Dyslexia is a frequent disorder of reading acquisition that affects up to 10% of the population, and is characterized by lifelong difficulties with written material. Although several possible causes have been proposed for dyslexia, the predominant one is a phonological deficit, a difficulty in processing language sounds. The phonological deficit in dyslexia is associated with changes in rhythmic or repetitive patterns of neural activity in a sound-processing region of the brain, the left auditory cortex. Neuroscientists from the University of Geneva (UNIGE) have demonstrated, in a study published on line on September 8, 2020 in Plos Biology, a causal relationship between brain oscillations at a specific frequency (30 Hz) and the ability to process phonemes that is essential for reading. Using a non-invasive electrical stimulation technique capable of synchronizing neural activity at the stimulation frequency, phonological deficits and reading accuracy could be improved in adults with dyslexia. Silvia Marchesotti, PhD, and Anne-Lise Giraud, PhD, respectively researcher and professor in the Department of Basic Neurosciences of the Faculty of Medicine at UNIGE, together with their colleagues, investigated the main possible cause of dyslexia: the phonological deficit. The article is titled “Selective Enhancement of Low-Gamma Activity by tACS Improves Phonemic Processing and Reading Accuracy in Dyslexia.” "We know that during brain development, when children start to read, some experience tremendous difficulties matching speech sounds with letters," explains Dr. Marchesotti. These specific difficulties are associated with anomalies of neural activity synchronization in the left auditory cortex at the frequency of 30 Hz.
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