Description): The long-term goal of the proposed research is to characterize the deficits in both motor preparation and motor execution after unilateral brain damage and identify subsequent compensatory mechanisms employed during recovery. Normally, successful neural control of an extremity requires a complicated interplay of attentional resources, motor program selection, appropriate activation of the musculature to initiate and sustain motor execution, and online sensory feedback. Although any combination of these factors may be affected in developmental, traumatic and ischemic disorders, this proposal will focus on the effects of recruiting intact medial premotor structures on motor planning and execution of the upper limb in subjects who have suffered middle cerebral artery (MCA) stroke in either hemisphere. Functional Magnetic Resonance Imaging (fMRI) will be used to test the hypothesis that selection and execution of a bimanual motor program in response to arbitrary visual stimuli will, relative to the same task performed with only the paretic hand, selectively recruit intact medial premotor areas, including the hemisphere of the lesion. The specific effects on the musculature of actively recruited premotor structures demonstrated with fMRI will be further investigated electrophysiologically with simultaneous EEG/multiple surface EMG recordings. The investigators will test the second hypothesis that the phasic and tonic EEG/EMG couplings previously described in normal subjects will be disrupted in MCA stroke patients performing visually-guided and, to a lesser extent, ballistic movements. Furthermore, they will test the third hypothesis that the abnormalities in EEG/surface EMG couplings will be ameliorated by bimanual execution of the same visually guided and ballistic tasks. The proposed research, by demonstrating that recruitment of intact brain areas reduces functional impairment, could provide new insights into novel therapeutic strategies for patients recovering from stroke. Characterization of the changes in EEG/EMG coupling could provide a non-invasive means to monitor changes in the cortical control of the musculature with subsequent application to other areas of rehabilitation.
|Hanlon, Colleen A; Buffington, Angela L H; McKeown, Martin J (2005) New brain networks are active after right MCA stroke when moving the ipsilesional arm. Neurology 64:114-20|
|McKeown, Martin J; Hanlon, Colleen A (2004) A post-processing/region of interest (ROI) method for discriminating patterns of activity in statistical maps of fMRI data. J Neurosci Methods 135:137-47|