The concept of a magnocellular deficit in reading difficulties has gained great traction over the past decade or two, particularly in Europe and Australia. A couple of years ago we shared an excellent review of a book on the Visual Aspects of Dyslexia that reviewed this research in great detail.
Recently I came across an outstanding powerpoint by Stuart Warren, an optometrist from New Zealand, summarizing the role of a magnocellular or M-pathway deficit in The Visual Model of Reading. Here a few key slides:
It is Warren’s last point about a standardized battery of tests targeting M-Pathway functions essential for learning that I wish to explore in more detail. A good start on this was made last year by Dr. Barry Tannen and his colleagues in their published research on the correlation of magnocellular function with measurement of reading in children. One of the key probes in that study isolating the M-Pathway is coherent motion, for which there isn’t yet a commercially available diagnostic tool. The detection of dots moving in the same direction among randomly moving dots looks like this:
Another of the Tannen Group’s key probes in the study is CFF (Critical Flicker Fusion), which is now commercially available through Bernell.
Another pertinent study and related assessment tool was authored by Teri Lawton, Ph.D., titled Improving Magnocellular Function in the Dorsal Stream Remediates Reading Deficits. Dr. Lawton’s research culminated in training software that is part of her Path to Reading Program.