Visual Dyslexia

Abstract Purpose To revive the idea which was previously generally accepted, that learning to sequence written text visually is the crucial first step in learning to read. But in the last few years the phonological theory of dyslexia (PT) has become dominant. It asserts that DD is due to a psycho-linguistic deficit causing difficulty with grasping the concept of phonemes. This ignores a century of research showing that the development of a network of visual magnocellular neurons (M- cells) that signal the timing of visual events precedes and is essential for the development of phonological awareness. Recent Findings We review the cerebral structures with which the visual M- system is associated in reading alphabetic and other scripts and show in each case how their development is impaired in DD. The simplest way to improve M- cell function involves viewing text through yellow or blue filters; we discuss how these may work. Even simpler is improving children’s nutrition; and we discuss some aspects of this. The genes which are associated with the M- system also play an important role in regulating the immune system; hence we discuss how DD is associated with autoimmune conditions such as asthma and eczema and disordered control of inflammation. Summary There is now a very great weight of evidence demonstrating that visual sequencing of text mediated by the visual magnocellular timing system is the first essential for learning to read, and that impaired development of this system is a major cause of Developmental Dyslexia.