Grant: Discovery Grants Program - Individual

The ability to maintain balance is essential for the execution of many daily activities. While it is agreed that balance control is achieved through the integration of sensory information and the generation of appropriate motor commands, little is currently known about the specific structures within the central nervous system that are responsible for the underlying mechanisms of human balance control. Previous research have primarily focused on the processing of sensorimotor information at the spinal level but it is only recently that research have begun to recognize the importance of the supraspinal structures, particularly the cerebral cortex, for maintaining a stable upright posture. Despite this recent work, there exists many questions concerning the relative contributions of the spinal and supraspinal structures, and whether plasticity or shifts in responsibilities can occur for human balance control. Therefore, the overall objective of the proposed research program is to investigate how supraspinal and spinal structures within the central nervous system contribute to human balance control and how these contributions depend on the type, phase and constraints of the balance task. A series of experiments will be conducted whereby participants are instructed to maintain a stable upright posture while undergoing a variety of balance tasks. During these experiments, the excitability of the spinal pathways will be assessed by electrically stimulating peripheral nerves to elicit Hoffmann reflexes in the lower limb postural muscles while the involvement of the supraspinal areas will be determined by eliciting motor-evoked potentials using transcranial magnetic stimulation. Research findings from the proposed research will allow us to better localize and identify the specific locations and neural mechanisms underlying the maintenance and regulation of human balance control. Knowledge developed from the program will also improve our ability to determine how falls and balance deficits arise as a result of various physiological and contextual constraints.