The neural correlates for spatial language: Perspective-dependent and -independent relationships in American Sign Language and spoken English.

In American Sign Language (ASL) spatial relationships are conveyed by the location of the hands in space, whereas English employs prepositional phrases. Using event-related fMRI, we examined comprehension of perspective-dependent (PD) (left, right) and perspective-independent (PI) (in, on) sentences in ASL and audiovisual English (sentence-picture matching task). In contrast to non-spatial control sentences, PD sentences engaged the superior parietal lobule (SPL) bilaterally for ASL and English, consistent with a previous study with written English. The ASL-English conjunction analysis revealed bilateral SPL activation for PD sentences, but left-lateralized activation for PI sentences. The direct contrast between PD and PI expressions revealed greater SPL activation for PD expressions only for ASL. Increased SPL activation for ASL PD expressions may reflect the mental transformation required to interpret locations in signing space from the signer's viewpoint. Overall, the results suggest both overlapping and distinct neural regions support spatial language comprehension in ASL and English.