Deficits in the magnocellular pathway of people with reading difficulties

Abstract

Purpose of Review: The magnocellular theory is one of the well-accepted neurobiological theories to explain developmental dyslexia. However, criticism remains on whether the weaker magnocellular-dorsal system in dyslexics is a consequence of insufficient practice in reading skills. This mini-review summarizes recent publications investigating the causal relationship of magnocellular theory in developmental dyslexia. Recent Findings: Emerging evidence highlights visual magnocellular-dorsal deficits as a cause, not a consequence, of reading difficulties. Recent studies have indicated that cognitive impairment of magnocellular-dorsal functions is a biomarker of developmental dyslexia and does not relate to the reading experience. However, training magnocellular-dorsal functions can also improve the reading skills in dyslexic children. Summary: Magnocellular-dorsal functions should be included in the battery of tests to identify children at risk of developmental dyslexia. However, other factors discussed in this review, including the involvement of the parvocellular system and noise cancellation deficit, should also be considered.