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Hirshorn EA, Harris LN. Culture is not destiny, for reading: highlighting variable routes to literacy within writing systems. Ann N Y Acad Sci 2022; 1513:31-47. [PMID: 35313016 DOI: 10.1111/nyas.14768] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 02/17/2022] [Indexed: 01/17/2023]
Abstract
Cross-writing system research in psychology and cognitive neuroscience has yielded important findings regarding how a writing system's structure can influence the cognitive challenges of learning to read and the neural underpinnings of literacy. The current paper reviews these differences and extends the findings to demonstrate diversity in how skilled reading is accomplished within a single writing system, English. We argue that broad clusters of behavioral and neural patterns found across writing systems can also be found within subpopulations who display atypical routes to skilled English reading, subpopulations including Chinese-English bilinguals, deaf native signers, compensated readers, and distortion-sensitive readers. The patterns of interest include a tradeoff between the degree of reliance on phonological and morphological processing for skilled reading, a shift in attentional focus from smaller to larger orthographic units, and enhanced bilaterality of neural processing during word reading. Lastly, we consider how understanding atypical routes to reading may apply to other writing systems.
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Affiliation(s)
| | - Lindsay N Harris
- Department of Leadership, Educational Psychology and Foundations, Northern Illinois University, DeKalb, Illinois
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2
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Johns CL, Jahn AA, Jones HR, Kush D, Molfese PJ, Van Dyke JA, Magnuson JS, Tabor W, Mencl WE, Shankweiler DP, Braze D. Individual differences in decoding skill, print exposure, and cortical structure in young adults. LANGUAGE, COGNITION AND NEUROSCIENCE 2018; 33:1275-1295. [PMID: 30505876 PMCID: PMC6258201 DOI: 10.1080/23273798.2018.1476727] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 05/04/2018] [Indexed: 06/09/2023]
Abstract
This exploratory study investigated relations between individual differences in cortical grey matter structure and young adult readers' cognitive profiles. Whole-brain analyses revealed neuroanatomical correlations with word and nonword reading ability (decoding), and experience with printed matter. Decoding was positively correlated with grey matter volume (GMV) in left superior temporal sulcus, and thickness (GMT) in right superior temporal gyrus. Print exposure was negatively correlated with GMT in left inferior frontal gyrus (pars opercularis) and left fusiform gyrus (including the visual word form area). Both measures also correlated with supramarginal gyrus (SMG), but in spatially distinct subregions: decoding was positively associated with GMV in left anterior SMG, and print exposure was negatively associated with GMT in left posterior SMG. Our comprehensive approach to assessment both confirms and refines our understanding of the novel relation between the structure of pSMG and proficient reading, and unifies previous research relating cortical structure and reading skill.
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Affiliation(s)
- Clinton L. Johns
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
| | - Andrew A. Jahn
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
| | - Hannah R. Jones
- Department of Clinical and Social Sciences in Psychology, University of Rochester, Melora Hall, P.O. Box 270266, Rochester, NY, 14627-0266, U.S.A
| | - Dave Kush
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Department of Language and Literature, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Peter J. Molfese
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institutes of Mental Health, National Institutes of Health, Department of Health and Human Services
| | - Julie A. Van Dyke
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT, 06269-1272, U.S.A
| | - James S. Magnuson
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Department of Psychological Sciences, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269-1020, U.S.A
- Brain Imaging Research Center, University of Connecticut, 850 Bolton Road, Unit 1271, Storrs, CT, 06269-1271, U.S.A
- Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT, 06269-1272, U.S.A
| | - Whitney Tabor
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Department of Psychological Sciences, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269-1020, U.S.A
- Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT, 06269-1272, U.S.A
| | - W. Einar Mencl
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
| | - Donald P. Shankweiler
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Department of Psychological Sciences, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT, 06269-1020, U.S.A
| | - David Braze
- Haskins Laboratories, 300 George St., Suite 900, New Haven, CT, 06511, U.S.A
- Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT, 06269-1272, U.S.A
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3
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Wiseheart R, Altmann LJP. Spoken sentence production in college students with dyslexia: working memory and vocabulary effects. INTERNATIONAL JOURNAL OF LANGUAGE & COMMUNICATION DISORDERS 2018; 53:355-369. [PMID: 29159849 DOI: 10.1111/1460-6984.12353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 09/19/2017] [Accepted: 09/29/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Individuals with dyslexia demonstrate syntactic difficulties on tasks of language comprehension, yet little is known about spoken language production in this population. AIMS To investigate whether spoken sentence production in college students with dyslexia is less proficient than in typical readers, and to determine whether group differences can be attributable to cognitive differences between groups. METHODS & PROCEDURES Fifty-one college students with and without dyslexia were asked to produce sentences from stimuli comprising a verb and two nouns. Verb types varied in argument structure and morphological form and nouns varied in animacy. Outcome measures were precision (measured by fluency, grammaticality and completeness) and efficiency (measured by response times). Vocabulary and working memory tests were also administered and used as predictors of sentence production performance. OUTCOMES & RESULTS Relative to non-dyslexic peers, students with dyslexia responded significantly slower and produced sentences that were significantly less precise in terms of fluency, grammaticality and completeness. The primary predictors of precision and efficiency were working memory, which differed between groups, and vocabulary, which did not. CONCLUSIONS & IMPLICATIONS College students with dyslexia were significantly less facile and flexible on this spoken sentence-production task than typical readers, which is consistent with previous studies of school-age children with dyslexia. Group differences in performance were traced primarily to limited working memory, and were somewhat mitigated by strong vocabulary.
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Affiliation(s)
- Rebecca Wiseheart
- St. John's University, Communication Sciences and Disorders, Queens, NY, USA
| | - Lori J P Altmann
- University of Florida, Speech, Language, and Hearing Sciences, Gainesville, FL, USA
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Ramus F, Altarelli I, Jednoróg K, Zhao J, Scotto di Covella L. Neuroanatomy of developmental dyslexia: Pitfalls and promise. Neurosci Biobehav Rev 2017; 84:434-452. [PMID: 28797557 DOI: 10.1016/j.neubiorev.2017.08.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 07/28/2017] [Accepted: 08/02/2017] [Indexed: 01/18/2023]
Abstract
Investigations into the neuroanatomical bases of developmental dyslexia have now spanned more than 40 years, starting with the post-mortem examination of a few individual brains in the 60s and 70s, and exploding in the 90s with the widespread use of MRI. The time is now ripe to reappraise the considerable amount of data gathered with MRI using different types of sequences (T1, diffusion, spectroscopy) and analysed using different methods (manual, voxel-based or surface-based morphometry, fractional anisotropy and tractography, multivariate analyses…). While selective reviews of mostly small-scale studies seem to provide a coherent view of the brain disruptions that are typical of dyslexia, involving left perisylvian and occipito-temporal regions, we argue that this view may be deceptive and that meta-analyses and large-scale studies rather highlight many inconsistencies and limitations. We discuss problems inherent to small sample size as well as methodological difficulties that still undermine the discovery of reliable neuroanatomical bases of dyslexia, and we outline some recommendations to further improve this research area.
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Affiliation(s)
- Franck Ramus
- Laboratoire de sciences cognitives et psycholinguistique (CNRS, ENS, EHESS, PSL Research University), Ecole Normale Supérieure, 29 rue d'Ulm, 75005 Paris, France.
| | - Irene Altarelli
- Brain and Learning Lab, Campus Biotech, University of Geneva, 9 Chemin des Mines, 1205 Geneva, Switzerland
| | - Katarzyna Jednoróg
- Laboratory of Psychophysiology, Department of Neurophysiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093 Warsaw, Poland
| | - Jingjing Zhao
- School of Psychology, Shaanxi Normal University and Key Laboratory for Behavior and Cognitive Neuroscience of Shaanxi Province, Xi'an, Shaanxi, 710062, China
| | - Lou Scotto di Covella
- Laboratoire de sciences cognitives et psycholinguistique (CNRS, ENS, EHESS, PSL Research University), Ecole Normale Supérieure, 29 rue d'Ulm, 75005 Paris, France
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5
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Kang JG, Lee SH, Park EJ, Leem HS. Event-related Potential Patterns Reflect Reversed Hemispheric Activity during Visual Attention Processing in Children with Dyslexia: A Preliminary Study. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE 2016; 14:33-42. [PMID: 26792038 PMCID: PMC4730940 DOI: 10.9758/cpn.2016.14.1.33] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/31/2015] [Accepted: 06/09/2015] [Indexed: 11/23/2022]
Abstract
Objective Individuals with dyslexia experience reading difficulties, whereas their other cognitive abilities seem normal. The purpose of this study was to investigate the event-related potential (ERP) patterns of children with dyslexia during a target-detection task. Methods Seventeen children with dyslexia and 18 children without this disorder participated in this study. We evaluated their writing and reading ability, symptoms of attention-deficit/hyperactivity disorder, and intelligence quotient. ERPs were recorded while participants performed a target-detection task, and the peak amplitude and latency of P100 and P300 were analyzed. The lateral asymmetry index (LAI) was calculated for each ERP component. Results The dyslexic group exhibited longer reaction times and larger P100 amplitudes than the non-dyslexic group in the right hemisphere. The P100 latency was also significantly delayed in the right hemisphere of those in the dyslexic group compared with those in the non-dyslexic group. The P300 amplitude was larger in the right hemisphere compared with left hemisphere in the dyslexic group, whereas no interhemispheric differences were observed with respect to the P300 latency. The LAI for P100 showed a significant right hemispheric dominance, whereas the LAI for P100 was significantly correlated with the accuracy of target detection in children with dyslexia. Conclusion Our results suggest that right hemispheric dominance acts as an ancillary system that compensates for poor reading in children with dyslexia.
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Affiliation(s)
- Joong-Gu Kang
- Department of Optometry, Eulji University, Daejeon, Korea.,Clinical Emotion and Cognition Research Laboratory, Goyang, Korea
| | - Seung-Hwan Lee
- Clinical Emotion and Cognition Research Laboratory, Goyang, Korea.,Department of Psychiatry, Inje University Ilsan Paik Hospital, Goyang, Korea
| | - Eun-Jin Park
- Department of Psychiatry, Inje University Ilsan Paik Hospital, Goyang, Korea
| | - Hyun-Sung Leem
- Department of Optometry, Eulji University, Daejeon, Korea
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Ullman MT, Pullman MY. A compensatory role for declarative memory in neurodevelopmental disorders. Neurosci Biobehav Rev 2015; 51:205-22. [PMID: 25597655 PMCID: PMC4359651 DOI: 10.1016/j.neubiorev.2015.01.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 12/17/2014] [Accepted: 01/08/2015] [Indexed: 11/20/2022]
Abstract
Most research on neurodevelopmental disorders has focused on their abnormalities. However, what remains intact may also be important. Increasing evidence suggests that declarative memory, a critical learning and memory system in the brain, remains largely functional in a number of neurodevelopmental disorders. Because declarative memory remains functional in these disorders, and because it can learn and retain numerous types of information, functions, and tasks, this system should be able to play compensatory roles for multiple types of impairments across the disorders. Here, we examine this hypothesis for specific language impairment, dyslexia, autism spectrum disorder, Tourette syndrome, and obsessive-compulsive disorder. We lay out specific predictions for the hypothesis and review existing behavioral, electrophysiological, and neuroimaging evidence. Overall, the evidence suggests that declarative memory indeed plays compensatory roles for a range of impairments across all five disorders. Finally, we discuss diagnostic, therapeutic and other implications.
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Affiliation(s)
- Michael T Ullman
- Brain and Language Laboratory, Department of Neuroscience, Georgetown University, Box 571464, Washington, DC 20057-1464, United States.
| | - Mariel Y Pullman
- Brain and Language Laboratory, Department of Neuroscience, Georgetown University, Box 571464, Washington, DC 20057-1464, United States
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Enhancement of brain event-related potentials to speech sounds is associated with compensated reading skills in dyslexic children with familial risk for dyslexia. Int J Psychophysiol 2014; 94:298-310. [PMID: 25312203 DOI: 10.1016/j.ijpsycho.2014.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/26/2014] [Accepted: 10/02/2014] [Indexed: 01/18/2023]
Abstract
Specific reading disability, dyslexia, is a prevalent and heritable disorder impairing reading acquisition characterized by a phonological deficit. However, the underlying mechanism of how the impaired phonological processing mediates resulting dyslexia or reading disabilities remains still unclear. Using ERPs we studied speech sound processing of 30 dyslexic children with familial risk for dyslexia, 51 typically reading children with familial risk for dyslexia, and 58 typically reading control children. We found enhanced brain responses to shortening of a phonemic length in pseudo-words (/at:a/ vs. /ata/) in dyslexic children with familial risk as compared to other groups. The enhanced brain responses were associated with better performance in behavioral phonemic length discrimination task, as well as with better reading and writing accuracy. Source analyses revealed that the brain responses of sub-group of dyslexic children with largest responses originated from a more posterior area of the right temporal cortex as compared to the responses of the other participants. This is the first electrophysiological evidence for a possible compensatory speech perception mechanism in dyslexia. The best readers within the dyslexic group have probably developed alternative strategies which employ compensatory mechanisms substituting their possible earlier deficit in phonological processing and might therefore be able to perform better in phonemic length discrimination and reading and writing accuracy tasks. However, we speculate that for reading fluency compensatory mechanisms are not that easily built and dyslexic children remain slow readers during their adult life.
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8
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Noordenbos MW, Segers E, Serniclaes W, Verhoeven L. Neural evidence of the allophonic mode of speech perception in adults with dyslexia. Clin Neurophysiol 2013; 124:1151-62. [PMID: 23403261 DOI: 10.1016/j.clinph.2012.12.044] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 12/12/2012] [Accepted: 12/22/2012] [Indexed: 11/19/2022]
Affiliation(s)
- Mark W Noordenbos
- Behavioural Science Institute, Radboud University Nijmegen, The Netherlands.
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Heim S, Wehnelt A, Grande M, Huber W, Amunts K. Effects of lexicality and word frequency on brain activation in dyslexic readers. BRAIN AND LANGUAGE 2013; 125:194-202. [PMID: 22230039 DOI: 10.1016/j.bandl.2011.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 11/18/2011] [Accepted: 12/11/2011] [Indexed: 05/12/2023]
Abstract
We investigated the neural basis of lexical access to written stimuli in adult dyslexics and normal readers via the Lexicality effect (pseudowords>words) and the Frequency effect (low>high frequent words). The participants read aloud German words (with low or high lexical frequency) or pseudowords while being scanned. In both groups, both Lexicality effect and Frequency effect involved Broca's region (areas 44 and 45). Whereas the effects were stronger for dyslexic than normal readers in area 44, area 45 showed the reverse pattern. These findings mimic recent results from an fMRI study on dyslexic primary school children, indicating that lexical access to written stimuli poses increased and enduring difficulties on dyslexic readers, at least in a language with a transparent orthography. Additionally, data from four compensated adult dyslexics are reported and discussed, which hint at the importance of both Broca's and Wernicke's region for recovery from childhood dyslexia.
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Affiliation(s)
- Stefan Heim
- Section Structural-Functional Brain Mapping, Department of Psychiatry, Psychotherapy, and Psychosomatics, Medical School, RWTH Aachen University, Germany.
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Leonard CM, Low P, Jonczak EE, Schmutz KM, Siegel LS, Beaulieu C. Brain Anatomy, Processing Speed, and Reading in School-Age Children. Dev Neuropsychol 2011; 36:828-46. [PMID: 21978008 DOI: 10.1080/87565641.2011.606398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Chiarello C, Welcome SE, Leonard CM. Individual differences in reading skill and language lateralisation: a cluster analysis. Laterality 2011; 17:225-51. [PMID: 22385144 PMCID: PMC3296279 DOI: 10.1080/1357650x.2011.561860] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Individual differences in reading and cerebral lateralisation were investigated in 200 college students who completed reading assessments and divided visual field word recognition tasks, and received a structural MRI scan. Prior studies on this data set indicated that little variance in brain-behaviour correlations could be attributed to the effects of sex and handedness variables (Chiarello, Welcome, Halderman, & Leonard, 2009; Chiarello, Welcome, Halderman, Towler, et al., 2009; Welcome et al., 2009). Here a more bottom-up approach to behavioural classification (cluster analysis) was used to explore individual differences that need not depend on a priori decisions about relevant subgroups. The cluster solution identified four subgroups of college age readers with differing reading skill and visual field lateralisation profiles. These findings generalised to measures that were not included in the cluster analysis. Poorer reading skill was associated with somewhat reduced VF asymmetry, while average readers demonstrated exaggerated RVF/left hemisphere advantages. Skilled readers had either reduced asymmetries, or asymmetries that varied by task. The clusters did not differ by sex or handedness, suggesting that there are identifiable sources of variance among individuals that are not captured by these standard participant variables. All clusters had typical leftward asymmetry of the planum temporale. However, the size of areas in the posterior corpus callosum distinguished the two subgroups with high reading skill. A total of 17 participants, identified as multivariate outliers, had unusual behavioural profiles and differed from the remainder of the sample in not having significant leftward asymmetry of the planum temporale. A less buffered type of neurodevelopment that is more open to the effects of random genetic and environmental influences may characterise such individuals.
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Affiliation(s)
- Christine Chiarello
- Department of Psychology, University of California, Riverside, Riverside, CA 92521, USA.
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Welcome SE, Chiarello C, Thompson PM, Sowell ER. Reading skill is related to individual differences in brain structure in college students. Hum Brain Mapp 2011; 32:1194-205. [PMID: 21523856 DOI: 10.1002/hbm.21101] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 04/30/2010] [Accepted: 05/05/2010] [Indexed: 11/05/2022] Open
Abstract
We compared cortical anatomy, using 3D brain MRI scans, between three groups of university students: proficient readers (skilled at phonological decoding and text comprehension), poor readers (impaired at phonological decoding and text comprehension), and resilient readers (impaired at phonological decoding but skilled in text comprehension). This latter group provides a unique opportunity to investigate associations between cortical morphology and phonological decoding deficits in individuals without attendant reading comprehension deficits. We predicted widespread reductions in gray matter thickness and brain size in temporal and frontal regions in poor readers, and more focal differences in brain morphology in resilient readers. Typical asymmetry of gray matter thickness in the temporo-parietal region was reduced in both poor and resilient readers. Poor readers also exhibited smaller brain sizes in the right inferior frontal region than both proficient and resilient readers. Altered asymmetry in the temporo-parietal region may therefore be associated with poor phonological decoding and impaired text comprehension may be associated with altered frontal morphology. Resilient readers show relatively focal behavioral differences from typical readers, so it is interesting that they show reliable differences in brain morphology.
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Affiliation(s)
- Suzanne E Welcome
- Department of Psychology, University of California-Riverside, CA, USA.
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13
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Sun YF, Lee JS, Kirby R. Brain imaging findings in dyslexia. Pediatr Neonatol 2010; 51:89-96. [PMID: 20417459 DOI: 10.1016/s1875-9572(10)60017-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 07/07/2009] [Accepted: 07/28/2009] [Indexed: 01/18/2023] Open
Abstract
Dyslexia is a brain-based disorder that has been intensively studied in the Western world for more than a century because of its social burden. However, affected individuals in Chinese communities are neither recognized nor formally diagnosed. Previous studies have concentrated on the disadvantages of reading deficits, and few have addressed non-linguistic skills, which are included in the symptoms. In addition, certain dyslexics possess visual spatial talents that have usually been ignored. In this review, we discuss the available information regarding brain imaging studies of dyslexia based on studies in Caucasian subjects. Gray matter deficits have been demonstrated in dyslexics using structural magnetic resonance imaging. Reduced neural activities in the left temporal and left parietal cortices, and diffuse widespread activation patterns in the cerebellum could be detected using functional magnetic resonance imaging. Changes in lactate levels, N-acetylaspartate/choline-containing compounds and N-acetylaspartate/creatine ratios, and phosphomonoester peak area were detected in magnetic resonance spectroscopy studies. Lower fractional anisotropy values in bilateral white matter tracts have been demonstrated by diffusion tensor imaging. Abnormal Broca's area activation was found using positron emission tomography imaging. Increased activities in the right frontal and temporal brain regions were detected using electroencephalography. Reduced hemispheric asymmetry and increased left inferior frontal activation were reported following magnetoencephalography. Although these imaging modalities are not currently diagnostic or prognostic, they are able to provide information on the causes of dyslexia beyond what was previously provided by behavioral or cognition studies.
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Affiliation(s)
- Ying-Fang Sun
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
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14
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Wiseheart R, Altmann LJP, Park H, Lombardino LJ. Sentence comprehension in young adults with developmental dyslexia. ANNALS OF DYSLEXIA 2009; 59:151-167. [PMID: 19911285 DOI: 10.1007/s11881-009-0028-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 08/17/2009] [Indexed: 05/28/2023]
Abstract
This study investigated the effects of syntactic complexity on written sentence comprehension in compensated adults with dyslexia. Because working memory (WM) plays a key role in processing complex sentences, and individuals with dyslexia often demonstrate persistent deficits in WM, we hypothesized that individuals with dyslexia would perform more poorly on tasks designed to assess the comprehension of syntactic structures that are especially taxing on WM (e.g., passives, sentences with relative clauses). Compared to their nondyslexic peers, individuals with dyslexia were significantly less accurate and marginally slower on passive sentences. For sentences containing relative clauses, the dyslexic group was also less accurate but did not differ in response times. Covarying WM and word reading in both analyses eliminated group differences showing that syntactic deficits in adults with dyslexia are constrained by both WM and word-reading ability. These findings support previous research showing that syntactic processing deficits are characteristic of dyslexia, even among high-achieving students.
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15
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Leonard CM, Towler S, Welcome S, Chiarello C. Paracingulate asymmetry in anterior and midcingulate cortex: sex differences and the effect of measurement technique. Brain Struct Funct 2009; 213:553-69. [PMID: 19636589 DOI: 10.1007/s00429-009-0210-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Accepted: 06/30/2009] [Indexed: 01/08/2023]
Abstract
Many structural brain asymmetries accompany left hemisphere language dominance. For example, the cingulate sulcus is larger in the medial cortex of the right hemisphere, while the more dorsal paracingulate sulcus is larger on the left. The functional significance of these asymmetries is unknown because fMRI studies rarely attempt to localize activation to specific sulci, possibly due to difficulties in consistent sulcal identification. In medial cortex, for example, there are many regions of partial sulcal overlap where MRI images do not provide sufficient information to unambiguously distinguish a paracingulate sulcus from a displaced anterior cingulate segment. As large samples of postmortem material are rarely available for cytoarchitectural studies of sulcal variation, we have investigated the effect of variation in boundary and sulcal definition on paracingulate asymmetry in the MRI scans of 200 healthy adults (100 men, 100 women). Although women displayed a reliable asymmetry in the size of the paracingulate sulcus, regardless of boundary definition or technique, asymmetry was greatest when (1) the measurement was limited to the midcingulate region between the genu and the anterior commissure; and (2) the more dorsal of two overlapping sulci was always classified as a paracingulate sulcus (rather than as a displaced cingulate segment). The fact that paracingulate asymmetry is maximal in the midcingulate region suggests that this region may play a particular role in hemispheric specialization for language. Future work should investigate the structural and functional correlates of sulcal variation in this region.
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Affiliation(s)
- Christiana M Leonard
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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16
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Miller JL, Couch JA, Leonard CM, Schwenk K, Towler SD, Shuster J, Goldstone AP, He G, Driscoll DJ, Liu Y. Sylvian fissure morphology in Prader-Willi syndrome and early-onset morbid obesity. Genet Med 2009; 9:536-43. [PMID: 17700392 DOI: 10.1097/gim.0b013e31812f720d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PURPOSE Prader-Willi syndrome is a well-defined genetic cause of childhood-onset obesity that can serve as a model for investigating early-onset childhood obesity. Individuals with Prader-Willi syndrome have speech and language impairments, suggesting possible involvement of the perisylvian region of the brain. Clinical observations suggest that many individuals with early-onset morbid obesity have similar speech/language deficits, indicating possible perisylvian involvement in these children as well. We hypothesized that similar perisylvian abnormalities may exist in both disorders. METHODS Participants included individuals with Prader-Willi syndrome (n = 27), their siblings (n = 16), individuals with early-onset morbid obesity (n = 13), and their siblings (n = 10). Quantitative and qualitative assessments of sylvian fissure conformation, insula closure, and planum temporale length were performed blind to hemisphere and diagnosis. RESULTS Quantitative measurements verified incomplete closure of the insula in individuals with Prader-Willi syndrome. Planar asymmetry showed its normal bias toward leftward asymmetry in all groups except those with Prader-Willi syndrome maternal uniparental disomy. Individuals with Prader-Willi syndrome and siblings had a normal distribution of sylvian fissure types in both hemispheres, while individuals with early-onset morbid obesity and their siblings had a high proportion of rare sylvian fissures in the right hemisphere. CONCLUSIONS The contrast between the anatomic findings in individuals with Prader-Willi syndrome and early-onset morbid obesity suggests that the language problems displayed by children with these two conditions may be associated with different neurodevelopmental processes.
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Affiliation(s)
- Jennifer L Miller
- Departments of Pediatrics, University of Florida, College of Medicine, Gainesville, Florida 32610-0296, USA.
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Abstract
Developmental language disorders are characterized by a maturational trajectory that deviates or lags that of normal children. Given the wide variation in the rate of normal language development, diagnosis and classification of these disorders poses severe problems for the clinician. Our laboratory has been searching for anatomical signatures that could aid the development of a neurobiologically based classification. Quantitative analysis of the magnetic resonance imaging (MRI) brain scans of a series of samples of children and adults with reading and language disorders has identified two clusters with contrasting anatomical and reading profiles. Individuals with small symmetrical brain structures tend to have deficits in multiple domains of written and oral language whereas those with larger asymmetrical structures are more likely to have the isolated phonological deficits seen in adults with compensated dyslexia. Surprisingly, the anatomical risk factors that define these clusters do not form a continuum of increasing severity but deviate in opposite directions from normal. Individuals with moderate brain size and asymmetry typically demonstrate the best overall performance. Further research should determine if phonological impairments in the two clusters are associated with differing genetic and environmental risk factors requiring different types of intervention.
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Affiliation(s)
- Christiana M Leonard
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Health Science Center, Gainesville FL 32610, USA.
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Ellis AW. Communication between the cerebral hemispheres in dyslexic and skilled adult readers. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s0214-4603(09)70146-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Dominanza emisferica. Neurologia 2009. [DOI: 10.1016/s1634-7072(09)70507-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Eckert MA, Lombardino LJ, Walczak AR, Bonihla L, Leonard CM, Binder JR. Manual and automated measures of superior temporal gyrus asymmetry: concordant structural predictors of verbal ability in children. Neuroimage 2008; 41:813-22. [PMID: 18440244 PMCID: PMC4201835 DOI: 10.1016/j.neuroimage.2008.03.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 02/28/2008] [Accepted: 03/03/2008] [Indexed: 11/19/2022] Open
Abstract
The planum temporale is a region on the posterior surface of the temporal lobe that exhibits robust leftward structural asymmetry, which has been linked to verbal ability in children and adults. Traditionally, structural asymmetry has been quantified with manual assessment of high resolution MRI scans. Such measures require subjective and frequently unreliable determination of highly variable anatomical boundaries. Methodological developments in automated image processing (voxel-based morphometry - VBM) offer the opportunity to obtain objective and reliable measures of structural variation. This study examined the extent to which a VBM measure of gray matter asymmetry in the posterior superior temporal gyrus (pSTG) characterized the same individual variation as a manual measure of planum temporale asymmetry in 99 healthy adults and 39 typically developing children. Planum temporale asymmetry was significantly correlated with pSTG gray matter asymmetry in the samples of adults and children. As a measure of validity we examined the extent to which the VBM measure of pSTG gray matter asymmetry predicted measures of verbal ability that were associated with the manual measure of planum temporale asymmetry in the same children. The two asymmetry measures predicted the same variance in verbal ability. The automated measure of pSTG gray matter asymmetry predicted additional significant variance in verbal ability, however. In addition, a posterior STS region was also identified that significantly predicted verbal ability. These results demonstrate significant advantages of an automated voxel-based measure over a manual measure of planum temporale asymmetry.
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Affiliation(s)
- Mark A Eckert
- Medical University of South Carolina, Department of Otolaryngology, Head and Neck Surgery, SC 29425, USA.
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Henderson L, Barca L, Ellis AW. Interhemispheric cooperation and non-cooperation during word recognition: evidence for callosal transfer dysfunction in dyslexic adults. BRAIN AND LANGUAGE 2007; 103:276-91. [PMID: 17544495 DOI: 10.1016/j.bandl.2007.04.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 04/25/2007] [Accepted: 04/27/2007] [Indexed: 05/15/2023]
Abstract
Participants report briefly-presented words more accurately when two copies are presented, one in the left visual field (LVF) and another in the right visual field (RVF), than when only a single copy is presented. This effect is known as the 'redundant bilateral advantage' and has been interpreted as evidence for interhemispheric cooperation. We investigated the redundant bilateral advantage in dyslexic adults and matched controls as a means of assessing communication between the hemispheres in dyslexia. Consistent with previous research, normal adult readers in Experiment 1 showed significantly higher accuracy on a word report task when identical word stimuli were presented bilaterally, compared to unilateral RVF or LVF presentation. Dyslexics, however, did not show the bilateral advantage. In Experiment 2, words were presented above fixation, below fixation or in both positions. In this experiment both dyslexics and controls benefited from the redundant presentation. Experiment 3 combined whole words in one visual field with word fragments in the other visual field (the initial and final letters separated by spaces). Controls showed a bilateral advantage but dyslexics did not. In Experiments 1 and 3, the dyslexics showed significantly lower accuracy for LVF trials than controls, but the groups did not differ for RVF trials. The findings suggest that dyslexics have a problem of interhemispheric integration and not a general problem of processing two lexical inputs simultaneously.
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Affiliation(s)
- Lisa Henderson
- Department of Psychology, University of York, York YO10 5DD, UK.
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Ecard L, Silva APSD, Peçanha Neto M, Veiga H, Cagy M, Piedade R, Ribeiro P. [The effects of functional electrical stimulation on cortical interhemispheric asymmetry]. ARQUIVOS DE NEURO-PSIQUIATRIA 2007; 65:642-6. [PMID: 17876407 DOI: 10.1590/s0004-282x2007000400019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Accepted: 04/20/2007] [Indexed: 11/21/2022]
Abstract
The aim of the present study was to assess the effects of functional electrical stimulation (FES) on cortical interhemispheric asymmetry. Electrostimulation was performed on the right forearm to stimulate the extension of the index finger. EEG activity was recorded simultaneously. The sample included 45 subjects randomly divided into 3 groups of 15 subjects each: control group (submitted to 24 blocks of stimulation at a null intensity current), group 1 (24 blocks) and group 2 (36 blocks). Interhemispheric asymmetry between F3-F4, C3-C4 and P3-P4 was analyzed through an Anova. Results pointed out to a group x electrode interaction and a general tendency of asymmetry decrease after stimulation.
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Affiliation(s)
- Letícia Ecard
- Laboratório de Mapeamento Cerebral e Integração Sensório-Motora, Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Avenida Venceslau Brás 71, Rio de Janeiro, RJ, Brazil.
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Stoodley CJ, Hill PR, Stein JF, Bishop DVM. Auditory event-related potentials differ in dyslexics even when auditory psychophysical performance is normal. Brain Res 2006; 1121:190-9. [PMID: 17010945 DOI: 10.1016/j.brainres.2006.08.095] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 08/08/2006] [Accepted: 08/26/2006] [Indexed: 11/23/2022]
Abstract
Developmental dyslexia is characterized by a phonological processing deficit and impaired low-level auditory processing may contribute to this problem. However, this remains controversial because not all dyslexic individuals show psychophysical deficits on auditory processing tasks; hence it has been argued that auditory processing deficits are not a causal factor in dyslexia. Because behavioral psychophysical tasks include both bottom-up processing and top-down strategies, dyslexics' successful coping strategies may positively influence their performance on auditory behavioral measures. Therefore we have studied whether dyslexics who perform adequately on auditory psychophysical tasks nevertheless show electrophysiological evidence of impaired auditory processing. We compared auditory event-related mismatch negativity (MMN) potentials to frequency modulated (FM) tones at 5, 20 and 240 Hz between dyslexic adults and controls. Groups were matched for age, cognitive ability and psychophysical FM detection thresholds. The dyslexic group showed significantly smaller MMNs in the 20 Hz FM condition in both the early (150-300 ms, P=0.010) and late (300-500 ms, P=0.049) time frames. A 2-way ANOVA showed a significant group by FM rate interaction (P=0.012). There were no significant differences between the groups in the 5 Hz or 240 Hz conditions. The magnitude of the 20 Hz FM MMN correlated with the degree of discrepancy between cognitive and literacy skills (0.66, P=0.003) in the entire group. Thus, even among compensated dyslexics with above-average cognitive abilities and adequate performance on auditory psychophysical tasks, the MMN responses of some dyslexic adults were found to be abnormal.
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