Role of Altered Vision and Proprioception in Control of Posture

The primary objective of this dissertation was to investigate the role of altered vision and proprioception in the control of vertical posture. Four separate experiments involving 38 healthy subjects were conducted to study feedforward and feedback components of postural control. The experimental method involved external perturbations delivered at the shoulder level. Electrical activity of muscles and ground reaction forces were recorded and analyzed. In the first study visual acuity was altered by using differently powered glasses while the role of different visual cues (static vs. dynamic) was investigated in the second study. The third study laid insight on the role of altered proprioception in the control of posture by using miniature tendon vibrators. The outcome of the fourth and final study further established the significance of both somatosensory and proprioceptive inputs in the control of posture while maintaining balance on different support surfaces. The outcomes from these studies will help us understand how humans control their posture under conditions of altered vision and proprioception. It also provides a background for new rehabilitation interventions focused on improving balance in the elderly and patients with sensory deficits.