The control of posture and movement

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When a person stands in the middle of a room, they oscillate even if the task is to stand still. If the person is submitted to a reduced sensory condition (e.g. no-vision), we generally observed an increase in the amplitude and speed of the postural oscillations. A common interpretation for explaining these oscillations is that the increased sway is a direct consequence of reduced sensory inputs. Hence, the increased oscillations are associated with a less stable posture. An alternative viewpoint is that the increased sway rather reflects a mean to gain additional information by stimulating sensory receptors. These two different views are sometimes difficult to reconcile and new protocols are needed to provide insights into the control processes that could explain the nature of postural oscillations. This knowledge is essential for developing a coherent theoretical framework for understanding sway responses observed in various sensory and postural contexts, and to propose new interventions to optimize balance control. The work being proposed builds upon a recent study looking at cortical responses for naturally-occurring postural oscillations (Varghese et al. 2015). In this study, the authors selected epochs of EEG data based on the center of foot pressure (COP) velocity. Their key finding is a marked cortical negativity prior to the onset of oscillatory events that exceeded a velocity threshold (i.e. normal instability events). This work is cardinal for my proposed research program as it highlights an increased cortical contribution associated to postural reactive control. The objectives of the proposed research program is to further our understanding of the cortical contributions to balance control in conditions involving various sensory contexts not associated with an external mechanical perturbation.