A study of Indian women who learnt to read in their 30s has demonstrated that the human brain can transform and reorganise itself after learning to read in adulthood.
Researchers from India, Germany and Netherlands worked with 21 Dalit women in their 30s, who could not read in their mother tongue Hindi at all. After six months of training, when they had reached the level of first-grade proficiency, they underwent brain scans in Lucknow, a three-hour drive from their homes.
"Writing is a very recent cultural invention if we look at the evolutionary history of our species..." Faulk Huettig of the Max Planck Institute for Psycholinguistics told Scientific American. "Looking at how cultural inventions change brain function and structures helps us to understand how the brain works on a fundamental level." The joint study brought together researchers from the Max Planck Institute for Psycholinguistics, Radboud University, India's Centre of Bio-Medical Research (CBMR) and the University of Hyderabad.
The results of the study left the researchers surprised. They found that the changes were not limited to the cortex or the outer part of the brain. Their new reading skills had led to a reorganisation of deep brain structures such as the brainstem and the thalamus, a structure that helps with sensory and motor functions.
"We observed that the so-called colliculi superiores, 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," co-author Michael Skeide of the Max Planck Institute for Human Cognitive and Brain Sciences told AFP. "These deep structures in the thalamus and brainstem help our visual cortex to filter important information from the flood of visual input even before we consciously perceive it."
What's more, the findings could throw new light on the cause of reading disorders such as dyslexia, which is believed to be caused by a dysfunctioning thalamus. The insight that a few months of reading training can change the thalamus might alter the treatment for dyslexia.
"The relatively young phenomenon of human literacy therefore changes brain regions that are very old in evolutionary terms and already core parts of mice and other mammalian brains," Huettig told Scientific American.