Arthur D. Kuo - US grants

9511814 Kuo The goal of this research project is to understand how the human brain puts together thousands of pieces of information from sensors throughout the body, such as eyes, the inner ear, and receptors in joints and muscles, to form a picture of where the limbs are and how they are moving. This information is used for planning and control of movement. It is a process that the brain carries out subconsciously; it is critically important for proper balance, to keep up from falling; it provides athletes with the ability to move fluidly and skillfully and allows seamen and astronauts to adjust movements to their new environments. The approach used in this study is to integrate techniques from two scientific fields. Physiological studies describe how signals are produced by the sensors and define the places in the brain where these signals are transmitted. Control engineering describes how signals of many types can be used to perform a useful task. In this project, physiologists and control engineers will work together to examine the differences in balance control in astronauts before and after spaceflight. The adaptations that take place during spaceflight make it possible to determine some of the factors that are and are not relevant to control of moment and, therefore, to explain some of the basic mechanisms underlying control of movement.

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand how humans continuously stabilize their bodies while walking. Balance is necessary to prevent falling, an issue relevant to the rehabilitation of individuals with vestibular and other sensory impairments, as well as elderly adults who suffer from decreased sensory function. Although a great deal is known about postural balance while standing, less is known about balance while walking, because translation of the body makes it more difficult to make measurements and apply perturbations. We will develop a new experimental device that will make it possible to manipulate balance during walking, so that the resulting human control responses can be measured. We will then use this device to study common gait adaptations such as to step length and step width, and their impact on stability. These adaptations will be studied in both young and elderly subjects. The Specific Aims of this project are: 1. To design and fabricate an active device that can externally stabilize or de-stabilize the body during treadmill walking, for use in testing and assessing control of balance. This device will provide a means to experimentally manipulate the body's degree of stability, or apply small perturbations during walking. 2. To determine the relationship between the degree of body instability and characteristics of walking such as step length and width, step variability, and metabolic cost. We will test the hypothesis that these characteristics are interrelated due to the need to control balance by adjusting gait parameters and foot placement. 3. To perform a system identification of the human control system that stabilizes balance during walking. We will use the external stabilization/de-stabilization device to apply small noise-like perturbations to subjects walking on a treadmill, measure their associated control responses, and identify the systematic feedback responses that are used to maintain continuous stability during walking.