A new effective treatment for dyslexia based on dorsal visual stream neuromodulation

Abstract

Developmental dyslexia (DD) affects approximately 10% of individuals, impairing reading ability thus limiting professional fulfilment and psychological wellbeing. DD is associated with both phonological and visual deficits, and the latter are attributed to dysfunctions of the magnocellular-dorsal visual stream, which has a critical role in planning saccades and supporting the extraction of letters/words identity. Currently, there are no effective treatments to restore the brain networks underlying visuospatial analysis and oculomotor efficiency. Adults with DD were enrolled in a randomised clinical trial introducing a non-invasive neuromodulation protocol specifically designed to enhance dorsal stream functionality. We used bi-focal beta-band transcranial alternating current stimulation (tACS) in parietal areas, due to the recognized role of beta oscillation in the dorsal stream functionality. Coupled with a 12-session visuoattentional training, such protocol induced improvements in reading speed, oculomotor control, and visual motion perception. Additionally, beta-tACS led to long-term enhancement of working memory. These outcomes were exclusive or superior to those obtained with a placebo/sham neuromodulation, and were accompanied by plastic changes in the stimulated brain networks. Overall, our findings show the efficacy of multisession tACS in improving core visual, oculomotor and cognitive deficits associated with reading disorders.