NEURAL CORRELATES OF THINKING IN SIGN LANGUAGE

POSITRON emission tomography (PET) was used to identify the brain regi ons activated during the 'inner signing' of sentences in subjects who were profoundly deaf and normally communicated using sign language. Al though this appeared to involve the internal representation of hand an d arm movements in space, it activated the left inferior frontal corte x rather than visuo-spatial areas. The activated region corresponds to that engaged during the silent articulation of sentences in hearing s ubjects. This suggests that 'inner signing' is mediated by similar reg ions to inner speech, and is consistent with neuropsychological data i mplicating the left hemisphere in the generation of sign language.