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Abstract

Explaining how humans accomplish a seemingly effortless display of elaborate movement that is well skilled, robust, and adaptable to new environments requires that we hold a
competent theory of how a complex system exploits and coordinates a large number of degrees of freedom. This motivates a well-supported framework at the behavioral level
describing motor control as encoded by modular components called motor primitives that dynamically combine to construct movement tasks. Assuming the existence of such a framework as implemented by the brain, we set out to test the hypothesis that there exists kinematically distinct motor primitives, namely, discrete and rhythmic types.
Establishing a theory that there exist kinematically distinct motor primitives, however, requires that we link psychological studies at the observational level with examinations of the neurophysiological mechanisms behind their generation. Since identifying primitives solely at the observational level remains difficult, examinations at the physiological level are needed to help resolve ambiguities. This work extends a previous study assessing the physiological significance of kinematic motor primitives by further investigating rhythmic and discrete movement tasks via a human fMRI experiment. The new experimental setup introduced includes a novel way to measure wrist exion/extention movements online within 3T and 9.4T scanners by the construction of an arm-cast measuring device that satisfies the constraints imposed by human MR environments. We outline a preliminary study examining a limited number of subjects and explain how a newly introduced data analysis method for uncovering dynamic network formation of motor tasks provides a promising direction forward.