Learning to Read Can Dramatically Change the Adult Brain

Scientists have long known that learning shapes the brain. Speaking multiple languages, accruing new skills or even just quitting a habit can forge new neural pathways. But a new study has brought a surprising twist to our understanding of how the brain molds itself to new abilities—in particular, learning to read as an adult. Literacy, it turns out, changes ancient regions of the brain that researchers never suspected played a role in reading. The finding expands not only our understanding of reading but also disorders that impair it, namely dyslexia.

Neurologists and psychologists from several institutions worldwide recruited 30 illiterate people, mostly women around age 30, from two villages near the northern India city of Lucknow, to their study. Over six months, a local school teacher taught the participants to read Devanagari, the alphabet used for many languages including their native Hindi. The researchers took MRI images of all the participants' brains before the instruction began and at the end of the six months.

The villagers learned to read and write the 46 characters used in Devanagari during the first month and soon became adept with two-syllable words. By the end of the study, the participants could read complex words, knew basic grammar rules and understood tense and gender rules. Their literacy was tested at the beginning and end of the study, with a total of 21 participants completing the full study, which has just been published in Science Advances.

The images taken at the start and end of the six months showed stark differences in what neurologists refer to as the subcortical structures of the brain. These structures are located between the retina, where light enters our eyes, and the visual cortex, where our brains begin consciously perceiving visual information.

The dramatic reshaping of the subcortical structures as the adults learned to read was surprising. Reading is a relatively recent skill, explains lead study author Michael Skeide, a neuropsychologist at the Max Planck Institute for Human Cognitive and Brain Sciences in Germany, but the subcortical structures are, "very old in evolutionary terms." In other words, we don't expect brain structures like these, which are present in species that have been on Earth for far longer than humans, to respond to a uniquely human and recently acquired skill.

This region is not the one expected to change with reading acquisition, says Laurent Cohen, who teaches neurology at University Hospital of the Salpêtrière, in Paris, and who was not involved with the study. The role of this region in literacy was previously unknown, says Cohen, and the data clearly show that with literacy, "those structures get more connected to the rest of the brain."

Even though the change was surprising, Skeide says it makes sense. "In order to become a proficient reader, you need visual navigation skills," he says. For millions of years, humans have learned to recognize trees, rocks and other features as part of our survival. "Written stimuli are a new set of features," says Skeide, "and our visual system has to adapt."

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Skeide also highlights the implications for understanding dyslexia. Scientists have proposed dozens of different theories to explain the causes of dyslexia, a general term for disorders that impair reading skills. One of those theories says that dyslexia is caused by those very subcortical structures that were transformed in the villagers in the study. Previous studies indicated differences in those regions between adults with and without dyslexia.

Although it's tempting to think that this new study proves that theory, in fact, says Skeide, it does the opposite. The transformation of the subcortical structure during the six-month literacy program indicates that this region does not cause dyslexia. Rather, says Skeide, the difference observed in other studies, "might just reflect the simple fact that dyslexic individuals spend less time reading." Because the dyslexia impedes reading, individuals with this condition spend less time doing it, which in turn leaves the subcortical structures underdeveloped.

In addition to the neurological discovery, the study also transformed the lives of its participants. "Being educated to read and spell is really a privilege in Indian society," says Skeide. "We changed their life profoundly and opened up a new world for them."

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