Abstract
The human brain has the capacity to automatically compute the grammatical relations ofwords in sentences, be they spoken or written. This species-specific ability for syntax lies atthe core of our capacity for language and is primarily subserved by a left-hemispheric fronto-temporal network consisting of the posterior inferior frontal gyrus (pIFG), as well as theposterior middle temporal gyrus and superior temporal sulcus (pMTG/STS). To date, itremains unclear whether this core network for syntactic processing identified for spoken andwritten language in hearing people also holds for the processing of the grammatical structureof a natural sign language in deaf people. Using functional magnetic resonance imaging, asign language paradigm that systematically varied the presence of syntactic and lexical-semantic information, and meta-analytically defined functional regions-of-interests derivedfrom a large dataset of syntactic processing in hearing non-signers, we demonstrate that deafnative signers of German Sign Language (DGS) also recruit left pIFG and pMTG/STS forcomputing grammatical relations in sign language—indicating the universality of the corelanguage network. These findings suggest that the human brain evolved a dedicated neuralnetwork for processing the grammatical structure of natural languages independent oflanguage modality, which flexibly interacts with different externalization systems dependingon the modality of language use.