How Learning to Read Changes the Cortical Networks for Vision and Language

Reading, Writing, and Face Recognition Reading, not to mention writing and texting, is a relatively recent invention, and hence it is believed that a preliterate brain must adapt on the fly, so to speak, in learning how to process written words, rather than being able to rely upon evolutionarily ancient modifications of the visual system pathways. Dehaene et al. (p. 1359, published online 11 November) examined the neural response to a range of visual stimuli in three groups: illiterate adults, adults who learned to read as children, and adults who learned to read as adults. Reading induced a greater facility in processing horizontally oriented stimuli at early stages in the visual pathway and was also associated with the appearance of an area specialized for words. This gain of function appeared to occur at a cost—the area in the temporal cortex devoted to face processing shrank. Reading changes the mind. Does literacy improve brain function? Does it also entail losses? Using functional magnetic resonance imaging, we measured brain responses to spoken and written language, visual faces, houses, tools, and checkers in adults of variable literacy (10 were illiterate, 22 became literate as adults, and 31 were literate in childhood). As literacy enhanced the left fusiform activation evoked by writing, it induced a small competition with faces at this location, but also broadly enhanced visual responses in fusiform and occipital cortex, extending to area V1. Literacy also enhanced phonological activation to speech in the planum temporale and afforded a top-down activation of orthography from spoken inputs. Most changes occurred even when literacy was acquired in adulthood, emphasizing that both childhood and adult education can profoundly refine cortical organization.