| Sumario: | Much evidence has now accumulated to suggest that a fundamental deficit in developmental dyslexia (in older adults) and in traumatic brain injury (TBI) is impaired operation of the visual timing functions mediated by the magnocellular system. This review summarizes these deficits and how they can be remediated rapidly by a short period of exercises aimed at improving sensitivity to moving gratings. Such movement-discrimination exercises activate both low and high levels in the visual magnocellular system, affecting both feedforward and feedback pathways. The exercises seem to boost reading by improving visual attention, memory, and executive-control networks. If the exercises precede conventional vision therapy, then all targeted cognitive skills seem to improve. The effect on reading of correcting visual timing deficits in the magnocellular pathways suggests that visual-movement discrimination plays a very important part in the acquisition of reading skills, not only in people with dyslexia, but also in typically developing children. Moreover, this research supports the hypothesis that faulty synchronization of parvocellular with magnocellular visual pathways in the dorsal stream is a fundamental cause of dyslexia and argues that the phonological reading deficiencies in dyslexia are often secondary to impaired development of the visual magnocellular timing system. Our studies call for a paradigm shift from phonologically based to visually based methods for remediating dyslexia. Such a shift is needed as well for older adults and following concussion. Importantly, this adaptive training shows cognitive transfer to tasks not trained, significantly improving a person's quality of life rapidly and effectively.
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