Neural substrates of the cognitive processes underlying reading: Evidence from magnetic resonance perfusion imaging in hyperacute stroke

Although it is widely agreed that reading aloud entails multiple cognitive processes, there is little evidence for localisation of these processes. We investigated regions of brain dysfunction associated with impairment of each process. Forty patients were studied within 24 hours of onset of dominant hemisphere stroke, using: (1) a battery of tasks to identify impaired processes underlying reading, and (2) magnetic resonance perfusion imaging (MRPI) and diffusion-weighted imaging (DWI). Impairment of each component of reading, except motor speech, was highly correlated with one or more regions of hypoperfusion identified by MRPI, but not with areas of infarct on DWI.