The French have always been snobs for literacy. When a guest visits you in your house, the Californian will first look what car you drive, the German will look for any dust, and the French will check the books in your library. Thus, it is not surprising it was a French team of researchers to study how learning to read changes the cortical networks for vision and language.
Virtually all adult neuroimaging experiments are performed in highly educated college students. The observed brain architecture therefore reflects the influence of culture and education over and above spontaneous brain development. Thus, the researchers asked: "Does literacy improve brain function? Does it also entail losses?" Using functional magnetic resonance imaging, they measured brain responses to spoken and written language, visual faces, houses, tools, and checkers in adults of variable literacy.
The conclusion of their research is that literacy, whether acquired in childhood or through adult classes, enhances brain responses in at least three distinct ways. First, it boosts the organization of visual cortices. Second, literacy allows virtually the entire left-hemispheric spoken language network to be activated by written sentences. Thus reading, a late cultural invention, approaches the efficiency of the human species' most evolved communication channel, namely speech. Third, literacy refines spoken language processing by enhancing a phonological region, the planum temporale, and by making an orthographic code available in a top-down manner.