Three-dimensional grammar in the brain: Dissociating the neural correlates of natural sign language and manually coded spoken language

• Published in: Neuropsychologia Vol. 71; no. May; pp. 191 - 200
• Main Authors: Jednoróg, Katarzyna, Bola, Łukasz, Mostowski, Piotr, Szwed, Marcin, Boguszewski, Paweł M., Marchewka, Artur, Rutkowski, Paweł
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2015
• Subjects: Adult; Brain - physiopathology; Brain Mapping; Deaf; Deafness - physiopathology; Female; fMRI; Humans; Language; Language comprehension; Magnetic Resonance Imaging; Male; Motion Perception - physiology; Neuropsychological Tests; Pattern Recognition, Visual - physiology; Poland; Sign Language; Signed oral language; Young Adult; Poland; CC; fMRI; Language comprehension; Sign language; PJM; Signed oral language; Deaf; SJM
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2015.03.031

In several countries natural sign languages were considered inadequate for education. Instead, new sign-supported systems were created, based on the belief that spoken/written language is grammatically superior. One such system called SJM (system językowo-migowy) preserves the grammatical and lexical structure of spoken Polish and since 1960s has been extensively employed in schools and on TV. Nevertheless, the Deaf community avoids using SJM for everyday communication, its preferred language being PJM (polski język migowy), a natural sign language, structurally and grammatically independent of spoken Polish and featuring classifier constructions (CCs). Here, for the first time, we compare, with fMRI method, the neural bases of natural vs. devised communication systems. Deaf signers were presented with three types of signed sentences (SJM and PJM with/without CCs). Consistent with previous findings, PJM with CCs compared to either SJM or PJM without CCs recruited the parietal lobes. The reverse comparison revealed activation in the anterior temporal lobes, suggesting increased semantic combinatory processes in lexical sign comprehension. Finally, PJM compared with SJM engaged left posterior superior temporal gyrus and anterior temporal lobe, areas crucial for sentence-level speech comprehension. We suggest that activity in these two areas reflects greater processing efficiency for naturally evolved sign language. •Comprehension of natural vs. devised sign systems in deaf was studied with fMRI.•Natural sign language but not the devised system contains classifiers constructions.•Comprehension of classifier constructions engages bilateral parietal areas.•Reduced activity in the left posterior STG was observed for the devised system.