title: The Localization of Long-Distance Dependency Components: Integrating the Focal-lesion and Neuroimaging Record.
abstract: In the sentence "The captain who the sailor greeted is tall," the connection between the relative pronoun and the object position ofgreetedrepresents a long-distance dependency (LDD), necessary for the interpretation of "the captain" as the individual being greeted. Whereas the lesion-based record shows preferential involvement of only the left inferior frontal (LIF) cortex, associated with Broca's aphasia, during real-time comprehension of LDDs, the neuroimaging record showsadditionalinvolvement of the left posterior superior temporal (LPST) and lower parietal cortices, which are associated with Wernicke's aphasia. We test the hypothesis that this localization incongruence emerges from an interaction of memory and linguistic constraints involved in the real-time implementation of these dependencies and which had not been previously isolated. Capitalizing on a long-standing psycholinguistic understanding of LDDs as the workings of an active filler, we distinguish two linguistically defined mechanisms:GAP-search, triggered by the retrieval of the relative pronoun, andGAP-completion, triggered by the retrieval of the embedded verb. Each mechanism is hypothesized to have distinct memory demands and given their distinct linguistic import, potentially distinct brain correlates. Using fMRI, we isolate the two mechanisms by analyzing their relevant sentential segments as separate events. We manipulate LDD-presence/absence andGAP-searchtype (direct/indirect) reflecting the absence/presence of intervening islands. Results show adirect GAP-search-LIF cortex correlation that crucially excludes the LPST cortex. Notably,indirect GAP-searchrecruitment is confined to supplementary-motor and lower-parietal cortex indicating thatGAPpresence alone is not enough to engage predictive functions in the LIF cortex. Finally,GAP-completionshows recruitment implicatingthe dorsal pathwayincluding: the supplementary motor cortex, left supramarginal cortex, precuneus, and anterior/dorsal cingulate. Altogether, the results are consistent with previous findings connectingGAP-search, as we define it, to the LIF cortex. They are not consistent with an involvement of the LPST cortex in any of the two mechanisms, and therefore support the view that the LPST cortex is not crucial to LDD implementation. Finally, results support neurocognitive architectures that involve the dorsal pathway in LDD resolution and that distinguish the memory commitments of the LIF cortex as sensitive to specific language-dependent constraints beyond phrase-structure building considerations.
authors.affiliation: Language and Brain Lab, Department of Linguistics, Yale UniversityNew Haven, CT, USA; Interdepartmental Neuroscience Program, Magnetic Resonance Research Center, Yale UniversityNew Haven, CT, USA.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Piñango
authors.affiliation: Language and Brain Lab, Department of Linguistics, Yale UniversityNew Haven, CT, USA; Interdepartmental Neuroscience Program, Magnetic Resonance Research Center, Yale UniversityNew Haven, CT, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Finn
authors.affiliation: Interdepartmental Neuroscience Program, Magnetic Resonance Research Center, Yale University New Haven, CT, USA.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Lacadie
authors.affiliation: Interdepartmental Neuroscience Program, Magnetic Resonance Research Center, Yale University New Haven, CT, USA.
authors.forename: R Todd
authors.initials: RT
authors.lastname: Constable
keywords: Broca's and Wernicke's aphasia; attention; left inferior frontal cortex; long-distance dependencies; precuneus; sentence comprehension; supplementary motor area; working memory