Functional Neuroimaging Studies

Deafness &Other Communication Disorders

Investigators

Linked publications & trials

Abstract

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. fMRI studies are performed on 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, IDL, 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. PET studies of narrative production in subjects fluent in English and ASL revealed common activations in a widespread array of regions and suggest a novel model for lateralization of cerebral activity during the generation of discourse. This pattern is not predicted by the standard Wernicke-Geschwind model, and may become apparent when language is produced in an ecologically valid contex (Brain, 124: 2028-44, 2001). A functional MRI study of cross-categorical picture and word processing provided data suggesting that the left occipitotemporal and right temporal cortices are part of a neural network mediating picture-word conversions, whereas the frontal cortex functions as a central executive coordinating these transformations (Human Brain Mapping, 16:168-75, 2002). An additional fMRI study demonstrated the hemodynamics of the electrophysiological mismatch negativity (Int J Neuroscience 112:587-606, 2002). PET studies in deaf subjects using American Sign Language demonstrated modality independent features of language processing, strongly lateralized to the left hemisphere regardless of the hand used in signing (Journal of Cognitive Neuroscience, In Press). Another PET study demonstrated differences in the patterns of brain activity underlying consciousness and alertness (Brain, 125: 2308-2319, 2002). A number of additional studies in which fMRI and EEG methods are combined to study language processiig in controls and aphasic are being prepared for publication.