FMRI correlates of different components of Braille reading by the blind

Brain activations in early-blind subjects during Braille reading indicate considerable cross-modal neuroplasticity in posterior brain areas. Up to now it is, however, not clear how far such neuroplastic reorganization processes reach and whether a specific brain activation pattern corresponds to a specific component of the Braille reading task. Therefore, this fMRI study investigates whether different cortical areas are functionally specialized for different aspects of Braille reading. The comprehensive Braille reading task was contrasted to three control tasks representing subcomponents of Braille reading (passive tactile stimulation, active tactile pattern recognition, Braille imagery). Results in 14 early-blind subjects indicate that only occipital and basal temporo-occipital brain areas show specific fMRI correlates for Braille reading. Central rolandic brain activations correlated with basic somatosensory processing and superior temporal activations were associated with higher level stimulus-independent language processing. In these latter areas no indications for neuroplastic reorganizations specific for Braille reading were found, despite strong activations during the Braille reading task.