Zusammenfassung

The human brain has the capacity to automatically compute the grammatical relations of words in sentences, be they spoken or written. This species-specific ability for syntax lies at the 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 the posterior middle temporal gyrus and superior temporal sulcus (pMTG/STS). To date, it remains unclear whether this core network for syntactic processing identified for spoken and written language in hearing people also holds for the processing of the grammatical structure of a natural sign language in deaf people. Using functional magnetic resonance imaging, a sign language paradigm that systematically varied the presence of syntactic and lexical-semantic information, and meta-analytically defined functional regions-of-interests derived from a large dataset of syntactic processing in hearing non-signers, we demonstrate that deaf native signers of German Sign Language (DGS) also recruit left pIFG and pMTG/STS for computing grammatical relations in sign language—indicating the universality of the core language network. These findings suggest that the human brain evolved a dedicated neural network for processing the grammatical structure of natural languages independent of language modality, which flexibly interacts with different externalization systems depending on the modality of language use.