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 PET, fMRI, EEG, MEG and other brain mapping techniques are used to characterize phenotypic presentation, pathophysiology and treatment of communication disorders. PET scans are performed on the GE Advance and Scanditronix PC2048-15B tomographs using the H215O and C-11 Raclopride methods. Data are analyzed using Statistical Parametric Mapping software and newer covariance techniques developed in the section. Structural and functional MRI studies are performed on GE 1.5 and 3.0 Tesla instruments. Functional images are acquired using spiral, 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. A series of combined hemodynamic and electrophysiological studies of language in normal volunteers demonstrated unique task related patterns of brain activity for reading, naming, and semantic processing that will serve as a baseline when these paradigms are used to study language recovery in post-stroke aphasia. An arterial spin labeling and BOLD fMRI studies have yielded good results for studying continuous speech with this method, that will be useful in studying discourse level language production in controls, aphasics and stuttering subjects as well. Structural MRI studies evaluating relationships between aphasic symptoms and lesion location on a voxel-wise basis have been completed. Functional MRI and MEG studies of confrontational naming and syntactic comprehension conducted in aphasic patients have 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. A number of additional studies in which fMRI and electrophysiological methods are combined to study language processing in controls and aphasic are being prepared for publication.
Showing the most recent 10 out of 35 publications
