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Characterizing the Electrophysiology Associated With Ipsilateral Arm And Finger Movements Using ECoG in Humans
Date of Award
Doctor of Philosophy (PhD)
Movement-related cortical activity associated with the limb ipsilateral to a given cerebral hemisphere has been studied for years using multiple task paradigms, methods and measurement modalities. Conflicting results have been published related to this activity depending on the cortical location, the task complexity, and the modality used. Despite the contradicting findings, there has not been a formal comparison of human cortical electrophysiology associated with the performance of a complex motor task with either a limb ipsilateral or contralateral to a given hemisphere. This study examined cortical signals collected from human subjects who required intracranial electrode arrays for the treatment of intractable epilepsy, and related the characteristics of these signals to the subjects' upper limb movements. For aims 1 and 2, six subjects performed an eight-target center-out joystick task with the limb ipsilateral and contralateral to the hemispheric array. A direct comparison between the electrophysiology and behavioral correlates was made between data associated with an ipsilateral or contralateral limb movement. With the exception of subtle differences in the prefrontal regions, a substantial similarity between the two conditions was observed at the level of single electrodes, individual subjects and across subjects. Additionally, both conditions showed similar levels of performance in predicting various levels of task behavior (i.e. reaction time, speed and direction of movements). For aim 3, two subjects performed finger extension and flexion movements with hands either ipsilateral or contralateral to the given hemisphere. There were no statistically significant differences found between the extension and flexion movements. Moreover, the levels of activation on the ipsilateral hemisphere were much lower during this simple finger movement task, than the more engaging joy-stick task. In summary, the results of this study provide strong evidence that a given cerebral hemisphere plays an active role in both planning and executing complex arm movements ipsilateral and contralateral to the hemisphere.
Eric C Leuthardt
Daniel W Moran, Baranidharan Raman, Kilian Q Weinberger