Dyslexies-dysorthographies

Bellocchi, S., Muneaux, M., Bastien-Toniazzo, M., & Ducrot, S. (2013). I can read it in your eyes: What eye movements tell us about visuo-attentional processes in developmental dyslexia. Research in developmental disabilities34(1), 452-460.

Most studies today agree about the link between visual-attention and oculomotor control during reading: attention seems to affect saccadic programming, that is, the position where the eyes land in a word. Moreover, recent studies show that visuo-attentional processes are strictly linked to normal and impaired reading. In particular, a large body of research has found evidence of defective visuo-attentional processes in dyslexics. What do eye movements tell us about visuo-attentional deficits in developmental dyslexia? The purpose of this paper is to explore the link between oculomotor control and dyslexia, taking into account its heterogeneous manifestation and comorbidity. Clinical perspectives in the use of the eye-movements approach to better explore and understand reading impairments are discussed.

Franceschini, S., Gori, S., Ruffino, M., Pedrolli, K., & Facoetti, A. (2012). A causal link between visual spatial attention and reading acquisition. Current Biology22(9), 814-819.

Romani, C., Tsouknida, E., & Olson, A. (2015). Encoding order and developmental dyslexia: A family of skills predicting different orthographic components. The Quarterly Journal of Experimental Psychology68(1), 99-128.

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.

Tordjman, S., Vaivre-Douret, L., Chokron, S., & Kermarrec, S. (2018). Les enfants à haut potentiel en difficulté: apports de la recherche clinique. L’Encéphale44(5), 446-456. 

Ullman, M. T. (2004). Contributions of memory circuits to language: The declarative/procedural model. Cognition92(1-2), 231-270.

The structure of the brain and the nature of evolution suggest that, despite its uniqueness, language likely depends on brain systems that also subserve other functions. The declarative/procedural (DP) model claims that the mental lexicon of memorized word-specific knowledge depends on the largely temporal-lobe substrates of declarative memory, which underlies the storage and use of knowledge of facts and events. The mental grammar, which subserves the rule-governed combination of lexical items into complex representations, depends on a distinct neural system. This system, which is composed of a network of specific frontal, basal-ganglia, parietal and cerebellar structures, underlies procedural memory, which supports the learning and execution of motor and cognitive skills, especially those involving sequences. The functions of the two brain systems, together with their anatomical, physiological and biochemical substrates, lead to specific claims and predictions regarding their roles in language. These predictions are compared with those of other neurocognitive models of language. Empirical evidence is presented from neuroimaging studies of normal language processing, and from developmental and adult-onset disorders. It is argued that this evidence supports the DP model. It is additionally proposed that “language” disorders, such as specific language impairment and non-fluent and fluent aphasia, may be profitably viewed as impairments primarily affecting one or the other brain system. Overall, the data suggest a new neurocognitive framework for the study of lexicon and grammar.

Van der Mark, S., Bucher, K., Maurer, U., Schulz, E., Brem, S., Buckelmüller, J., … & Brandeis, D. (2009). Children with dyslexia lack multiple specializations along the visual word-form (VWF) system. Neuroimage47(4), 1940-1949.

Developmental dyslexia has been associated with a dysfunction of a brain region in the left inferior occipitotemporal cortex, called the “visual word-form area” (VWFA). In adult normal readers, the VWFA is specialized for print processing and sensitive to the orthographic familiarity of letter strings. However, it is still unclear whether these two levels of occipitotemporal specialization are affected in developmental dyslexia.Specifically, we investigated whether (a) these two levels of specialization are impaired in dyslexic children with only a few years of reading experience and (b) whether this impairment is confined to the left inferior occipitotemporal VWFA, or extends to adjacent regions of the “VWF-system” with its posterior–anterior gradient of print specialization. Using fMRI, we measured brain activity in 18 dyslexic and 24 age-matched control children (age 9.7–12.5 years) while they indicated if visual stimuli (real words, pseudohomophones, pseudowords and false-fonts) sounded like a real word. Five adjacent regions of interest (ROIs) in the bilateral occipitotemporal cortex covered the full anterior–posterior extent of the VWF-system. We found that control and dyslexic children activated the same main areas within the reading network. However, a gradient of print specificity (higher anterior activity to letter strings but higher posterior activity to false-fonts) as well as a constant sensitivity to orthographic familiarity (higher activity for unfamiliar than familiar word-forms) along the VWF-system could only be detected in controls. In conclusion, analyzing responses and specialization profiles along the left VWF-system reveals that children with dyslexia show impaired specialization for both print and orthography.

Weiss, A. H., Granot, R. Y., & Ahissar, M. (2014). The enigma of dyslexic musicians. Neuropsychologia54, 28-40.

Musicians are known to have exceptional sensitivity to sounds, whereas poor phonological representations (or access to these representations) are considered a main characteristic of dyslexic individuals. Though these twocharacteristics referto different abilities that arerelated tonon-verbal and verbal skills respectively, the recent literature suggests that they are tightly related. However, there are informal reports of dyslexic musicians. To better understand this enigma, two groups of musicians were recruited, with and without a history of reading difficulties. The pattern of reading difficulties found among musicians was similar to that reported for non-musician dyslexics, though its magnitude was less severe. In contrast to non-musician dyslexics, their performance in pitch and interval discrimination, synchronous tapping and speech perception tasks, did not differ from the performance of their musician peers, and was superior to that of the general population. However, the auditory working memory scores of dyslexic musicians were consistently poor, including memory for rhythm, melody and speech sounds. Moreover, these abilities were inter-correlated, and highly correlated with their reading accuracy. These results point to a discrepancy between their perceptual and working memory skills rather than between sensitivity to speech and non-speech sounds. The results further suggest that in spite of intensive musical training, auditory working memory remains a bottleneck to the reading accuracy of dyslexic musicians.

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