Defective Visual Pathway in Reading-Disabled Children

To the Editor: Lehmkuhle and coworkers (April 8 issue)¹ describe abnormalities of the visual evoked potential in children with reading disability. I disagree with the authors' interpretation of their findings as evidence of a selective abnormality of the magnicellular visual pathway. Their key observation is that transient visual evoked potentials in normal readers and subjects with reading disability are affected differently by a 12-Hz flicker in the background stimuli surrounding a target stimulus. In principle, if a 12-Hz field selectively depressed the sensitivity of magnicellular neurons, these data would suggest that a fast magnicellular pathway participated in the normal visual…