The neural basis of visual skill learning: an fMRI study of mirror reading.
The learning of perceptual skills is thought to rely upon multiple regions in the cerebral cortex, but imaging studies have not yet provided evidence about the changes in neural activity that accompany visual skill learning. Functional magnetic resonance imaging (fMRI) was used to examine changes in activation of posterior brain regions associated with the acquisition of mirror-reading skill for novel and practiced stimuli. Multiple regions in the occipital lobe, inferior temporal cortex, superior parietal cortex and cerebellum were involved in the reading of mirror-reversed compared to normally oriented text. For novel stimuli, skilled mirror-reading was associated with decreased activation in the right superior parietal cortex and posterior occipital regions and increased activation in the left inferior temporal lobe. These results suggest that learning to read mirror-reversed text involves a progression from visuospatial transformation to direct recognition of transformed letters. Reading practiced, relative to unpracticed, stimuli was associated with decreased activation in occipital visual cortices, inferior temporal cortex and superior parietal cortex and increased activation in occipito-parietal and lateral temporal regions. By examining skill learning and item-specific repetition priming in the same task, this study demonstrates that both of these forms of learning exhibit shifts in the set of neural structures that contribute to performance.