Learning to read changes the adult brain

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Reading is an activity that does not come to us naturally, but with gradual learning can have a profound impact on our brains. In her book “Proust and the Squid”, Maryanne Wolf describes the long process of reading acquisition by ancient civilisations – from simple writing systems and tokens to creation of alphabets that provided improved mechanisms of encoding information. When a child learns to read, it is equally laborious. Don’t be fooled by the seeming lack of effort with which you may enjoy reading now – the basis for successful reading acquisition is formed in infancy, during which the presence of adults talking and reading can strongly influence the proficiency of readers in adulthood.

When acquired in childhood, the skill of reading helps shape the rapidly growing brain. But what about when reading is acquired as a new skill in adults? We are aware of the brain’s remarkable ability to reorganise itself in response to stimuli, but to what extent can an already mature brain remodel itself? To find out, an international team of scientists from India, Germany and the Netherlands selected two groups of people from two villages in North India. A cohort of mostly females in their 20s and 30s, the subjects spoke Hindi but could neither read nor write. Their socioeconomic backgrounds were matched: all participants had comparable monthly income and similar numbers of literate family members.

For six months, the participants learned to read Devanagari script – not a trivial task, especially considering there are 47 primary characters! Moreover, Devanagari is not simply an alphabet: it also has characteristics of a logographic writing system, such as Japanese or Chinese, where the symbols do not simply correspond to individual sounds but are more visually complex and convey larger language units. By the end of the six months, the subjects’ newly acquired ability to read was tested. The trained group showed a significant improvement, whereas the untrained group showed no difference in their reading abilities. The effects of reading acquisition on the brain during these months were studied by functional magnetic resonance imaging (fMRI), which allowed the scientists to monitor changes in the haemodynamic activity – or the patterns of blood flow in the brain. Upon reading acquisition, certain areas of the brain started working harder and required a greater blood supply, which could be measured using the fMRI.

As expected, letter identification and word-reading skill acquisition was associated with new connections in the brain. The current model of reading postulates that the primary area affected by reading is the occipital lobe – the part of the brain cortex responsible for visual processing. However, the most striking conclusion of the study is that the changes occurred not only in the occipital lobe, but also the subcortical areas – in the midbrain, responsible for visual processing, and the thalamus, the brain’s centre responsible for general information processing. These regions also include the areas in charge of eye movement and visuospatial perception (our ability to orient ourselves in a surrounding environment). Following literacy acquisition, the occipital lobe and the subcortical regions showed increased connectivity, which demonstrates the profound effect that reading has on the human brain. The findings of the study may shed new light on understanding of developmental dyslexia, in which the thalamus is one of the most affected areas.  

The authors of the study admit its limitations: the sample size of the study is quite small, with around 20 people in the trained group and only nine in the untrained. Moreover, the observed changes in the brain may not be directly associated with reading but rather with the skill of recognising intricate symbols. The time-scale is also limited: it would be interesting to see how the brain responds to reading in the long-term. Nevertheless, the study demonstrates that literacy acquisition has profound effects, not only on a developing child brain, but also on fully formed adult brain, highlighting the scale of the brain’s plasticity even in adulthood.    

 

This article was written by Alina Gukova and edited by Bonnie Nicholson.

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