Children with Dyslexia Have Altered Cross-Modal Processing Linked to Binocular Fusion. A Pilot Study

Abstract

Patrick Quercia, 1 Thierry Pozzo, 2 Alfredo Marino, 3 Anne Laure Guillemant, 1 Céline Cappe, 4 Nicolas Gueugneau 1 1Université de Bourgogne, Dijon, Campus Universitaire, UFR STAPS, BP 27877, F-21078 Dijon, France; INSERM U1093, Cognition, Action et Plasticité Sensorimotrice, Dijon F-21078, France; 2Center for Translational Neurophysiology, Istituto Italiano di Tecnologia, Ferrara, Italy; 3Private Consultant, Vicenza 36100, Italie; 4Brain and Cognition Research Center, CerCo, CNRS UMR 5549, Toulouse, FranceCorrespondence: Patrick QuerciaMedical Office, 15 Rue du Clair Matin, Beaune 21200, FranceTel [phone]Email [email protected]: The cause of dyslexia, a reading disability characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities, is unknown. A considerable body of evidence shows that dyslexics have phonological disorders. Other studies support a theory of altered cross-modal processing with the existence of a pan-sensory temporal processing deficit associated with dyslexia. Learning to read ultimately relies on the formation of automatic multisensory representations of sounds and their written representation while eyes fix a word or move along a text. We therefore studied the effect of brief sounds on vision with a modification of binocular fusion at the same time (using the Maddox Rod test).Methods: To check if the effect of sound on vision is specific, we first tested with sounds and then replaced them with proprioceptive stimulation on 8 muscular sites. We tested two groups of children composed respectively of 14 dyslexic children and 10 controls.Results: The results show transient visual scotoma (VS) produced by sensory stimulations associated with the manipulation of oculomotor balance, the effect being drastically higher in the dyslexic group. The spatial distribution of the VS is stochastic. The effect is not specific for sounds but exists also with proprioceptive stimulations.Discussion: Although there was a very significant difference between the two groups, we were not able to correlate the (VS) occurrence with the dyslexic’s reading performance. One possibility to confirm the link between VS and reading impairment would be to find a specific treatment reducing the occurrence of the VS and to check its effect on dyslexia.Keywords: multisensory integration, developmental dyslexia, ocular proprioception, auditory, visual, proprioception, binocular balance

Keywords

• multisensory integration
• developmental dyslexia
• ocular proprioception
• auditory
• visual
• proprioception
• binocular balance;