Corticomuscular Contributions to the Control of Rhythmic Movement in Humans

Date
2015-12-23
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Abstract
The inherent simplicity of human locomotion is deceiving in nature and its complexity becomes apparent when we observe children as they learn to walk or patients suffering from neuromuscular disorders. Human movement requires inputs from supraspinal and spinal centers as well as sensory afferent feedback. However, little is known about the interaction between cortical and muscular activity during whole body movement. This thesis aimed to investigate neuromuscular control at the muscular level, the cortical level and ultimately to link recordings from muscles and the cerebral cortex. Experiments were conducted on a cycling ergometer to mimic the rhythmic movement of limbs that is common to various forms of human locomotion such as walking, running, and cycling. Recordings of muscular activity showed that the coordinated activation of muscles reduces to a few number of critical components when the pedaling load increases. This reduction in the solution space of the task was accompanied by a more precise execution (i.e. less variability) of the chosen solutions. Recordings of electrical activity of the cerebral cortex during the pedaling movement showed that activity was located in the frontal, parietal and motor areas. The time-dependent activity in the motor areas of the cortex were linked to specific phases in the pedaling cycle. Lastly, simultaneous recordings of muscular and cortical activity showed a significant coherence between EEG signals and EMG signals. This corticospinal coupling was weakened as fatigue developed throughout the pedaling exercise. On the contrary, the information flow from the muscles to the cortex was enhanced with the development of fatigue. In summary, our results show that muscular activation patterns can be used to make inferences about neuromuscular control strategies. Further, activity in the cerebral cortex plays a role for rhythmic movement in humans and is linked to muscle activation patterns of the lower limbs.
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Keywords
Biology
Citation
Enders, H. (2015). Corticomuscular Contributions to the Control of Rhythmic Movement in Humans (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25472