was more influenced by visual manipulation in the transition and posttransition, and they used higher applied force levels in the somatosensory modality in all conditions. The results suggest that dyslexic children could not efficiently reweight visual cues when compared to nondyslexic children. The same was not observed in the somatosensory cues when dyslexic children reduced the influence of the somatosensory stimulus. The proper use of somatosensory information was related to stronger acquired cues and higher applied forces as observed for dyslexic children. Dyslexic children experience difficulties in dynamically reweighting sensory cues although these types of difficulties are overcome when more informative sensory cues are provided.
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Affiliation(s)
- Milena Razuk
- Institute of Physical Activity and Sport Sciences, Cruzeiro do Sul University, São Paulo, Brazil
| | - Katerina Lukasova
- Center of Mathematics, Computing and Cognition, Federal University of ABC, São Paulo, Brazil
| | - Maria Pia Bucci
- UMR 1141 Inserm, Hôpital Robert Debré, Université Paris Diderot, Paris, France
| | - José Angelo Barela
- Institute of Physical Activity and Sport Sciences, Cruzeiro do Sul University, São Paulo, Brazil
- Institute of Biosciences, São Paulo State University, Rio Claro, Brazil
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9
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Efficacy of dynamic visuo-attentional interventions for reading in dyslexic and neurotypical children: A systematic review. Neurosci Biobehav Rev 2019; 100:58-76. [DOI: 10.1016/j.neubiorev.2019.02.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/10/2018] [Accepted: 02/19/2019] [Indexed: 11/21/2022]
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10
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Veispak A, Ghesquière P. Could Specific Braille Reading Difficulties Result from Developmental Dyslexia? JOURNAL OF VISUAL IMPAIRMENT & BLINDNESS 2019. [DOI: 10.1177/0145482x1010400406] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A proportion of children with visual impairments have specific reading difficulties that cannot be easily explained. This article reviews the data on problems with braille reading and interprets them from the framework of the temporal–processing deficit theory of developmental dyslexia.
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Affiliation(s)
- Anneli Veispak
- Center for Parenting, Child Welfare and Disabilities, Katholieke Universiteit Leuven, Vesaliusstraat 2—bus 3765, 3000 Leuven, Belgium
| | - Pol Ghesquière
- Center for Parenting, Child Welfare and Disabilities, Katholieke Universiteit Leuven, Vesaliusstraat 2—bus 3765, 3000 Leuven, Belgium
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11
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Severino L, Tecce DeCarlo MJ, Sondergeld T, Izzetoglu M, Ammar A. A Validation Study of a Middle Grades Reading Comprehension Assessment. ACTA ACUST UNITED AC 2018. [DOI: 10.1080/19404476.2018.1528200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Lori Severino
- School of Education, Drexel University, Philadelphia, PA, USA
| | | | - Toni Sondergeld
- School of Education, Drexel University, Philadelphia, PA, USA
| | | | - Alia Ammar
- Drexel University, Philadelphia, PA, USA
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12
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Kermani M, Verghese A, Vidyasagar TR. Attentional asymmetry between visual hemifields is related to habitual direction of reading and its implications for debate on cause and effects of dyslexia. DYSLEXIA (CHICHESTER, ENGLAND) 2018; 24:33-43. [PMID: 29214682 DOI: 10.1002/dys.1574] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 10/11/2017] [Accepted: 11/01/2017] [Indexed: 06/07/2023]
Abstract
A major controversy regarding dyslexia is whether any of the many visual and phonological deficits found to be correlated with reading difficulty cause the impairment or result from the reduced amount of reading done by dyslexics. We studied this question by comparing a visual capacity in the left and right visual hemifields in people habitually reading scripts written right-to-left or left-to-right. Selective visual attention is necessary for efficient visual search and also for the sequential recognition of letters in words. Because such attentional allocation during reading depends on the direction in which one is reading, asymmetries in search efficiency may reflect biases arising from the habitual direction of reading. We studied this by examining search performance in three cohorts: (a) left-to-right readers who read English fluently; (b) right-to-left readers fluent in reading Farsi but not any left-to-right script; and (c) bilingual readers fluent in English and in Farsi, Arabic, or Hebrew. Left-to-right readers showed better search performance in the right hemifield and right-to-left readers in the left hemifield, but bilingual readers showed no such asymmetries. Thus, reading experience biases search performance in the direction of reading, which has implications for the cause and effect relationships between reading and cognitive functions.
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Affiliation(s)
- Mojtaba Kermani
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Vic, Australia
| | - Ashika Verghese
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Vic, Australia
- School of Psychology, University of Queensland, St. Lucia, QLD, Australia
| | - Trichur R Vidyasagar
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Vic, Australia
- Melbourne Neuroscience Institute, University of Melbourne, Parkville, Vic, Australia
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13
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Conlon EG, Power GF, Hine TJ, Rahaley N. The Impact of Older Age and Sex on Motion Discrimination. Exp Aging Res 2017; 43:55-79. [DOI: 10.1080/0361073x.2017.1258226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Elizabeth G. Conlon
- School of Applied Psychology and Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Garry F. Power
- School of Applied Psychology and Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Trevor J. Hine
- School of Applied Psychology and Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Nicole Rahaley
- School of Applied Psychology and Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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14
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Zhou T, Náñez JE, Zimmerman D, Holloway SR, Seitz A. Two Visual Training Paradigms Associated with Enhanced Critical Flicker Fusion Threshold. Front Psychol 2016; 7:1597. [PMID: 27833569 PMCID: PMC5080338 DOI: 10.3389/fpsyg.2016.01597] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 10/03/2016] [Indexed: 11/13/2022] Open
Abstract
Critical flicker fusion thresholds (CFFTs) describe when quick amplitude modulations of a light source become undetectable as the frequency of the modulation increases and are thought to underlie a number of visual processing skills, including reading. Here, we compare the impact of two vision-training approaches, one involving contrast sensitivity training and the other directional dot-motion training, compared to an active control group trained on Sudoku. The three training paradigms were compared on their effectiveness for altering CFFT. Directional dot-motion and contrast sensitivity training resulted in significant improvement in CFFT, while the Sudoku group did not yield significant improvement. This finding indicates that dot-motion and contrast sensitivity training similarly transfer to effect changes in CFFT. The results, combined with prior research linking CFFT to high-order cognitive processes such as reading ability, and studies showing positive impact of both dot-motion and contrast sensitivity training in reading, provide a possible mechanistic link of how these different training approaches impact reading abilities.
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Affiliation(s)
- Tianyou Zhou
- College of Social and Behavioral Sciences, Arizona State University, Glendale AZ, USA
| | - Jose E Náñez
- College of Social and Behavioral Sciences, Arizona State University, Glendale AZ, USA
| | - Daniel Zimmerman
- College of Social and Behavioral Sciences, Arizona State University, Glendale AZ, USA
| | - Steven R Holloway
- College of Social and Behavioral Sciences, Arizona State University, Glendale AZ, USA
| | - Aaron Seitz
- Department of Psychology, University of California, Riverside, Riverside CA, USA
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15
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Vidyasagar TR. Attentional Gating in Primary Visual Cortex: A Physiological Basis for Dyslexia. Perception 2016; 34:903-11. [PMID: 16178142 DOI: 10.1068/p5332] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The visual magnocellular pathway is known to play a central part in visuospatial attention and in directing attention to specific parts of the visual world in serial search. It is proposed that, in the case of reading, this mechanism is trained to perform a sequential gating of visual information coming into the primary visual cortex to enable further orderly processing by the ventral stream. This scheme, taken together with the potential for plasticity between the different afferent channels in the case of a relative impairment of the magnocellular system, can provide some limited rationale for the beneficial effects that have been claimed for the use of coloured overlays and glasses.
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Affiliation(s)
- Trichur R Vidyasagar
- Department of Optometry and Vision Sciences, University of Melbourne, Corner Keppel and Cardigan Streets, Carlton, VIC 3053, Australia.
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16
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Ahmadi K, Pouretemad HR, Esfandiari J, Yoonessi A, Yoonessi A. Psychophysical Evidence for Impaired Magno, Parvo, and Konio-cellular Pathways in Dyslexic Children. J Ophthalmic Vis Res 2016; 10:433-40. [PMID: 27051489 PMCID: PMC4795394 DOI: 10.4103/2008-322x.176911] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Purpose: Dyslexia is one of the most common learning disabilities affecting millions of people worldwide. Although exact causes of dyslexia are not well-known, a deficit in the magnocellular pathway may play a role. We examined possible deficiency of magnocellular, as compared to parvocellular and koniocellular pathway function by measuring luminance and color perception. Methods: Visual stimuli consisted of a series of natural images, divided into layers of luminance, red-green and blue-yellow, which probed magnocellular, parvocellular, and koniocellular pathways, respectively. Thirteen children with dyslexia and 13 sex- and age- matched controls performed three psychophysical tasks. In the first task, subjects were instructed to match the contrast of luminance (magno) and red-green (parvo) images to that of the blue-yellow (konio) images. In the second task, subjects detected the isoluminant point of red-green images to probe parvocellular pathway. In the third task, temporal processing was assessed by measuring reaction time and percentage of correct responses in an identification task using four categories of images, activating all three pathways. Results: The dyslexic group had significantly elevated luminance and color contrast thresholds and higher isoluminant point ratio in comparison to the control group. Furthermore, they had significantly less correct responses than the control group for the blue-yellow images. Conclusion: We may suggest that dyslexic subjects might suffer from both magnocellular and parvocellular deficits. Moreover, our results show partial impairment of the koniocellular pathway. Thus, dyslexia might be associated with deficits in all three visual pathways.
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Affiliation(s)
- Khazar Ahmadi
- Department of Psychology, Shahid Beheshti University, Tehran, Iran
| | - Hamid Reza Pouretemad
- Department of Psychology, Shahid Beheshti University, Tehran, Iran; Tehran-Oxford Neurodevelopmental Center, Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Tehran, Iran
| | | | - Ahmad Yoonessi
- Depatment of Ophthalmology, McGill Vision Research, McGill University, Montreal, QC, Canada
| | - Ali Yoonessi
- Neuropsychology Lab, Institute for Cognitive Science Studies, Tehran, Iran; Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
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17
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Skottun BC. On the use of spatial frequency to isolate contributions from the magnocellular and parvocellular systems and the dorsal and ventral cortical streams. Neurosci Biobehav Rev 2015; 56:266-75. [PMID: 26188134 DOI: 10.1016/j.neubiorev.2015.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 07/05/2015] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
Abstract
Many authors have claimed that suprathreshold achromatic stimuli of low and high spatial frequency can be used to separate responses from different entities in the visual system. Most prominently, it has been proposed that such stimuli can differentiate responses from the magnocellular and parvocellular systems. As is reviewed here, investigators who have examined stimulus specificity of neurons in these systems have found little difference between magno- and parvocellular cells. It has also been proposed that spatial frequency can be used to selectively activate the "magnocellular-dorsal stream". The present review indicates that cells in Area MT of the dorsal stream do prefer very low spatial frequencies. However, the review also shows that cells in Area V4 of the ventral stream respond, not only to relatively high spatial frequencies, but also to low frequency stimuli. Thus, low spatial frequencies cannot be relied upon to selectively activate the dorsal stream.
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18
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Kassaliete E, Lacis I, Fomins S, Krumina G. Reading and coherent motion perception in school age children. ANNALS OF DYSLEXIA 2015; 65:69-83. [PMID: 25911276 DOI: 10.1007/s11881-015-0099-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 03/04/2015] [Indexed: 06/04/2023]
Abstract
This study includes an evaluation, according to age, of the reading and global motion perception developmental trajectories of 2027 school age children in typical stages of development. Reading is assessed using the reading rate score test, for which all of the student participants, regardless of age, received the same passage of text of a medium difficulty reading level. The coherent motion perception threshold is determined according to the adaptive psychophysical protocol based on a four-alternative, forced-choice procedure. Three different dot velocities: 2, 5, and 8 deg/s were used for both assemblies of coherent or randomly moving dots. Reading rate score test results exhibit a wide dispersion across all age groups, so much so that the outlier data overlap, for both the 8 and 18-year-old student-participant age groups. Latvian children's reading fluency developmental trajectories reach maturation at 12-13 years of age. After the age of 13, reading rate scores increase slowly; however, the linear regression slope is different from zero and positive: F(1, 827) = 45.3; p < 0.0001. One hundred eighty-one student-participants having results below the 10th percentile were classified as weak readers in our study group. The reading fluency developmental trajectory of this particular group of student-participants does not exhibit any statistically significant saturation until the age of 18 years old. Coherent motion detection thresholds decrease with age and do not reach saturation. Tests with slower moving dots (2 deg/s) yield results that exhibit significant differences between strong and weak readers.
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Affiliation(s)
- Evita Kassaliete
- Department of Optometry and Vision Science, University of Latvia, 8Kengaraga Str., Riga, LV - 1063, Latvia,
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19
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Whitaker L, Jones CRG, Wilkins AJ, Roberson D. Judging the Intensity of Emotional Expression in Faces: the Effects of Colored Tints on Individuals With Autism Spectrum Disorder. Autism Res 2015; 9:450-9. [PMID: 26058998 DOI: 10.1002/aur.1506] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 05/07/2015] [Indexed: 11/09/2022]
Abstract
Individuals with autism spectrum disorder (ASD) often show atypical processing of facial expressions, which may result from visual stress. In the current study, children with ASD and matched controls judged which member of a pair of faces displayed the more intense emotion. Both faces showed anger, disgust, fear, happiness, sadness or surprise but to different degrees. Faces were presented on a monitor that was tinted either gray or with a color previously selected by the participant individually as improving the clarity of text. Judgments of emotional intensity improved significantly with the addition of the preferred colored tint in the ASD group but not in controls, a result consistent with a link between visual stress and impairments in processing facial expressions in individuals with ASD.
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Affiliation(s)
- Lydia Whitaker
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Catherine R G Jones
- School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff, United Kingdom
| | - Arnold J Wilkins
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Debi Roberson
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, United Kingdom
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20
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Kim JH, Seo HJ, Ha SG, Kim SH. Functional magnetic resonance imaging findings in Meares-Irlen syndrome: a pilot sudy. KOREAN JOURNAL OF OPHTHALMOLOGY 2015; 29:121-5. [PMID: 25829829 PMCID: PMC4369514 DOI: 10.3341/kjo.2015.29.2.121] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/13/2014] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To investigate patterns of functional magnetic resonance imaging (fMRI) activation during sentence reading before and after wearing color-tinted lenses. METHODS A total of 15 Meares-Irlen syndrome patients with a mean age of 23.4 years (range, 13 to 42 years) with no history of neurological or psychiatric disorders were scanned using a 3T MR scanner (Siemens, Tim-Trio, Germany). Each patient underwent two sessions of fMRI imaging (before and after MISViS color-tinted lens application). The fMRI paradigm included a block design of 20 seconds of rest (cross), 20 seconds of activation (sentence reading), and ten blocks (a total of 200 echo-planar image volumes) repeated for each session. Data preprocessing and analyses were performed using the SPM8 software package. RESULTS The reading speed of patients improved more than 20% while wearing the selected lenses. When compared to the before-lens session, the after-lens session identified significant regions of activation in the left middle and superior temporal gyri (paired t-test; maximal z score, 5.38; Montreal Neurological Institute coordinate, -60 / -39 / 0; threshold at p < 0.05; corrected for multiple comparisons using family-wise error). No region of activation at the same threshold was found in the before-lens session as compared to the after-lens session. CONCLUSIONS In the current study, we confirmed activation in the left middle and superior temporal gyri during sentence reading after wearing color-tinted lenses. These results could explain the effectiveness of color-tinted lenses in patients with Meares-Irlen syndrome.
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Affiliation(s)
- Ji Hyun Kim
- Department of Neurology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea
| | - Hye-Jin Seo
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Suk-Gyu Ha
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Seung-Hyun Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
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21
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Harries P, Perkins L, Parker C, Fowler L, Wignall S, Mangalpara E, Harries L. Supporting Children with Visual Stress: The Development of a Web Resource for Parents and Professionals. Br J Occup Ther 2014. [DOI: 10.4276/030802214x14176260335426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Introduction Visual stress is a condition which makes reading difficult. The use of coloured lenses in spectacles to alleviate the symptoms of visual stress has attracted increasing interest. The aim was to develop a web-based resource to centralize information about the condition and the processes for the screening, assessment, and provision of coloured lenses. Method Action research methods were employed. The exploratory phase used semi-structured interviews to gather parents' and professionals' views on the condition and their suggestions for the content and layout of a supporting web resource. The innovatory phase was used to design the prototype web resource. The evaluative phase was used to appraise and enhance the prototype website and collate data on website usage. Results Parents and professionals had some awareness of the condition but felt less sure of the evidence base for coloured lenses. Professionals valued research as evidence, whereas parents preferred testimonials. Suggestions for the content of a web resource to centralize information on the topic were clearly articulated by professionals, parents, and experts in the field. In the first year, over 7,500 individual web users visited the resource. Conclusion The first collaborative resource on the topic has been successfully produced, thereby offering a centralized information resource.
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Affiliation(s)
- Priscilla Harries
- Head of Department for Clinical Sciences, Brunel University London, London
| | - Lucy Perkins
- Former MSc Occupational Therapy student, Brunel University London, London
| | - Clare Parker
- Former MSc Occupational Therapy student, Brunel University London, London
| | - Lisa Fowler
- Former MSc Occupational Therapy student, Brunel University London, London
| | - Sharon Wignall
- Former MSc Occupational Therapy student, Brunel University London, London
| | - Esheeta Mangalpara
- Formerly BSc Biomedical Sciences student, Brunel University London, London
| | - Luke Harries
- Medical Student, St Catharine's College, Cambridge University, Cambridge
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22
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González-Castro P, Rodríguez C, Núñez JC, Vallejo G, González-Pienda JA. Altered visual sensory fusion in children with reading difficulties. Percept Mot Skills 2014; 119:925-48. [PMID: 25375826 DOI: 10.2466/15.10.pms.119c27z6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Reading is a multi-sensory and multi-cognitive task, and its difficulties (e.g., dyslexia) are not a unitary disorder. There are probably a variety of manifestations that relate to the actual site of impairment. A randomized, pre-test/post-test nonequivalent-groups design was conducted over 4 months with three groups aged between 6 and 8 years. One group comprised 76 participants (34 boys, 42 girls) with reading difficulties and altered sensory fusion (RD+ASF), a second group was made up of 123 students (59 boys, 64 girls) with reading difficulties but without altered sensory fusion (RD), and a third group comprised 81 participants (39 boys, 42 girls) who were young readers (RL) without reading delay, paired with the RD group on reading level. The experimental groups received intervention in the skills of control, stimulus recognition, and phonological awareness during a 4-month period. Both pre-test and post-test measures of errors in reading mechanics and reading routes (word and pseudo-word) were obtained. Poorer results in mechanics and reading routes of the RD+ASF group suggest that the effectiveness of the intervention depended on the characteristics of the groups and on the presence of sensory fusion deficits in the RD students.
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23
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Kunert R, Scheepers C. Speed and accuracy of dyslexic versus typical word recognition: an eye-movement investigation. Front Psychol 2014; 5:1129. [PMID: 25346708 PMCID: PMC4191135 DOI: 10.3389/fpsyg.2014.01129] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 09/17/2014] [Indexed: 11/13/2022] Open
Abstract
Developmental dyslexia is often characterized by a dual deficit in both word recognition accuracy and general processing speed. While previous research into dyslexic word recognition may have suffered from speed-accuracy trade-off, the present study employed a novel eye-tracking task that is less prone to such confounds. Participants (10 dyslexics and 12 controls) were asked to look at real word stimuli, and to ignore simultaneously presented non-word stimuli, while their eye-movements were recorded. Improvements in word recognition accuracy over time were modeled in terms of a continuous non-linear function. The words' rhyme consistency and the non-words' lexicality (unpronounceable, pronounceable, pseudohomophone) were manipulated within-subjects. Speed-related measures derived from the model fits confirmed generally slower processing in dyslexics, and showed a rhyme consistency effect in both dyslexics and controls. In terms of overall error rate, dyslexics (but not controls) performed less accurately on rhyme-inconsistent words, suggesting a representational deficit for such words in dyslexics. Interestingly, neither group showed a pseudohomophone effect in speed or accuracy, which might call the task-independent pervasiveness of this effect into question. The present results illustrate the importance of distinguishing between speed- vs. accuracy-related effects for our understanding of dyslexic word recognition.
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Affiliation(s)
- Richard Kunert
- Neurobiology of Language, Max Planck Institut für Psycholinguistik Nijmegen, Netherlands ; Neurobiology of Language, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Nijmegen, Netherlands
| | - Christoph Scheepers
- Institute of Neuroscience and Psychology, University of Glasgow Glasgow, Scotland
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24
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Romani C, Tsouknida E, Olson A. Encoding order and developmental dyslexia: a family of skills predicting different orthographic components. Q J Exp Psychol (Hove) 2014; 68:99-128. [PMID: 25246235 PMCID: PMC4409052 DOI: 10.1080/17470218.2014.938666] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We investigated order encoding in developmental dyslexia using a task that presented nonalphanumeric visual characters either simultaneously or sequentially--to tap spatial and temporal order encoding, respectively--and asked participants to reproduce their order. Dyslexic participants performed poorly in the sequential condition, but normally in the simultaneous condition, except for positions most susceptible to interference. These results are novel in demonstrating a selective difficulty with temporal order encoding in a dyslexic group. We also tested the associations between our order reconstruction tasks and: (a) lexical learning and phonological tasks; and (b) different reading and spelling tasks. Correlations were extensive when the whole group of participants was considered together. When dyslexics and controls were considered separately, different patterns of association emerged between orthographic tasks on the one side and tasks tapping order encoding, phonological processing, and written learning on the other. These results indicate that different skills support different aspects of orthographic processing and are impaired to different degrees in individuals with dyslexia. Therefore, developmental dyslexia is not caused by a single impairment, but by a family of deficits loosely related to difficulties with order. Understanding the contribution of these different deficits will be crucial to deepen our understanding of this disorder.
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Affiliation(s)
- Cristina Romani
- a School of Health and Life Sciences , Aston University , Birmingham , UK
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25
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Razuk M, Barela JA. Dyslexic children suffer from less informative visual cues to control posture. RESEARCH IN DEVELOPMENTAL DISABILITIES 2014; 35:1988-1994. [PMID: 24864051 DOI: 10.1016/j.ridd.2014.03.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 03/21/2014] [Accepted: 03/25/2014] [Indexed: 06/03/2023]
Abstract
The goal of this study was to investigate the effects of manipulation of the characteristics of visual stimulus on postural control in dyslexic children. A total of 18 dyslexic and 18 non-dyslexic children stood upright inside a moving room, as still as possible, and looked at a target at different conditions of distance between the participant and a moving room frontal wall (25-150 cm) and vision (full and central). The first trial was performed without vision (baseline). Then four trials were performed in which the room remained stationary and eight trials with the room moving, lasting 60s each. Mean sway amplitude, coherence, relative phase, and angular deviation were calculated. The results revealed that dyslexic children swayed with larger magnitude in both stationary and moving conditions. When the room remained stationary, all children showed larger body sway magnitude at 150 cm distance. Dyslexic children showed larger body sway magnitude in central compared to full vision condition. In the moving condition, body sway magnitude was similar between dyslexic and non-dyslexic children but the coupling between visual information and body sway was weaker in dyslexic children. Moreover, in the absence of peripheral visual cues, induced body sway in dyslexic children was temporally delayed regarding visual stimulus. Taken together, these results indicate that poor postural control performance in dyslexic children is related to how sensory information is acquired from the environment and used to produce postural responses. In conditions in which sensory cues are less informative, dyslexic children take longer to process sensory stimuli in order to obtain precise information, which leads to performance deterioration.
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Affiliation(s)
- Milena Razuk
- Graduate Program, Human Movement Science, Institute of Physical Activity and Sport Sciences, Cruzeiro do Sul University, São Paulo, SP, Brazil
| | - Jose A Barela
- Graduate Program, Human Movement Science, Institute of Physical Activity and Sport Sciences, Cruzeiro do Sul University, São Paulo, SP, Brazil; Institute of Biosciences, São Paulo State University, Rio Claro, SP, Brazil.
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26
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Neural correlates of language and non-language visuospatial processing in adolescents with reading disability. Neuroimage 2014; 101:653-66. [PMID: 25067812 DOI: 10.1016/j.neuroimage.2014.07.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/17/2014] [Accepted: 07/18/2014] [Indexed: 01/08/2023] Open
Abstract
Despite anecdotal evidence of relative visuospatial processing strengths in individuals with reading disability (RD), only a few studies have assessed the presence or the extent of these putative strengths. The current study examined the cognitive and neural bases of visuospatial processing abilities in adolescents with RD relative to typically developing (TD) peers. Using both cognitive tasks and functional magnetic resonance imaging (fMRI) we contrasted printed word recognition with non-language visuospatial processing tasks. Behaviorally, lower reading skill was related to a visuospatial processing advantage (shorter latencies and equivalent accuracy) on a geometric figure processing task, similar to findings shown in two published studies. FMRI analyses revealed key group by task interactions in patterns of cortical and subcortical activation, particularly in frontostriatal networks, and in the distributions of right and left hemisphere activation on the two tasks. The results are discussed in terms of a possible neural tradeoff in visuospatial processing in RD.
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27
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Stubenrauch C, Krinzinger H, Konrad K. [From brain imaging to good teaching? implicating from neuroscience for research on learning and instruction]. ZEITSCHRIFT FUR KINDER-UND JUGENDPSYCHIATRIE UND PSYCHOTHERAPIE 2014; 42:253-68; quiz 268-9. [PMID: 25005903 DOI: 10.1024/1422-4917/a000298] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Psychiatric disorders in childhood and adolescence, in particular attention deficit disorder or specific learning disorders like developmental dyslexia and developmental dyscalculia, affect academic performance and learning at school. Recent advances in neuroscientific research have incited an intensive debate both in the general public and in the field of educational and instructional science as well as to whether and to what extent these new findings in the field of neuroscience might be of importance for school-related learning and instruction. In this review, we first summarize neuroscientific findings related to the development of attention, working memory and executive functions in typically developing children and then evaluate their relevance for school-related learning. We present an overview of neuroimaging studies of specific learning disabilities such as developmental dyslexia and developmental dyscalculia, and critically discuss their practical implications for educational and teaching practice, teacher training, early diagnosis as well as prevention and disorder-specific therapy. We conclude that the new interdisciplinary field of neuroeducation cannot be expected to provide direct innovative educational applications (e.g., teaching methods). Rather, the future potential of neuroscience lies in creating a deeper understanding of the underlying cognitive mechanisms and pathomechanisms of learning processes and learning disorders.
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Affiliation(s)
- Christa Stubenrauch
- Kinder- und Jugendabteilung für Psychische Gesundheit, Universitätsklinikum Erlangen
| | - Helga Krinzinger
- Lehr- und Forschungsgebiet Klinische Neuropsychologie des Kindes- und Jugendalters, Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum der RWTH Aachen
| | - Kerstin Konrad
- Lehr- und Forschungsgebiet Klinische Neuropsychologie des Kindes- und Jugendalters, Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum der RWTH Aachen Kognitive Entwicklung, Institut für Neurowissenschaften und Medizin (INM-III), Forschungszentrum Jülich
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28
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Conlon EG, Lilleskaret G, Wright CM, Stuksrud A. Why do adults with dyslexia have poor global motion sensitivity? Front Hum Neurosci 2013; 7:859. [PMID: 24376414 PMCID: PMC3860316 DOI: 10.3389/fnhum.2013.00859] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 11/25/2013] [Indexed: 12/01/2022] Open
Abstract
Two experiments aimed to determine why adults with dyslexia have higher global motion thresholds than typically reading controls. In Experiment 1, the dot density and number of animation frames presented in the dot stimulus were manipulated because of findings that use of a high dot density can normalize coherence thresholds in individuals with dyslexia. Dot densities were 14.15 and 3.54 dots/deg2. These were presented for five (84 ms) or eight (134 ms) frames. The dyslexia group had higher coherence thresholds in all conditions than controls. However, in the high dot density, long duration condition, both reader groups had the lowest thresholds indicating normal temporal recruitment. These results indicated that the dyslexia group could sample the additional signals dots over space and then integrate these with the same efficiency as controls. In Experiment 2, we determined whether briefly presenting a fully coherent prime moving in either the same or opposite direction of motion to a partially coherent test stimulus would systematically increase and decrease global motion thresholds in the reader groups. When the direction of motion in the prime and test was the same, global motion thresholds increased for both reader groups. The increase in coherence thresholds was significantly greater for the dyslexia group. When the motion of the prime and test were presented in opposite directions, coherence thresholds were reduced in both groups. No group threshold differences were found. We concluded that the global motion processing deficit found in adults with dyslexia can be explained by undersampling of the target motion signals. This might occur because of difficulties directing attention to the relevant motion signals in the random dot pattern, and not a specific difficulty integrating global motion signals. These effects are most likely to occur in the group with dyslexia when more complex computational processes are required to process global motion.
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Affiliation(s)
- Elizabeth G Conlon
- Griffith Health Institute, School of Applied Psychology, Griffith University Gold Coast, QLD, Australia
| | - Gry Lilleskaret
- Griffith Health Institute, School of Applied Psychology, Griffith University Gold Coast, QLD, Australia
| | - Craig M Wright
- Griffith Health Institute, School of Applied Psychology, Griffith University Gold Coast, QLD, Australia
| | - Anne Stuksrud
- Griffith Health Institute, School of Applied Psychology, Griffith University Gold Coast, QLD, Australia
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29
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Danelli L, Berlingeri M, Bottini G, Ferri F, Vacchi L, Sberna M, Paulesu E. Neural intersections of the phonological, visual magnocellular and motor/cerebellar systems in normal readers: implications for imaging studies on dyslexia. Hum Brain Mapp 2013; 34:2669-87. [PMID: 22736513 PMCID: PMC6870382 DOI: 10.1002/hbm.22098] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 03/14/2012] [Accepted: 03/15/2012] [Indexed: 01/27/2023] Open
Abstract
We used fMRI to explore the extent of the anatomical overlap of three neural systems that the literature on developmental dyslexia associates with reading: the auditory phonological, the visual magnocellular, and the motor/cerebellar systems. Twenty-eight normal subjects performed four tasks during fMRI scans: word and pseudoword reading, auditory rhyming for letter names, visual motion perception, and a motor sequence learning task. We found that the left occipitotemporal cortex (OTC), which previous studies reported to be dysfunctional in dyslexia, can be fractionated into different functional areas: an anterior and lateral area that was activated by both reading and auditory rhyming tasks; a posterior area that was commonly activated by both the reading and the motion perception task and a medial/intermediate area, including the so-called Visual Word Form Area, which was specifically activated by the reading task. These results show that the left OTC is an area of segregated convergence of different functional systems. We compared our results with the hypoactivation pattern reported for reading in a previous cross-cultural PET study on 36 dyslexic subjects from three countries. The region of decreased activation in dyslexia overlapped with regions that are specific for reading and those activated during both the auditory rhyming task and the single word and pseudoword reading task described in the present fMRI study. No overlap was found with the activation patterns for the visual motion perception task or for the motor sequence learning task. These observations challenge current theories of dyslexia.
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Affiliation(s)
- Laura Danelli
- Psychology Department, University of Milano-Bicocca, Milan, Italy
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30
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Landi N, Frost SJ, Menc WE, Sandak R, Pugh KR. Neurobiological bases of reading comprehension: Insights from neuroimaging studies of word level and text level processing in skilled and impaired readers. READING & WRITING QUARTERLY : OVERCOMING LEARNING DIFFICULTIES 2013; 29:145-167. [PMID: 23662034 PMCID: PMC3646421 DOI: 10.1080/10573569.2013.758566] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
For accurate reading comprehension, readers must first learn to map letters to their corresponding speech sounds and meaning and then they must string the meanings of many words together to form a representation of the text. Furthermore, readers must master the complexities involved in parsing the relevant syntactic and pragmatic information necessary for accurate interpretation. Failure in this process can occur at multiple levels and cognitive neuroscience has been helpful in identifying the underlying causes of success and failure in reading single words and in reading comprehension. In general, neurobiological studies of skilled reading comprehension indicate a highly overlapping language circuit for single word reading, reading comprehension and listening comprehension with largely quantitative differences in a number of reading and language related areas. This paper reviews relevant research from studies employing neuroimaging techniques to study reading with a focus on the relationship between reading skill, single word reading, and text comprehension.
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Affiliation(s)
- Nicole Landi
- University of Minnesota, Department of Educational Psychology, Minneapolis, MN
- Haskins Laboratories, New Haven, CT
| | | | - W. Einar Menc
- University of Minnesota, Department of Educational Psychology, Minneapolis, MN
- Haskins Laboratories, New Haven, CT
| | | | - Kenneth R. Pugh
- Haskins Laboratories, New Haven, CT
- Yale University School of Medicine, Department of Pediatrics, New Haven, CT
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31
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van Ermingen-Marbach M, Grande M, Pape-Neumann J, Sass K, Heim S. Distinct neural signatures of cognitive subtypes of dyslexia with and without phonological deficits. NEUROIMAGE-CLINICAL 2013; 2:477-90. [PMID: 24936406 PMCID: PMC4054964 DOI: 10.1016/j.nicl.2013.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 03/08/2013] [Accepted: 03/16/2013] [Indexed: 01/23/2023]
Abstract
Developmental dyslexia can be distinguished as different cognitive subtypes with and without phonological deficits. However, despite some general agreement on the neurobiological basis of dyslexia, the neurofunctional mechanisms underlying these cognitive subtypes remain to be identified. The present BOLD fMRI study thus aimed at investigating by which distinct and/or shared neural activation patterns dyslexia subtypes are characterized. German dyslexic fourth graders with and without deficits in phonological awareness and age-matched normal readers performed a phonological decision task: does the auditory word contain the phoneme/a/? Both dyslexic subtypes showed increased activation in the right cerebellum (Lobule IV) compared to controls. Subtype-specific increased activation was systematically found for the phonological dyslexics as compared to those without this deficit and controls in the left inferior frontal gyrus (area 44: phonological segmentation), the left SMA (area 6), the left precentral gyrus (area 6) and the right insula. Non-phonological dyslexics revealed subtype-specific increased activation in the left supramarginal gyrus (area PFcm; phonological storage) and angular gyrus (area PGp). The study thus provides the first direct evidence for the neurobiological grounding of dyslexia subtypes. Moreover, the data contribute to a better understanding of the frequently encountered heterogeneous neuroimaging results in the field of dyslexia.
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Affiliation(s)
- Muna van Ermingen-Marbach
- Section Structural-Functional Brain Mapping, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Germany ; JARA-Translational Brain Medicine, Germany
| | - Marion Grande
- Section Neurological Cognition Research, Department of Neurology, Medical School, RWTH Aachen University, Germany
| | - Julia Pape-Neumann
- Section Neurological Cognition Research, Department of Neurology, Medical School, RWTH Aachen University, Germany
| | - Katharina Sass
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Germany ; JARA-Translational Brain Medicine, Germany
| | - Stefan Heim
- Section Structural-Functional Brain Mapping, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Germany ; Section Neurological Cognition Research, Department of Neurology, Medical School, RWTH Aachen University, Germany ; Research Centre Jülich, Institute of Neuroscience and Medicine (INM-1), Germany ; JARA-Translational Brain Medicine, Germany
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32
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Crutch SJ. Seeing why they cannot see: Understanding the syndrome and causes of posterior cortical atrophy. J Neuropsychol 2013; 8:157-70. [DOI: 10.1111/jnp.12011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 01/07/2013] [Indexed: 12/11/2022]
Affiliation(s)
- Sebastian J. Crutch
- Dementia Research Centre; Department of Neurodegeneration; UCL Institute of Neurology; University College London; UK
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33
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Palomo-Álvarez C, Puell MC. Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties. Graefes Arch Clin Exp Ophthalmol 2012; 251:945-51. [PMID: 23011002 DOI: 10.1007/s00417-012-2162-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 09/10/2012] [Accepted: 09/13/2012] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties. METHODS A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3-6 (aged 9-11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n = 46) and a without-treatment group (n = 36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed. RESULTS Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p = 0.01). CONCLUSION No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.
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34
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Loew SJ, Watson K. A Prospective Genetic Marker of the Visual-Perception Disorder Meares-Irlen Syndrome. Percept Mot Skills 2012; 114:870-82. [DOI: 10.2466/24.10.11.27.pms.114.3.870-882] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prior investigations of scotopic sensitivity or Meares-Irlen syndrome have identified several features also found in attention deficit/hyperactivity disorder, chronic fatigue syndrome, and a subtype of dyslexia in which visual recognition is the primary deficit. In particular, anomalies in lipid metabolism, including low essential fatty acid status and decreased serum cholesterol, have been identified in all three disorders. Genetic expression of the transporter molecule apolipoprotein B-100 (APOB) has been correlated with abnormal lipid metabolism, particularly in relation to levels of cholesterol. Cholesterol esters are important carriers of essential fatty acids entering the retina. The APOB gene coding for apolipoprotein B-100 is located on the short arm of Chromosome 2, and closely neighbours a gene (DYX3) known to confer susceptibility to dyslexia. The APOB locus is also recognised as being one of the most highly polymorphic regions of the human genome, and thus provides a promising tool for genetic researchers. In this pilot study, certain allelic variants of the APOB gene were more common in participants diagnosed with Meares–Irlen syndrome than in individuals without the condition. This study appears to be a first in which a condition known to cause reading difficulties has been associated with the APOB gene.
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Affiliation(s)
- Stephen J Loew
- Centre for Bioactive Discovery in Health and Ageing, School of Science & Technology, University of New England, Armidale, Australia
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Li W, Meekins K, Schirillo J. Magno and parvo stimuli affect illusory directional hearing in normal and dyslexic readers. Neuropsychologia 2012; 50:2068-74. [PMID: 22609575 DOI: 10.1016/j.neuropsychologia.2012.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/06/2012] [Indexed: 11/28/2022]
Abstract
In an experimental paradigm adapted from Hari (1995), forty observers listened via headphones to 8 binaural clicks: 4 left-ear leading followed by 4 right-ear leading with either 38 or 140 ms interstimulus intervals (ISIs). Concurrently, they viewed either foveal or peripheral visual stimuli designed to activate either the parvocellular or magnocellular pathway. They then reported the perceived location of each click-pair. Our results replicated Hari's finding that observers mistake the perceived location of short ISI click-pairs more often than long. That is, when ISIs were short, the sounds seemed to play across the inside of the head in a phenomenon called illusory directional hearing. However, when click-pairs were accompanied by peripheral visual stimuli that activated the magnocellular pathway, observers were more accurate than when there were no visual stimuli. Conversely, parvocellular-activating foveal visual stimuli produced more illusory hearing than when there were no visual stimuli. These findings suggest that activating the slow sustained parvocellular system may result in a longer processing window. Thirty dyslexic observers who repeated the experimental paradigm had an even longer processing window than control observers indicating that dyslexics may have a magnocellular system deficit.
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Affiliation(s)
- Winston Li
- Department of Psychology, Wake Forest University, Winston-Salem, NC 27109, USA
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Peyrin C, Lallier M, Démonet JF, Pernet C, Baciu M, Le Bas JF, Valdois S. Neural dissociation of phonological and visual attention span disorders in developmental dyslexia: FMRI evidence from two case reports. BRAIN AND LANGUAGE 2012; 120:381-394. [PMID: 22285025 DOI: 10.1016/j.bandl.2011.12.015] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 09/23/2011] [Accepted: 12/24/2011] [Indexed: 05/31/2023]
Abstract
A dissociation between phonological and visual attention (VA) span disorders has been reported in dyslexic children. This study investigates whether this cognitively-based dissociation has a neurobiological counterpart through the investigation of two cases of developmental dyslexia. LL showed a phonological disorder but preserved VA span whereas FG exhibited the reverse pattern. During a phonological rhyme judgement task, LL showed decreased activation of the left inferior frontal gyrus whereas this region was activated at the level of the controls in FG. Conversely, during a visual categorization task, FG demonstrated decreased activation of the parietal lobules whereas these regions were activated in LL as in the controls. These contrasted patterns of brain activation thus mirror the cognitive disorders' dissociation. These findings provide the first evidence for an association between distinct brain mechanisms and distinct cognitive deficits in developmental dyslexia, emphasizing the importance of taking into account the heterogeneity of the reading disorder.
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Affiliation(s)
- C Peyrin
- CNRS UMR 5105, 38040 Grenoble, France.
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Cloning and identification of a novel C18-Δ9 polyunsaturated fatty acid specific elongase gene from DHA-producing Isochrysis galbana H29. BIOTECHNOL BIOPROC E 2012. [DOI: 10.1007/s12257-011-0037-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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38
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de Boer-Schellekens L, Vroomen J. Sound can improve visual search in developmental dyslexia. Exp Brain Res 2012; 216:243-8. [PMID: 22064932 PMCID: PMC3258400 DOI: 10.1007/s00221-011-2926-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 10/23/2011] [Indexed: 11/28/2022]
Abstract
We examined whether developmental dyslexic adults suffer from sluggish attentional shifting (SAS; Hari and Renvall in Trends Cogn Sci 5:525-532, 2001) by measuring their shifting of attention in a visual search task with dynamic cluttered displays (Van der Burg et al. in J Exp Psychol Human 34:1053-1065, 2008). Dyslexics were generally slower than normal readers in searching a horizontal or vertical target among oblique distracters. However, the addition of a click sound presented in synchrony with a color change of the target drastically improved their performance up to the level of the normal readers. These results are in line with the idea that developmental dyslexics have specific problems in disengaging attention from the current fixation, and that the phasic alerting by a sound can compensate for this deficit.
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Affiliation(s)
| | - Jean Vroomen
- Department of Psychology, Tilburg University, P.O. Box 90153, 5000 LE Tilburg, The Netherlands
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39
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Ruland A, Willmes K, Günther T. Zusammenhang zwischen Aufmerksamkeitsdefiziten und Lese-Rechtschreibschwäche. KINDHEIT UND ENTWICKLUNG 2012. [DOI: 10.1026/0942-5403/a000053] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Neben anderen Voraussetzungen sind beim Lese- und Rechtschreiberwerb Aufmerksamkeitsprozesse essentiell. In der vorliegenden Studie wurde modellorientiert erfasst, in welchen Teilkomponenten der Aufmerksamkeit Kinder mit einer Lese- Rechtschreibstörung (LRS) auffällig sind. Dazu wurden 32 Kinder mit einer LRS aus dem dritten und vierten Schuljahr mit 31 Kontrollkindern verglichen. Alle Kinder führten computergestützte Aufmerksamkeitsaufgaben durch, mit denen Intensitätsaspekte, Selektivitätsaspekte, Kontrollfunktionen und räumliche Ausrichtung der Aufmerksamkeit überprüft wurden. Es zeigte sich, dass Defizite im Lesen und Schreiben mit Leistungen im Bereich der Aufmerksamkeit korrelieren. Im Vergleich zur Kontrollgruppe konnten Defizite für Intensitätsaspekte der Aufmerksamkeit, räumliche Aufmerksamkeitsaspekte und kontrollierende Aufmerksamkeitsfunktionen festgestellt werden. Schlussfolgernd sprechen die Ergebnisse dafür, dass eine LRS mit Defiziten in der Aufmerksamkeit assoziiert ist.
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Affiliation(s)
- Anne Ruland
- Klinik für Neurologie des Universitätsklinikums der RWTH Aachen
- School of Speech and Language Therapy, Zuyd University, Heerlen
| | - Klaus Willmes
- Klinik für Neurologie des Universitätsklinikums der RWTH Aachen
| | - Thomas Günther
- School of Speech and Language Therapy, Zuyd University, Heerlen
- Lehr- und Forschungsgebiet für klinische Neuropsychologie des Kindes- und Jugendalters, Universitätsklinikum der RWTH Aachen
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A Functional Neuroimaging Case Study of Meares–Irlen Syndrome/Visual Stress (MISViS). Brain Topogr 2011; 25:293-307. [PMID: 22124535 DOI: 10.1007/s10548-011-0212-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 11/14/2011] [Indexed: 10/15/2022]
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41
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de Boer-Schellekens L, Vroomen J. Sound can improve visual search in developmental dyslexia. Exp Brain Res 2011. [PMID: 22064932 DOI: 10.1007/s00221-011-2926-2"] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We examined whether developmental dyslexic adults suffer from sluggish attentional shifting (SAS; Hari and Renvall in Trends Cogn Sci 5:525-532, 2001) by measuring their shifting of attention in a visual search task with dynamic cluttered displays (Van der Burg et al. in J Exp Psychol Human 34:1053-1065, 2008). Dyslexics were generally slower than normal readers in searching a horizontal or vertical target among oblique distracters. However, the addition of a click sound presented in synchrony with a color change of the target drastically improved their performance up to the level of the normal readers. These results are in line with the idea that developmental dyslexics have specific problems in disengaging attention from the current fixation, and that the phasic alerting by a sound can compensate for this deficit.
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42
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Rauschecker AM, Bowen RF, Perry LM, Kevan AM, Dougherty RF, Wandell BA. Visual feature-tolerance in the reading network. Neuron 2011; 71:941-53. [PMID: 21903085 DOI: 10.1016/j.neuron.2011.06.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2011] [Indexed: 11/17/2022]
Abstract
A century of neurology and neuroscience shows that seeing words depends on ventral occipital-temporal (VOT) circuitry. Typically, reading is learned using high-contrast line-contour words. We explored whether a specific VOT region, the visual word form area (VWFA), learns to see only these words or recognizes words independent of the specific shape-defining visual features. Word forms were created using atypical features (motion-dots, luminance-dots) whose statistical properties control word-visibility. We measured fMRI responses as word form visibility varied, and we used TMS to interfere with neural processing in specific cortical circuits, while subjects performed a lexical decision task. For all features, VWFA responses increased with word-visibility and correlated with performance. TMS applied to motion-specialized area hMT+ disrupted reading performance for motion-dots, but not line-contours or luminance-dots. A quantitative model describes feature-convergence in the VWFA and relates VWFA responses to behavioral performance. These findings suggest how visual feature-tolerance in the reading network arises through signal convergence from feature-specialized cortical areas.
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Affiliation(s)
- Andreas M Rauschecker
- Neurosciences Program and Medical Scientist Training Program, Stanford School of Medicine, Stanford University, Stanford, CA 94305, USA.
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Abstract
This review summarizes recent ideas about the cortical circuits for seeing words, an important part of the brain system for reading. Historically, the link between the visual cortex and reading has been contentious. One influential position is that the visual cortex plays a minimal role, limited to identifying contours, and that information about these contours is delivered to cortical regions specialized for reading and language. An alternative position is that specializations for seeing words develop within the visual cortex itself. Modern neuroimaging measurements-including both functional magnetic resonance imaging (fMRI) and diffusion weighted imaging with tractography (DTI) data-support the position that circuitry for seeing the statistical regularities of word forms develops within the ventral occipitotemporal cortex, which also contains important circuitry for seeing faces, colors, and forms. This review explains new findings about the visual pathways, including visual field maps, as well as new findings about how we see words. The measurements from the two fields are in close cortical proximity, and there are good opportunities for coordinating theoretical ideas about function in the ventral occipitotemporal cortex.
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Affiliation(s)
- Brian A Wandell
- Psychology Department, Stanford University, Stanford, California
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Huestegge L, Heim S, Zettelmeyer E, Lange-Küttner C. Gender-specific contribution of a visual cognition network to reading abilities. Br J Psychol 2011; 103:117-28. [PMID: 22229778 DOI: 10.1111/j.2044-8295.2011.02050.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lynn Huestegge
- Institute of Psychology, Rheinisch-Westfälische Technische Hochschule (RWTH Aachen University), Aachen, Germany
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45
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Isolation of a novel C18-Δ9 polyunsaturated fatty acid specific elongase gene from DHA-producing Isochrysis galbana H29 and its use for the reconstitution of the alternative Δ8 pathway in Saccharomyces cerevisiae. Biotechnol Lett 2011; 33:1823-30. [DOI: 10.1007/s10529-011-0626-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 04/08/2011] [Indexed: 10/18/2022]
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Abstract
Apresentamos a Psicofísica como uma ciência aplicada nas investigações e nas abordagens e diagnósticos clínicos. Inicialmente, introduzimos algo dos aspectos epistemológicos e teóricos da área, passamos para as abordagens que a Psicofísica pode apresentar na aplicabilidade clínica e, por fim, discutimos os avanços recentes da aplicação clínica, apresentamos as experiências de nosso laboratório de pesquisa clínica em psicofísica, finalizando com as perspectivas de ampliação do uso da psicofísica para investigações clínicas de funções perceptuais mais complexas.
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Boets B, Vandermosten M, Cornelissen P, Wouters J, Ghesquière P. Coherent Motion Sensitivity and Reading Development in the Transition From Prereading to Reading Stage. Child Dev 2011; 82:854-69. [DOI: 10.1111/j.1467-8624.2010.01527.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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48
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CHRISTIAN SKOTTUN BERNT. ON THE USE OF VISUAL MOTION PERCEPTION TO ASSESS MAGNOCELLULAR INTEGRITY. J Integr Neurosci 2011; 10:15-32. [DOI: 10.1142/s0219635211002592] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 10/20/2010] [Indexed: 11/18/2022] Open
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49
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Hatzidaki A, Gianneli M, Petrakis E, Makaronas N, Aslanides IM. Reading and visual processing in Greek dyslexic children: an eye-movement study. DYSLEXIA (CHICHESTER, ENGLAND) 2011; 17:85-104. [PMID: 20799263 DOI: 10.1002/dys.416] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We examined the impact of the effects of dyslexia on various processing and cognitive components (e.g., reading speed and accuracy) in a language with high phonological and orthographic consistency. Greek dyslexic children were compared with a chronological age-matched group on tasks that tested participants' phonological and orthographic awareness during reading and spelling, as well as their efficiency to detect a specific target-letter during a sequential visual search task. Dyslexic children showed impaired reading and spelling that was reflected in slow reading speed and error-prone performance, especially for non-words. Eye movement measures of text reading also provided supporting evidence for a reading deficit, with dyslexic participants producing more fixations and longer fixation duration as opposed to non-dyslexic participants. The results of the visual search task showed similar performance between the two groups, but when they were compared with the results of text reading, dyslexic participants were found to be able to process fewer stimuli (i.e., letters) at each fixation than non-dyslexics. Our findings further suggest that, although Greek dyslexics have the advantage of a consistent orthographic system which facilitates acquisition of reading and phonological awareness, they demonstrate more impaired access to orthographic forms than dyslexics of other transparent orthographies.
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Crutch SJ, Lehmann M, Gorgoraptis N, Kaski D, Ryan N, Husain M, Warrington EK. Abnormal visual phenomena in posterior cortical atrophy. Neurocase 2011; 17:160-77. [PMID: 20818540 DOI: 10.1080/13554794.2010.504729] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Individuals with posterior cortical atrophy (PCA) report a host of unusual and poorly explained visual disturbances. This preliminary report describes a single patient (CRO), and documents and investigates abnormally prolonged colour afterimages (concurrent and prolonged perception of colours complimentary to the colour of an observed stimulus), perceived motion of static stimuli, and better reading of small than large letters. We also evaluate CRO's visual and vestibular functions in an effort to understand the origin of her experience of room tilt illusion, a disturbing phenomenon not previously observed in individuals with cortical degenerative disease. These visual symptoms are set in the context of a 4-year longitudinal neuropsychological and neuroimaging investigation of CRO's visual and other cognitive skills. We hypothesise that prolonged colour after-images are attributable to relative sparing of V1 inhibitory interneurons; perceived motion of static stimuli reflects weak magnocellular function; better reading of small than large letters indicates a reduced effective field of vision; and room tilt illusion effects are caused by disordered integration of visual and vestibular information. This study contributes to the growing characterisation of PCA whose atypical early visual symptoms are often heterogeneous and frequently under-recognised.
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Affiliation(s)
- Sebastian J Crutch
- Dementia Research Centre, Department of Neurodegeneration, UCL Institute of Neurology, University College London, UK.
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