Reading is not a natural human ability. According to Dr. Sally Shaywitz, “reading is an acquired act, an invention of man that must be learned at a conscious level.” Reading was invented by humans over 5,000 years ago. It is not innate like learning to speak. Our brains have a genetically predetermined phonological module that puts phonemes into words for those speaking and breaks apart the word into phonemes for the listener. Readers, on the other hand, must understand phonemes in speech, apply them to letter patterns and understand what these symbols stand for in their writing system.
Speech is evolutionary, reading skills are acquired. These evolutionary neural systems that support visual processing as well as language must reorganize when reading. Only a portion of our visual cortex has the specific combination of resolution, shape specialization and connectivity needed for proficient reading. Reading must be explicitly taught.
Reading does not just occur in one area of the brain, but rather in regions from all four lobes. Three of these regions are used for decoding: the left occipitotemporal region, the left temporoparietal cortex, and the left inferior frontal gyrus in the frontal lobe. Functional magnetic resonance imaging (fMRI) studies in those who were proficient readers have shown that these regions of the brain are more active than other parts during reading. In contrast, those with dyslexia show less of an increase in the occipitotemporal cortex, inferior frontal gyrus, and left temporoparietal cortex while reading.
When children understand the alphabetic principle, a lexical system develops in the brain’s left occipitotemporal ventral system; this system operates with the dorsal system as an orthographic processor. For most dyslexic children, this dorsal system is the source of difficulty. When reading, those with dyslexia activate different brain regions and use different pathways than typical readers. Good readers activate this back area of the brain while reading, but dyslexic readers have an underactivation of neural pathways in this part of the brain. People with dyslexia actually have an overactivation in the frontal Broca’s region to compensate for this disruption in the back of the brain.
Reading is a complex process that involves multiple brain regions. Reading is an acquired skill that must be explicitly taught. However, for people with dyslexia, reading can be a challenge due to differences in the way their brains process language. Children must receive instruction and exposure to learn how to read. Once people have oral language skills, they must then learn how letters have corresponding sounds and learn phonics skills to decode these words. Early intervention and instruction can help people with dyslexia learn to read and write successfully.
Sources:
Dehaene, S. (2011). Reading as neuronal recycling: A universal brain organization underlying reading acquisition. In P. McCardle, B. Miller, J. R. Lee, & O. J. L. Tzeng (Eds.), Dyslexia across languages: Orthography and the brain–gene–behavior link. (pp. 102–116). Paul H Brookes Publishing.
Kearns, D. M., Hancock, R., Hoeft, F., Pugh, K. R., & Frost, S. J. (2019). The neurobiology of dyslexia. Teaching Exceptional Children, 51(3), 175–188.
Martin, A., Kronbichler, M., & Richlan, F. (2016). Dyslexic brain activation abnormalities in deep and shallow orthographies: A meta‐analysis of 28 functional neuroimaging studies. Human Brain Mapping, 37(7), 2676–2699.
Miciak, J., & Fletcher, J. M. (2020). The critical role of instructional response for identifying dyslexia and other learning disabilities. Journal of Learning Disabilities, 53(5), 343–353.
Ordetx, K. (2020). What Is Balanced Literacy? Part 2 of Structured Literacy vs. Balanced Literacy. IMSE - Journal.
Shaywitz, S. E. (2020). Overcoming dyslexia : a new and complete science-based program for reading problems at any level. A.A. Knopf.
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