Magnocellular theory of dyslexia pathogenesis: Difficulties with motion perception or weakness of M-cells?
https://doi.org/10.26907/2541-7738.2025.4.77-86
Abstract
Dyslexia pathogenesis is generally defined based on the multifactorial nature of this disorder. One of the hypotheses is the magnocellular theory suggesting that word blindness stems from the deficit in visual gnosis, i.e., that dyslexic people have difficulties with the perception of dynamic stimuli due to the impairment of their visual M-pathway functioning. However, this point of view has been widely challenged by experts, which is probably associated with incorrect choice of diagnostic criteria. An eye-tracking study was carried out on elementary school students in order to investigate their eye movements in response to visual stimuli with varying modes of presentation. The results revealed differences between the functions of the M-pathway responsible for the holistic perception of an object and the dorsal stream processing information about the object movements. The correlations observed with the oculographic data and the reading comprehension scores confirmed that the state of visual gnosis affects the reading process. Yet, to accurately determine the contribution of the state of M-cells to the pathogenesis of dyslexia, future research should focus on stimuli defined by spatial and temporal frequencies rather than the specificity of motion alone.
About the Author
A. A. Vagapova
Kazan Federal University
Russian Federation
Russian Federation
Alsu A. Vagapova, Researcher, Neurocognitive Research Laboratory
References
1. Kornev A.N. Narusheniya chteniya i pis’ma u detei [Reading and Writing Disorders in Children]. St. Petersburg, MiM, 1997. 286 p. (In Russian)
2. Livingstone M.S., Rosen G.D., Drislane F.W., Galaburda A.M. Physiological and anatomical evidence for a magnocellular defect in developmental dyslexia. Proceedings of the National Academy of Sciences of the United States of America, 1991, vol. 88, no. 18, pp. 7943–7947. https://doi.org/10.1073/pnas.88.18.7943.
3. Richlan F., Kronbichler M., Wimmer H. Functional abnormalities in the dyslexic brain: A quantitative meta-analysis of neuroimaging studies. Human Brain Mapping, 2009, vol. 30, no. 10, pp. 3299–3308. https://doi.org/10.1002/hbm.20752.
4. Gabrieli J.D.E. Dyslexia: A new synergy between education and cognitive neuroscience. Science, 2009, vol. 325, pp. 280–283. https://doi.org/10.1126/science.1171999.
5. Grigorenko E.L. Biological nature of dyslexia: A brief review of the literature and research examples. Psychology. Journal of the Higher School of Economics, 2010, vol. 7, no. 4, pp. 20–44. (In Russian)
6. Levashov O.V. Functional asymmetry of the magno- and parvocellular (m and p) systems (phasic and tonic) associated with local brain lesions and dyslexia: A neurobiological approach. Asimmetriya, 2009, vol. 3, no. 2, pp. 73–98. (In Russian)
7. Giraldo-Chica M., Hegarty J.P., II, Schneider K.A. Morphological differences in the lateral geniculate nucleus associated with dyslexia. NeuroImage: Clinical, 2015, vol. 7, pp. 830–836. https://doi.org/10.1016/j.nicl.2015.03.011.
8. Pammer K., Wheatley C. Isolating the M(y)-cell response in dyslexia using the spatial frequency doubling illusion. Vision Research, 2001, vol. 41, no. 16, pp. 2139–2147. https://doi.org/10.1016/s0042-6989(01)00092-x.
9. Manning C., Hassall C.D., Hunt L.T., Norcia A.M., Wagenmakers E.-J., Snowling M.J., Scerif G., Evans N.J. Visual motion and decision-making in dyslexia: Reduced accumulation of sensory evidence and related neural dynamics. Journal of Neuroscience, 2022, vol. 42, no. 1, pp. 121–134. https://doi.org/10.1523/JNEUROSCI.1232-21.2021.
10. Johnston R., Pitchford N.J., Roach N.W., Ledgeway T. Visual perception in dyslexia is limited by sub-optimal scale selection. Scientific Reports, 2017, vol. 7, no. 1, art. 6593. https://doi.org/10.1038/s41598-017-06967-6.
11. Fischer B. Subitizing, dynamic vision, saccade and fixation control in dyslexia. In: Stein J., Kapoula Z. (Eds.) Visual Aspects of Dyslexia. Oxford, Oxford Univ. Press, 2012, pp. 15–44. https://doi.org/10.1093/acprof:oso/9780199589814.003.0002.
12. Gori S., Seitz A.R., Ronconi L., Franceschini S., Fаcoetti A. Multiple causal links between magnocellular–dorsal pathway deficit and developmental dyslexia. Cerebral Cortex, 2016, vol. 26, no. 11, pp. 4356 –4369. https://doi.org/10.1093/cercor/bhv206.
13. Olulade O.A., Napoliello E.M., Eden G.F. Abnormal visual motion processing is not a cause of dyslexia. Neuoron, 2013, vol. 79, no. 1, pp. 180–190. https://doi.org/10.1016/j.neuron.2013.05.002.
14. Skottun C. The need to differentiate the magnocellular system from the dorsal stream in connection with dyslexia. Brain and Cognition, 2015, vol. 95, pp. 62–66. https://doi.org/10.1016/j.bandc.2015.01.001.
15. Wright C.M., Conlon E.G. Auditory and visual processing in children with dyslexia. Developmental Neuropsychology. 2009, vol. 34, no. 3, pp. 330–355. https://doi.org/10.1080/87565640902801882.
Review
For citations:
Vagapova A.A. Magnocellular theory of dyslexia pathogenesis: Difficulties with motion perception or weakness of M-cells? Kazan Journal of Historical, Linguistic, and Legal Research. 2025;167(4):77-86. (In Russ.) https://doi.org/10.26907/2541-7738.2025.4.77-86
Views:
7
Email this article 