FREE NEJM E-TOC    HOME   |   SUBSCRIBE   |   CURRENT ISSUE   |   PAST ISSUES   |   COLLECTIONS   |   Search Term  Advanced Search

Sign in | Get NEJM's E-Mail Table of Contents — Free | Subscribe

Previous Volume 328:989-996 April 8, 1993 Number 14 Next

	Full Text Letters Add to Personal Archive Add to Citation Manager Notify a Friend E-mail When Cited PubMed Citation

ABSTRACT

Background The possibility that reading disability in children is associated with visual problems is in dispute. We sought to test the existence of this association by using electrophysiologic techniques to measure the processing of visual information in the magnicellular and parvicellular visual pathways of the brain.

Methods Visual evoked potentials were measured with scalp electrodes in children 8 to 11 years old who were normal readers and in those with reading disability. The potentials were measured for targets with low (0.5 cycle per degree of visual angle) and high (4.5 cycles per degree) spatial frequency, surrounded by either a steady background or a uniform-field flickering 12 times per second. A flickering field normally reduces the amplitude and increases the latency of a transient potential evoked by a low-spatial-frequency target, which preferentially excites the magnicellular visual pathway, but has little effect on the response to a high-spatial-frequency target.

Results With a steady background, the latencies of the early components (N1 and P1) of the visual evoked potentials were longer in the reading-disabled children than in the normal readers when the low-spatial-frequency target was used, but not when the high-spatial-frequency target was used. In normal readers, the flickering background increased the latency and reduced the amplitude of the early components, whereas in the reading-disabled children only the amplitude was affected. No differences were observed in either group with the high-spatial-frequency target.

Conclusions The pattern of results suggests that the response of the magnicellular visual pathway is slowed in reading-disabled children, who do not, however, have a general slowing of the visual response. The possibility that there is a cause-and-effect relation between these findings and reading disability will require further study.

Source Information

From the School of Optometry, University of Missouri-St. Louis, 8001 Natural Bridge Rd., St. Louis, MO 63121, where reprint requests should be addressed to Dr. Lehmkuhle.

Full Text of this Article

Related Letters:

Defective Visual Pathway in Reading-Disabled Children
Victor J. D., Lehmkuhle S., Garzia R. P.
Extract | Full Text  
N Engl J Med 1993; 329:579, Aug 19, 1993. Correspondence

This article has been cited by other articles:

• Birch, S., Chase, C. (2004). Visual and Language Processing Deficits in Compensated and Uncompensated College Students with Dyslexia. J Learn Disabil 37: 389-410 [Abstract]  
• Fitch, R. H., Tallal, P. (2003). Neural Mechanisms of Language-Based Learning Impairments: Insights from Human Populations and Animal Models. Behav Cogn Neurosci Rev 2: 155-178 [Abstract]  
• Watson, C. S., Kidd, G. R., Horner, D. G., Connell, P. J., Lowther, A., Eddins, D. A., Krueger, G., Goss, D. A., Rainey, B. B., Gospel, M. D., Watson, B. U. (2003). Sensory, Cognitive, and Linguistic Factors in the Early Academic Performance of Elementary School Children: The Benton-IU Project. J Learn Disabil 36: 165-197 [Abstract]  
• Ben-Yehudah, G., Sackett, E., Malchi-Ginzberg, L., Ahissar, M. (2001). Impaired temporal contrast sensitivity in dyslexics is specific to retain-and-compare paradigms. Brain 124: 1381-1395 [Abstract] [Full Text]  
• Solan, H. A., Larson, S., Shelley-Tremblay, J., Ficarra, A., Silverman, M. (2001). Role of Visual Attention in Cognitive Control of Oculomotor Readiness in Students with Reading Disabilities. J Learn Disabil 34: 107-118 [Abstract]  
• Brunswick, N., McCrory, E., Price, C. J., Frith, C. D., Frith, U. (1999). Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz?. Brain 122: 1901-1917 [Abstract] [Full Text]  
• PERRY, C. A., RICE, R. E. (1999). Network Influences on Involvement in the Hybrid Problem Area of Developmental Dyslexia. Science Communication 21: 38-74 [Abstract]  
• Eden, G., Zeffiro, T. (1999). Letters. J Learn Disabil 32: 378-378  
• Solan, H. A. (1999). Letters. J Learn Disabil 32: 282-283  
• Demb, J. B., Boynton, G. M., Heeger, D. J. (1998). Functional Magnetic Resonance Imaging of Early Visual Pathways in Dyslexia. J. Neurosci. 18: 6939-6951 [Abstract] [Full Text]  
• Demb, J. B., Boynton, G. M., Heeger, D. J. (1997). Brain activity in visual cortex predicts individual differences in reading performance. Proc. Natl. Acad. Sci. USA 94: 13363-13366 [Abstract] [Full Text]  
• Victor, J. D., Lehmkuhle, S., Garzia, R. P. (1993). Defective Visual Pathway in Reading-Disabled Children. NEJM 329: 579-579 [Full Text]