Alexander S. Aruin - US grants

DESCRIPTION (Adapted from the Applicant's Abstract): This proposal will investigate central motor control mechanisms that underlie maintenance of posture. Central control of posture is expressed through anticipatory postural adjustments (APAs) that precede planned postural perturbations and minimize them with anticipatory corrections, and compensatory postural adjustments that deal with actual perturbations of balance that occur because of the suboptimal efficiency of anticipatory corrections. Recently, the Principal Investigator has developed an experimental paradigm for the investigation of anticipatory postural adjustments during self-initiated releasing of a load while standing. The paradigm allows the separation of three major factors that influence APAs: motor action, the effects of external perturbations, and postural stability. Six hypotheses clarifying the organization of anticipatory postural adjustments will be tested in eight experiments. Specific aim 1 will examine the central organization of APAs; Specific aim 2 will independently investigate the effect of each of two factors, motor action and the magnitude of perturbation upon anticipatory postural adjustments. Specific Aim 3 will investigate the effect of postural instability on anticipatory postural adjustments. Specific aim 4 will examine the effect of the relation between motor action and perturbation on anticipatory postural adjustments. It is felt that by understanding the nature of the anticipatory postural adjustments in normal adults one will be better able to understand the loss of control of posture in patients with pathology. Clinical application of the results of the study will define more precisely the focus of conventional rehabilitation strategies aimed at improving postural control in people with postural deficits.

[unreadable] DESCRIPTION (provided by applicant): Profoundly impaired mobility is a major consequence of stroke. As a result, a large number of more than 700,000 people in America sustaining a stroke each year have limitations in motor ability and compromised quality of life. It is a fact that individuals with hemiparesis frequently bear the majority of their body weight through their uninvolved lower extremity. Asymmetry of stance and weight bearing has been recognized as a predictor of the ability to ambulate. Therefore, achieving symmetry of stance and gait is considered an important goal of rehabilitation. However, therapeutic interventions designed to enhance motor function and promote independence following stroke are quite limited. We have developed a new technique that preliminary studies suggest can substantially improve gait pattern, reduce the incapacitating motor deficit of stroke patients, and increase their independence. The technique, termed Compelled Body-Weight Shift (CBWS) therapy, involves lift of the nonaffected lower extremity through the use of a shoe insert over a period of several weeks. During this time, more symmetrical weight bearing is facilitated while patients participate in physical therapy as well as regular daily activities. The proposed research builds on findings from a pilot study that demonstrated significant gains in individuals with chronic unilateral stroke following CBWS therapy. The experimental design randomly assigns patients who are more than 1 year post-stroke to two groups. The experimental group will receive CBWS therapy combined with conventional physical therapy for a period of six weeks, the control group will only receive conventional physical therapy. Immediate and longer-term (four months out) results from both groups will be compared. The specific aims are: (1) to test the efficacy of CBWS therapy compared to conventional therapy alone in improving gait and symmetry of weight bearing; (2) to evaluate whether the improvement is sustained post-CBWS therapy. This research is of paramount significance because, if successful, the outcomes from the study could be used to refocus conventional rehabilitation strategies aimed at helping chronic stroke patients to achieve maximal independence in mobility and activities of daily living. [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Profoundly impaired mobility is a major consequence of stroke. As a result, a large number of more than 700,000 people in America sustaining a stroke each year have limitations in motor ability and compromised quality of life. It is a fact that individuals with hemiparesis frequently bear the majority of their body weight through their uninvolved lower extremity. Asymmetry of stance and weight bearing has been recognized as a predictor of the ability to ambulate. Therefore, achieving symmetry of stance and gait is considered an important goal of rehabilitation. However, therapeutic interventions designed to enhance motor function and promote independence following stroke are quite limited. We have developed a new technique that preliminary studies suggest can substantially improve gait pattern, reduce the incapacitating motor deficit of stroke patients, and increase their independence. The technique, termed Compelled Body-Weight Shift (CBWS) therapy, involves lift of the nonaffected lower extremity through the use of a shoe insert over a period of several weeks. During this time, more symmetrical weight bearing is facilitated while patients participate in physical therapy as well as regular daily activities. The proposed research builds on findings from a pilot study that demonstrated significant gains in individuals with chronic unilateral stroke following CBWS therapy. The experimental design randomly assigns patients who are more than 1 year post-stroke to two groups. The experimental group will receive CBWS therapy combined with conventional physical therapy for a period of six weeks, the control group will only receive conventional physical therapy. Immediate and longer-term (four months out) results from both groups will be compared. The specific aims are: (1) to test the efficacy of CBWS therapy compared to conventional therapy alone in improving gait and symmetry of weight bearing; (2) to evaluate whether the improvement is sustained post-CBWS therapy. This research is of paramount significance because, if successful, the outcomes from the study could be used to refocus conventional rehabilitation strategies aimed at helping chronic stroke patients to achieve maximal independence in mobility and activities of daily living. [unreadable] [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Peripheral neuropathy is a significant health problem. It is not only a result of common syndromes such as diabetes, but it also remains a significant part of the aging process. Clinical neuropathies could result in ataxia, balance difficulties, and increased risk of falling. The role of sensory cues in the control of posture and balance in the presence of peripheral neuropathy is unclear. The aim of this proposal is to study the role of sensory information in balance maintenance using a novel approach, in which auxiliary sensory cues are provided to the distal segments of the leg. The PIs will evaluate changes in the postural responses of patients with diabetic peripheral neuropathy with and without auxiliary sensory cues or ankle foot orthoses. The project will provide preliminary data on the role auxiliary sensory cues play in the balance of individuals with peripheral neuropathy. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): A primary health concern for aging adults is balance deterioration, which severely limits their activities of daily living and community participation. While a decline in the ability to use compensatory (feedback) mechanisms of postural control have been studied in this population, the utilization of anticipatory (feed forward) postural adjustments in the elderly is not well documented. Inability of older adults to optimally generate postural adjustments prior to (in anticipation of) an upcoming balance threat may put them at a greater risk for losing balance. Understanding the effect of aging on the utilization of anticipatory postural adjustments in subsequent control of posture requires studying the two mechanisms together. Recently, the PIs developed a new method of applying external body perturbations that allows them to examine the individual effects of each mechanism of postural control and their interaction. Given the insufficiency of data on the anticipatory postural control in the elderly and the availability of a novel experimental technique, the objectives of this study are: 1) to provide important baseline information regarding the generation of anticipatory postural adjustments in older individuals, 2) to investigate the interaction between anticipatory and compensatory mechanisms of balance control in older adults, and 3) to examine the effect of differences in functional balance capacity of older adults on the interaction between anticipatory and compensatory mechanisms of balance control. Two specific aims will be tested in experiments involving older (functionally stable and unstable) and young adults subjected to external perturbations while standing. Electromyographic recordings, ground reaction forces, and kinematic data will be collected and analyzed. Current rehabilitation strategies in the elderly are not focused on restoration of feed forward postural control, mainly due to an inadequate understanding of the role of anticipatory postural adjustments in balance control. This study will form the foundation for a longer-term research program centered on retraining the ability of older adults to use anticipatory adjustments in maintenance and improvement of balance control. PUBLIC HEALTH RELEVANCE: The proposed project will study control of posture in the elderly. The PIs will investigate the differences in utilization of anticipatory postural adjustments between older (functionally stable and unstable) and young adults subjected to external perturbations while standing. The outcome of the study is important for the future development of therapeutic advances focused on treatment of postural disorders.