SIGNED AND SPOKEN LANGUAGE PERCEPTION STUDIED BY POSITRON EMISSION TOMOGRAPHY

Sign and spoken language seem to be localized in the same brain areas. They elicit similar regional cerebral blood now (rCBF) patterns, even though sign language is dependent on spatial information. We investig ated sign and spoken language perception in a group of healthy bilingu al subjects. Four videotaped activation conditions were used during PE T imaging: (1) sign language, (2) spoken language, (3) spoken language with mouth covered, and (4) spoken language on a sound track while sh owing a motionless face. Spoken language (condition 4) activated signi ficantly the perisylvian cortex (Brodmann areas 22 and 43) bilaterally . Sign language activated the visual association areas (Brodmann areas 37 and 19) but did not selectively activate parietal regions. A recip rocal relationship was observed between the level of activation in vis ual language perception areas and that-in auditory perception areas. W e conclude that when healthy bilingual subjects use the visual route f or sign language perception, the functional anatomy overlaps that of l anguage processing containing both auditory and visual components.