title: Functional organization of the neural language system: dorsal and ventral pathways are critical for syntax.
abstract: The core of human language, which differentiates it from the communicative abilities of other species, is the set of combinatorial operations called syntax. For over a century researchers have attempted to understand how this essential function is organized in the brain. Here, we combine behavioral and neuroimaging methods, with left hemisphere-damaged patients and healthy controls, to identify the pathways connecting the brain regions involved in syntactic processing. In a previous functional magnetic resonance imaging study (Tyler LK, Wright P, Randall B, Marslen-Wilson WD, Stamatakis EA. 2010b. Reorganization of syntactic processing following left-hemisphere brain damage: does right-hemisphere activity preserve function? Brain. 133(11):3396-3408.), we established that regions of left inferior frontal cortex and left posterior middle temporal cortex were activated during syntactic processing. These clusters were used here as seeds for probabilistic tractography analyses in patients and controls, allowing us to delineate, and measure the integrity of, the white matter tracts connecting the frontal and temporal regions active for syntax. We found that structural disconnection in either of 2 fiber bundles--the arcuate fasciculus or the extreme capsule fiber system--was associated with syntactic impairment in patients. The results demonstrate the causal role in syntactic analysis of these 2 major left hemisphere fiber bundles--challenging existing views about their role in language functions and providing a new basis for future research in this key area of human cognition.
authors.affiliation: Centre for Speech, Language and the Brain, Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, UK.
authors.forename: John D
authors.initials: JD
authors.lastname: Griffiths
authors.forename: William D
authors.initials: WD
authors.lastname: Marslen-Wilson
authors.forename: Emmanuel A
authors.initials: EA
authors.lastname: Stamatakis
authors.forename: Lorraine K
authors.initials: LK
authors.lastname: Tyler
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D003071:Cognition; D063132:Connectome / Q000379:methods*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D007839:Functional Laterality; D006801:Humans; D007806:Language Disorders / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009434:Neural Pathways; D012660:Semantics; D013702:Temporal Lobe / Q000503:physiopathology*