The Cortical Organization of Syntactic Processing Is Supramodal: Evidence from American Sign Language

摘要

Areas within the left-lateralized neural network for languagehave been found to be sensitive to syntactic complexity in spokenand written language. Previous research has revealed thatthese areas are active for sign language as well, but whetherthese areas are specifically responsive to syntactic complexityin sign language independent of lexical processing has yet tobe found. To investigate the question, we used fMRI to neuroimagedeaf native signers’ comprehension of 180 sign strings inAmerican Sign Language (ASL) with a picture-probe recognitiontask. The ASL strings were all six signs in length but varied at threelevels of syntactic complexity: sign lists, two-word sentences, andcomplex sentences. Syntactic complexity significantly affectedcomprehension and memory, both behaviorally and neurally,by facilitating accuracy and response time on the picture-proberecognition task and eliciting a left lateralized activation responsepattern in anterior and posterior superior temporal sulcus (aSTSand pSTS). Minimal or absent syntactic structure reducedpicture-probe recognition and elicited activation in bilateralpSTS and occipital-temporal cortex. These results provide evidencefrom a sign language, ASL, that the combinatorial processingof anterior STS and pSTS is supramodal in nature.The results further suggest that the neurolinguistic processingof ASL is characterized by overlapping and separable neural systemsfor syntactic and lexical processing.