Neuroscience and Learning

Neuroscience and Learning to Read

Learning to read is a process that requires the learner to acquire a number of complex skills, including morphology (formation of words), orthography (spelling), phonetics (mapping words to sounds), syntax (word order), and semantics (extraction of meaning from words and sentences). Fluent readers have automated these skills to the extent that the entire process from seeing to understanding occurs very rapidly—within about 600 milliseconds.

Though certain brain structures are biologically primed for language (e.g., Broca’s area and Wernicke’s area), language acquisition requires experience. Language circuits are known to be most receptive to experience-dependent changes at certain stages of the individual’s development. For example, sound discrimination is best developed in the first 10 months of age and accents are acquired most effectively before 12 years of age. If the initial exposure to a foreign language occurs between 1 and 3 years of age, grammar is processed by the left hemisphere, but when second language exposure occurs later, there is typically an aberrant activation pattern consistent with significant difficulties with second-language grammar.

Reading of alphabetic scripts is also lateralized to the left hemisphere. The occipital-temporal areas of the brain are most active when processing letter shapes and orthography. Activation in these areas increases with reading skills and is diminished in children with developmental dyslexia.

One of the major debates in literacy education and research has been whether the whole language text immersion approach is more effective than is the development of phonetic skills. Neuroscience research aimed at delineating the brain areas that support reading provides useful insights regarding this issue. The so-called dual-route theory provides a framework for describing reading in the brain at the level of the word. Supported by dozens of neuroimaging studies, this theory proposes that words are first processed by the primary visual cortex and then pre-lexical processing occurs at the left occipito-temporal junction. After that, processing follows one of two complementary pathways. The assembled pathway involves an intermediate step of converting letters and words into sounds, which occurs in certain left temporal and frontal areas, including Broca’s area. The discovery of this pathway suggests the importance of the phonic approach to reading instruction. In case of the second route, the addressed pathway, information is transferred directly from pre-lexical processing to semantic processing (meaning extraction), which implies the significance of using the whole language approach to teach reading. Both pathways terminate in Wernicke’s area, which is known to be involved in the understanding of written and spoken language. These results confirm the assumptions of the dual-route framework, which helps explain different patterns of activation observed in participants during a reading task. This neuroscience finding is also consistent with the conclusions of the 2000 U.S. National Reading Panel that highlight the educational benefits of a balanced approach to reading instruction, which combines whole language and phonics approaches.

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