The proposed research applies a resource theory to the large-scale brain network that processes language, proposing and testing a theory of the mapping between the functional processing at the cognitive level and neuronal activity at the brain level. The research examines this mapping by varying the type and amount of demand on resources and the supply of resources (as operationalized in an existing computational model) and by assessing the associated brain activation with functional Magnetic Resonance Imaging (fMRI). The studies investigate the effect of demand and type of process on the activation associated with Wernicke's area, and the relation of the language system to the more general central executive. Instead of using brain imaging to ask """"""""which brain areas activate?"""""""" We will ask """"""""to what degree does each area in the network activate under different task conditions and how do they interact as a function of resource demand and supply?"""""""" From the intensity patterns of the brain activation, we will construct models of the coordination and interaction of the underlying component processes involved in sentence comprehension, building on our existing simulation model. The studies use cutting-edge technologies and methodologies, exploiting the speed and sensitivity of echo-planar fMRI as well as behavioral studies and computational modeling to develop an integrated characterization of the relation between the cognitive processing of language and the organization of the brain systems underlying language. The research provides a direct link between brain activity and functional disorders in language processing. The approach allows the assessment of brain and cognitive function after stroke-induced aphasia, and before and after therapy. The new paradigm succeeds in identifying the location of parts of the language network in presurgical patients. Moreover, there is a clear promise of this approach helping to analyze language impairments that are less specific than aphasia, such as the disconnection facets of autism, Parkinsonian impairments of language, and diffuse diseases such as Alzheimer's.
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