Current Research Projects

Maintaining balance during locomotion is a complex task with requirements and constraints that change during the gait cycle. To understand the control actions employed by the central nervous system (CNS) to achieve this, we induce illusions of falling and observe how the motor system responds. We prefer sensory perturbations to induce illusory falls rather than mechanical perturbations to induce real falls, because in the latter case it is hard to distinguish between purely mechanical, passive effects of the perturbation on the body and active responses from control action taken by the CNS.

Injuries from falls are a major public health issue. Falls often occur when the environment restricts the range of possible movements and drives the walking human out of the safety zone into less stable behavior. We use obstacles obstructing a walkway as a basic model of interactions between the balance system and environmental constraints. Stepping over an obstacle is a complex behavior, with a multitude of different aspects such as horizontal distance to the obstacle before and after the step, vertical clearance of the ankle and toes when passing the obstacle, development of the ground reaction forces under the stance foot, and total time for stepping over. These aspects interact with each other in non-trivial ways. For instance, the total time used for a step is increased when stepping over a higher obstacle, but not when taking a longer step over a more distant obstacle. Increases in step time shifts the relative importance between the different mechanisms of balance control (link). The stance foot ankle strategy becomes more important for longer steps. Observing changes in the relevant balance responses, e.g. the stance foot ground reaction forces, provides a way to understand how the motor plans accommodate different balance requirements imposed by the environment.

Cerebral Palsy (CP) is a group of disorders affecting the development of movement and posture and is characterized by many functional impairments of which include poor balance, difficulties in gait and deterioration of ambulatory ability over time. Traditional rehabilitation and motor learning approaches in CP are generally motor-centric focusing on techniques to ameliorate musculoskeletal and motor impairments. It is unknown if impaired somatosensory processing can be modulated in children with CP to enhance postural control. This project uses a sensor fusion paradigm to investigate potential deficits in the dynamic integration of visual, vestibular and proprioceptive modalities that contribute to balance. Stochastic resonance (SR) stimulation, which has been shown to reduce postural sway in individuals with proprioceptive deficits, will then be used to potentiate the effects of existing treatment strategies for improving balance and motor control.

Previous research investigating visual feedback and postural control has focused on static posture while subjects attempt to keep their center of pressure on a visual target on a computer screen. This method of application has been met with mixed results regarding improvements in balance ability. This may be related to the variable that is controlled by the feedback, or the method of feedback training. Moreover, most falls occur during movement or during transitions from stationary positions to moving activities. The purpose of this project is to improve balance control during walking through the use of a novel application of visual feedback. Subjects walk on a treadmill in front of a LCD TV with feedback about trunk movement displayed relative to a target. Older adult subjects with balance difficulties are recruited in an intervention consisting of 4 weeks of visual feedback training on a treadmill 3 times per week. Participants will be tested using standard clinical assessments of balance and gait pre- and post- intervention.