A brain signature for literacy

Not Exactly Rocket Science covers a fantastic study on how the structure of the brain changes as illiterate adults learn to read and write. The research was conducted on rather a novel group of participants. Most were ex-members of guerilla forces in Colombia that had recently put down their weapons to re-integrate in society.

Colombia has a sizeable program to rehabilitate ex-paramilitary ‘reinsertados’ that includes social support and education, as many have never attended school. As the researchers note, this sets up an interesting natural experiment:

After decades spent fighting, members of the guerrilla forces have begun re-integrating into mainstream Colombian society, introducing a sizeable population of illiterate adults who have no formal education. Upon putting down their weapons and returning to society, some had the opportunity to learn to read for the first time in their early twenties, providing the perfect natural situation for experiments investigating structural brain differences associated with the acquisition of literacy in the absence of other types of schooling or maturational development.

The researchers, led by neuroscientist Manuel Carreiras, recruited a group of ex-paramilitaries who could read less than five simple words on a Spanish reading and writing test, and compared them to a similar group who learnt to read and write from an early age.

The research team use MRI scans to compare differences in brain structure between the two groups to allow an insight into how brain anatomy changes to accommodate reading and writing.

While it is possible to do this with children, it is almost impossible to separate out which are the brain changes due specifically to acquiring literacy and which are just part of the massive changes that constantly take place as children develop.

The images above show the areas of the brain (in orange) where the structure was significantly different between literate and illiterate adults.

Rather neatly, these are also areas that have been identified in brain activation studies of reading and writing, and are known to be associated with visual perception, processing word sounds and dealing with the meaning of words.

Subsequent analyses showed that pathways the angular gyrus, a key language area, across each hemisphere were less developed in illiterate adults and were less active when the participants were asked to name objects.

A brilliantly innovative study, a good write-up from Not Exactly Rocket Science and perfectly timed for my arrival in Colombia.

Link to NERS on guerilla reading.
Link to summary of scientific paper.

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