A new study has found that deep areas of the brain are re-purposed to create the neural network necessary for acquiring literacy skills. Luckily, even the adult brain can undergo this process with relative ease.
Writing and, by extension, reading are relatively new skills for humans. Expressing language through a series of written marks evolved independently in multiple locations but two of the earliest known examples are cuneiform writing in Mesopotamia and hieroglyphics in Ancient Egypt, which both date back to around 3500 BC to 3000 BC.
Scientists have not found specific genes for reading. It is believed that, when learning to read, the brain needs to repurpose areas involved in visual recognition to act as an interface for reading and understanding written language. It was assumed that most of these changes are limited to the cortex, the outer layer of the brain. However, new evidence suggests that this is not the case.
A study published in Science Advances on May 24, 2017 details the results of research investigating changes that occur in the brain when completely illiterate adults learn to read and write. This research was an interdisciplinary collaboration between the Max Planck Institute for Psycholinguistics and Human Cognition and Brian Science in Germany, Radboud University in the Netherlands, and the Universities of Hyderabad and Allahabad in India.
According to the study, in India, where poverty and gender affect access to education, the illiteracy rate is approximately 39%. 21 volunteers of the same social class from two villages in Northern India were recruited into the study. Nearly all were women in their thirties and many were not able to decode a single word written in Hindi, their native language. Over the course of 6 months, participants were given reading lessons. In addition, each participant was driven by taxi to the city of Lucknow (3 hours away) so that brain scans (functional magnetic resonance imaging, or MRIs) could be performed both at the beginning and end of the 6-month period.
Remarkably, most participants learned to read Hindi at the equivalent of a first-grade level. The researchers also observed that the learning process appeared to lead to neural changes which extended to deep structures in the thalamus and the brainstem. Lead researcher, Michael Skeide stated, “we observed that the so-called colliculi superiors, a part of the brainstem, and the pulvinar, located in the thalamus, adapt the timing of their activity patterns to those of the visual cortex” which helps us filter visual stimuli before we even perceive it. In addition, they found that when the signal timing between these two regions of the brain were aligned, reading proficiency was higher. They concluded that, “the relatively young phenomenon of human literacy therefore changes brain regions that are very old in evolutionary terms.”
By indicating that the adult brain is still flexible enough to enable individuals to acquire literacy skills, this study provides hope for illiterate adults who may feel that it is too late for them to learn. Moreover, if just a few months of literacy education can lead to fundamental changes in the thalamus, then the hypothesis that dyslexia may be caused by thalamus dysfunctions will need further study. One possible way of investigating this would be to check for thalamus dysfunction in preschool children (who have not yet begun to read) from families with a history of dyslexia.
Written By: Debra A. Kellen, PhD