Brain systems mediating semantic and syntactic processing in deaf native signers: Biological invariance and modality specificity

doi:10.1073/pnas.0809609106

Brain systems mediating semantic and syntactic processing in deaf native signers: Biological invariance and modality specificity

^aSchool of Psychological Sciences, University of Manchester, Zochonis Building, Manchester M13 9PL, United Kingdom;
^bDepartment of Psychology, State University of New York at New Paltz, 600 Hawk Drive, New Paltz, NY 12561;
^cDepartment of Psychology, Psychiatry, and Surgery, Neuroscience Institute, and Brain Repair Centre, Dalhousie University, Halifax, NS, Canada B3H 4J1;
^dDepartment of Linguistics, Cognitive Neuropsychology Laboratory, University of Washington, Seattle, WA 98195;
^eCenter for Mind and Brain, University of California, 267 Cousteau Place, Davis, CA 95618;
^fDepartment of Biological Psychology and Neuropsychology, University of Hamburg, Von-Melle-Park 11, 20146 Hamburg, Germany; and
^gDepartment of Psychology, 1227 University of Oregon, Eugene, OR 97403

Edited by Michael I. Posner, University of Oregon, Eugene, OR, and approved March 31, 2009 (received for review October 10, 2008)

Abstract

Studies of written and spoken language suggest that nonidentical brain networks support semantic and syntactic processing. Event-related brain potential (ERP) studies of spoken and written languages show that semantic anomalies elicit a posterior bilateral N400, whereas syntactic anomalies elicit a left anterior negativity, followed by a broadly distributed late positivity. The present study assessed whether these ERP indicators index the activity of language systems specific for the processing of aural-oral language or if they index neural systems underlying any natural language, including sign language. The syntax of a signed language is mediated through space. Thus the question arises of whether the comprehension of a signed language requires neural systems specific for this kind of code. Deaf native users of American Sign Language (ASL) were presented signed sentences that were either correct or that contained either a semantic or a syntactic error (1 of 2 types of verb agreement errors). ASL sentences were presented at the natural rate of signing, while the electroencephalogram was recorded. As predicted on the basis of earlier studies, an N400 was elicited by semantic violations. In addition, signed syntactic violations elicited an early frontal negativity and a later posterior positivity. Crucially, the distribution of the anterior negativity varied as a function of the type of syntactic violation, suggesting a unique involvement of spatial processing in signed syntax. Together, these findings suggest that biological constraints and experience shape the development of neural systems important for language.

Footnotes

¹To whom correspondence should be addressed. E-mail: cheryl.capek{at}manchester.ac.uk
Author contributions: D.C., B.R., and H.J.N. designed research; C.M.C., G.G., A.J.N., and S.L.M. performed research; C.M.C. analyzed data; and C.M.C., G.G., A.J.N., D.C., B.R., and H.J.N. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0809609106/DCSupplemental.