The human capacity for language is rooted in our ability to combine lexical items into hierarchically structured phrases and sentences, a cognitive process primarily subserved by a left-hemispheric network consisting of posterior inferior frontal gyrus (pIFG) and posterior temporal cortex (pTC; [1]). While a recent meta-analysis identified left pIFG as a modality-independent hub for processing signed, spoken, and written language [2], several studies of syntactic processing in the visuo-spatial modality of sign languages hitherto have not consistently observed left pIFG and pTC activation [3, 4, 5, 6]. Against this background, we designed an event-related functional magnetic resonance imaging experiment with deaf signers using a factorial design with two independent variables, syntax (SYN) and semantics (SEM) yielding four conditions: (i) sentences in German Sign Language (DGS) including pointing and agreement as markers of spatial syntax ([7]; +SYN +SEM); (ii) lists of unconnected DGS signs matched in length and visual complexity to the sentence stimuli (–SYN +SEM); (iii) so-called “pseudosign” sentences containing markers of spatial syntax (indexing and agreement) but devoid of lexicalized meaning due to the use of signs which do not exists in the participants’ native sign language (+SYN –SEM); and (iv) lists of unconnected “pseudosigns” with no lexicalized meaning (–SYN –SEM). Signs in the DGS conditions were drawn from [8] and controlled for iconicity, frequency, and age of acquisition. Signs and “pseudosigns” were visually matched for place of articulation across conditions. In addition, we controlled the length of the video clips and fit body-pose models [9] to identify possible differences in overall motion [10]. At the time of submission, data analysis is still ongoing. Because our experiment is the first to contrast sentence-level stimuli with lists of signs including a “pseudosign” condition (akin to Jabberwocky stimuli in research on spoken languages), we expect this manipulation to clarify the involvement of pIFG and pTC in syntactic processing in DGS independent of lexical information.