Phonological processing: say that again?

Abstract

Sensory deprivation since birth, as in blindness or deafness, produces alterations in the normal functional organization of the brain. A related question is whether cultural deprivation, such as the lack of opportunity to learn to read, could also have such effects on brain organization. Recently, Castro-Caldas et al.[ 1 Castro-Caldas A. et al. The illiterate brain: learning to read and write during childhood influences the functional organization of the adult brain. Brain. 1998; 121: 1053-1063 Crossref PubMed Scopus (304) Google Scholar ]have demonstrated, with the cooperation of a group of elderly Portuguese women, that learning to read during childhood does indeed influence the way our brains are functionally organized for spoken language. Their study used positron emission tomography to compare brain activation during word versus non-word repetition in six literate women and six women who were illiterate for social reasons. While verbally repeating words, similar areas of the brain were activated in both groups of women, whereas differences in the patterns of activation were seen during non-word repetition, the illiterate group showing increased activation (above that seen for word repetition) in the right middle frontal cortex only. In contrast, a large network of regions was activated by non-word repetition in the literate group, including bilateral insular cortex, right frontal opercular and anterior cingulate cortices, left basal ganglia, thalamus and cerebellum. This difference might reflect differences in language processing in the two groups. The illiterate women tended to transform the non-words into real words, indicating a difference in phonological processing and a reliance on lexico-semantic analysis. The authors conclude that the literate women had acquired extra language-processing abilities through the training received in reading and writing during childhood. This training appears to change permanently the functional organization of the phonological processing system in the brain.