neurosciencestuff:

Even learning to read in your thirties profoundly transforms brain networks

Reading is such a new ability in human evolutionary history that the
existence of a ‘reading area’ could not be specified in our genes. A
kind of recycling process has to take place in the brain while learning
to read: Areas evolved for the recognition of complex objects, such as
faces, become engaged in translating letters into language. Some regions
of our visual system thereby turn into interfaces between the visual
and language systems.

“Until now it was assumed that these changes are limited to the outer
layer of the brain, the cortex, which is known to adapt quickly to new
challenges”, says project leader Falk Huettig from the Max Planck
Institute for Psycholinguistics. The Max Planck researchers together
with Indian scientists from the Centre of Bio-Medical Research (CBMR)
Lucknow and the University of Hyderabad have now discovered what changes
occur in the adult brain when completely illiterate people learn to
read and write. In contrast to previous assumptions, the learning
process leads to a reorganisation that extends to deep brain structures
in the thalamus and the brainstem. The relatively young phenomenon of
human writing, therefore, changes brain regions that are very old in
evolutionary terms and already core parts of mice and other mammalian
brains.

“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”, says Michael
Skeide, scientific researcher at the Max Planck Institute for Human
Cognitive and Brain Sciences (MPI CBS) in Leipzig and first author of
the study, which has just been published in the renowned magazine Science Advances.
“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.” Interestingly, it seems that
the more the signal timings between the two brain regions are aligned,
the better the reading capabilities. “We, therefore, believe that these
brain systems increasingly fine-tune their communication as learners
become more and more proficient in reading”, the neuroscientist explains
further. “This could explain why experienced readers navigate more
efficiently through a text.”

Large-scale study with illiterates in India

The interdisciplinary research team obtained these findings in India,
a country with an illiteracy rate of about 39 percent. Poverty still
limits access to education in some parts of India, especially for women.
Therefore, in this study, nearly all participants were women in their
thirties. At the beginning of the training, the majority of them could
not decipher a single written word of their mother tongue Hindi. Hindi,
one of the official languages of India, is based on Devanagari, a
scripture with complex characters describing whole syllables or words
rather than single letters.

Participants reached a level comparable to a first-grader after only
six months of reading training. “This growth of knowledge is
remarkable”, says project leader Huettig. “While it is quite difficult
for us to learn a new language, it appears to be much easier for us to
learn to read. The adult brain proves to be astonishingly flexible.” In
principle, this study could also have taken place in Europe. Yet
illiteracy is regarded as such a taboo in the West that it would have
been immensely difficult to find volunteers to take part. Nevertheless,
even in India where the ability to read and write is strongly connected
to social class, the project was a tremendous challenge. The scientists
recruited volunteers from the same social class in two villages in
Northern India to make sure that social factors could not influence the
findings. Brain scans were performed in the city of Lucknow, a three
hours taxi ride away from participants’ homes.

A new view on dyslexia

The impressive learning achievements of the volunteers do not only
provide hope for adult illiterates, they also shed new light on the
possible cause of reading disorders such as dyslexia. One possible cause
for the basic deficits observed in people with dyslexia has previously
been attributed to dysfunctions of the thalamus. “Since we found out
that only a few months of reading training can modify the thalamus
fundamentally, we have to scrutinise this hypothesis”, neuroscientist
Skeide explains. It could also be that affected people show different
brain activity in the thalamus just because their visual system is less
well trained than that of experienced readers. This means that these
abnormalities can only be considered an innate cause of dyslexia if they
show up prior to schooling. “That’s why only studies that assess
children before they start to learn to read and follow them up for
several years can bring clarity about the origins of reading disorders”,
Huettig adds.