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dc.contributor.advisorMaria Mody.en_US
dc.contributor.authorSahyoun, Chérif Pen_US
dc.contributor.otherHarvard University--MIT Division of Health Sciences and Technology.en_US
dc.date.accessioned2010-04-28T17:05:55Z
dc.date.available2010-04-28T17:05:55Z
dc.date.copyright2009en_US
dc.date.issued2009en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/54589
dc.descriptionThesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2009.en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (p. 163-177).en_US
dc.description.abstractIndividuals with autism present with a constellation of social, behavioral, and cognitive symptoms. A striking characteristic is the contrast between their language and visual processing abilities. The work in this thesis combines behavioral, functional MRI, and diffusion tensor imaging methods to examine the neurobiological basis of the discrepancy between linguistic and visuospatial skills in autistic cognition. A pictorial reasoning task, designed to manipulate the degree to which language vs. visuospatial abilities may be differentially engaged in solving picture puzzles, was administered under three conditions: visuospatial, semantic and a hybrid visuospatial-cum-semantic condition. Whereas participants with Asperger's syndrome and typically developing controls (CTRL) were found to exhibit similar performance profiles, high-functioning individuals with autism (HFA) differed from these two groups: they were least efficient on the semantic condition and appeared to benefit from and favor the use of visuospatial mediation in problem solving. Results from functional MRI revealed a pattern of decreased activation in fronto-temporal language areas, and an increased reliance on posterior brain regions in the parietal and ventral temporal lobes in HFA, supporting the earlier behavioral findings. Specifically, the inferior frontal gyrus appeared to play an important role in verbal mediation and semantic integration in CTRL, whereas HFA relied more extensively on inferior and ventral regions of the temporal lobe, in keeping with a cognitive preference for visual strategies.en_US
dc.description.abstract(cont.) An examination of white matter integrity yielded a similar finding in the relationship between structural neuroanatomy and cognitive profile, such that connectivity patterns were related to the semantic mediation difficulties and visual processing preference in the HFA group: tracts relevant for semantic processing in CTRL were disrupted in HFA along the superior longitudinal fasciculus and in the frontal lobe, whereas parietal and inferior temporal white matter supporting visuospatial processing were intact in HFA The results suggest that performance in high functioning autism may be related to deficits in frontal cortex connectivity, in favor of visualization strategies in higher-level cognition. The findings appear to support the use of visuospatial vs. linguistic tasks to differentiate between potential subtypes on the autism spectrum.en_US
dc.description.statementofresponsibilityby Chérif P. Sahyoun.en_US
dc.format.extent177 p.en_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectHarvard University--MIT Division of Health Sciences and Technology.en_US
dc.titleThe neuroanatomy of pictorial reasoning in autismen_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentHarvard University--MIT Division of Health Sciences and Technology.en_US
dc.identifier.oclc569514961en_US


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