Functional imaging techniques are being used to characterize brain activation patterns in normal subjects and individuals with neurological disorders affecting human communication. Brain activation patterns characterized using fMRI, EEG, MEG and other brain mapping techniques are used to characterize phenotypic presentation, pathophysiology and treatment of communication disorders. Structural and functional MRI studies are performed on GE and Siemens 3.0 Tesla instruments. Functional images are acquired using echoplanar imaging and arterial spin-tagging methods. Data are analyzed using MEDx, AFNI, and SPM software and newer covariance techniques developed in the Section. High density EEG studies are conducted using a Neuroscan 64 channel system and analyzed using BESA, Neuroscan and Brain Voyager packages. MEG data are collected on a 275 channel CTF instrument. Our research is aimed in large part at understanding the neural correlates of higher level, natural language use including both comprehension and production. We are particularly interested in spontaneity, communicative intent and interactions of the language system with other cognitive domains when language is used in a social context - at the level of discourse. A series of combined hemodynamic and electrophysiological studies of language use at this level in normal volunteers demonstrated unique task related patterns of brain activity that will serve as a baseline when these paradigms are used to study language recovery in post-stroke aphasia and traumatic brain injury. We are actively following an important and heretofore neglected population of aphasic patients who are """"""""recovered"""""""" at lexical and grammatical levels, but show significant and clinically relevant impairments at the discourse level. Functional and structural MRI studies evaluating relationships between discourse level symptoms and lesion location on a voxel-wise basis have been completed in this population. We also study the interactions between natural language and speech motor control in developmental stuttering. Work completed over the past several years has included functional MRI and MEG studies of confrontational naming and syntactic comprehension conducted in aphasic patients that demonstrated unique patterns of activity in perilesional and contralesional cortical regions associated with normal and abnormal language production and comprehension. MEG studies of syntactic comprehension in control subject have demonstrated differential activation associated with comprehension of simple and complex syntactic constructions. These methods will now be applied in clinical studies evaluating recovery of agrammatic aphasic patients. fMRI studies in deaf subjects using American Sign Language demonstrated modality independent features of language processing. fMRI studies in hearing subjects revealed that both spoken language and symbolic gesture activate a common left hemisphere lateralized perisylvian system. PET studies also demonstrated differences in the processing of language, melody and rhythm by deaf cochlear implant recipients. fMRI studies have demonstrated unique patterns of brain activity in trained musicians processing rhythmic stimuli. Additional studies in which fMRI and electrophysiological methods are combined to study language processing in controls and patients with speech-language disorders are being prepared for publication.
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