Learning to read is hard when you are a kid, and even harder as an adult. New research published Wednesday in Science Advances has revealed what your brain is doing when you learn to read as an adult, and found that brain regions associated with ancient functions are largely responsible for our ability to read.
Why study the brain while someone is learning to read?
Reading is a relatively new accomplishment in terms of human history. It is not associated with any particular gene but instead is an ability to recognize complex shapes for other reasons of survival — knowing the shape of an animal that wants to kill you versus one that doesn't is a useful ability — and that ability has been co-opted by the phenomenon of reading.
So, understanding how the brain learns to read, and which brain regions are recruited to achieve this abstract skill, can help researchers understand how complexity is learned.
How do you study the brain while it is learning to read?
A lot of research has gone into studying a child's brain during learning, but there's just so much happening in their brain that it is hard to tease apart and isolate all the different stimuli and the learning that's happening. The adult brain is thought to be less plastic, or less able to adapt and change than the child's brain, so researchers studied adults learning to read.
They took 21 women in their 30s from India, where the literacy rate among women is only about 63 per cent. They did six months of reading training and raised the women's literacy up to the level of a first grader. The women were taught to read Devanagari which is a system of writing common in India. It's very cursive and has both alphabetical sounds as well as symbolic sounds. This made it really interesting to study because it has features of two different styles of writing and reading.
While all this was happening, the women were getting blood oxygen level dependent brain scans — BOLD for short — where they use a functional magnetic resonance imager (or fMRI) to watch where the oxygen was going in their brains. This demonstrated what parts of the brain were activated when learning.
What parts of the brain are needed to read?
This was a bit surprising. The cerebral cortex — that's the part of the brain associated with learning and higher intellectual processes — was involved, but the researchers had expected that. What they didn't expect was how profound an effect learning to read had on other areas of the brain.
The ability to read stimulated deeper, more ancient brain structures like the thalamus that normally functions as a relay point to integrate sensory and motor input and is involved in consciousness and sleep regulation. None of those functions you'd really associate with reading.
There are also other brain structures that are part of a very ancient system of processing visual input that we would share with mice and other mammals. These included the right superior colliculus that is involved in fine-tuning the movement of the eye, which makes sense because when you are scanning or reading, you need fine-tune and focus on the words and finer points of the letters.
What they found was that the ability to read is not unique to humans in that other mammals can distinguish complex written shapes, and we share those brain regions. This doesn't mean mice can read Tolstoy, but that they have similar brain structures to process complex symbols. What they can't do, and what we can, is ascribe meaning to those shapes. We use our higher level processing centres in our cortex to do this.
Ultimately, they found profound changes in how the brain's connections are made once you learn how to read, and some of those connections are in very ancient brain systems.
Can studies like these help understand reading disorders like dyslexia?
They can. One of the important relationships they showed was the role of the thalamus in reading. Dyslexia has often been hypothesized to be rooted in the thalamus. The fact that an adult brain has been shown to respond being taught how to read in such a way as to fundamentally change that brain region suggests that some dyslexia may be attributed to a lack of plasticity in the thalamus.
What this research can't tell us is if dyslexia is caused by inborn defects in the thalamus or incorrect or somehow improper training of the thalamus early on to be able to read much later in life. One part of this puzzle that it does help us to understand is that the average person can learn to read and it's not the lack of learning that causes defects in the thalamus but likely the other way around.
There's no sign yet on how to use this research to help dyslexia, but it does start to get at the root of what causes it in some people who have it.