Mechanisms of Sensory Integration During Postural Adaptation

The body schema is an internal representation of the position of one’s body in relationship to the environment. Adaptation of the body schema involves an update of this internal model in response to changes in the task or the environment. Plasticity of the body schema during postural control allows for one to adapt to changes or hazards in their environment. The level of plasticity is related to the efficiency of integration of sensory feedback in the cortex. This investigation sought to improve the understanding of postural adaptation by identifying the impact of sensory reweighting during a postural adaptation task. Additionally, this investigation sought to identify the effects of bilateral neuromodulation of the posterior parietal cortex (PPC) using transcranial direct current stimulation (tDCS) on postural adaptation. We proposed three experiments to accomplish these goals. During the first experiment, we presented tendon vibration during an incline-intervention, which results an adaptation consisting of an anterior shift in position known as lean after-effect (LAE). During the second experiment, we presented tendon vibration after an incline-intervention. During the third experiment, we performed tDCS prior to an incline-intervention. Primary analyses of the data collected during this investigation revealed that an inclined support surface altered subjects’ response to vibration. We also found that vibration during an inclined stance did not alter the development of LAE, but vibration during the after-effect period had direction specific effects. Last, we found that neuromodulation of the PPC led to alterations in LAE. Results of this dissertation identified effects of proprioceptive reliability on the development of postural adaptation induced by an incline-intervention. Furthermore, this dissertation identified the direction specific results of altered support surface inclination on the effects of tendon vibration, providing new insights to this line of research. Results also help to improve the understanding of the role of the PPC in postural adaptation associated with adaptation of the body schema. These insights may lead to improvements in understanding of the role of the body schema in postural control, which may lead to improvements in strategies for the maintenance and rehabilitation of postural control in aging and disabled populations.