Biofeedback

Visual cues are provided to a study participant to convey information about body sway in anterior-posterior and medial-lateral directions.
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Visual cues are provided to a study participant to convey information about body sway in anterior-posterior and medial-lateral directions.

In laboratory settings, wearable biofeedback devices have been shown to improve balance in young and older adults and individuals with balance impairments. However, their use requires the subject to interpret and respond to cues including visual, auditory and vibrotactile biofeedback. Vibrotactile biofeedback balance devices typically work by monitoring trunk tilt. When the tilt becomes too great, the device delivers a vibration to the area of the trunk corresponding to the direction of lean, e.g. a vibration is applied to the left side when the wearer leans too far to the left. We have performed a series of studies to quantify how individuals use and respond to vibrotactile biofeedback and will use the results to inform the design of future biofeedback systems.

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Study participant receives vibrotactile cues regarding his foot floor contact angle while walking on a treadmill.

The theory of cognitive load states that people are limited in the amount of information they can process at any given time. Therefore we sought to characterize both postural and cognitive performance during a dual-task paradigm. Elderly subjects were asked to maintain an upright stance using the biofeedback device, and to respond as quickly as possible to a choice reaction time test. The most significant finding was that reaction times were greater when vibrations were delivered during the decision-making process of the choice reaction time test. These results indicate that while biofeedback instruction increases cognitive load, it is still very effective in improving balance metrics. We hope these results can inform the future development of balance prosthetics with the specific objective of decreasing cognitive load.

Previous research has shown that in the absence of instructions subjects lean toward vibrotactile stimulation during quiet standing. We investigated the effects of attractive versus repulsive curing on balance performance during balance tasks in older adults. We found that balance performance was better with repulsive cuing suggesting that subjects interpret the cutaneous input as an alarm, overriding non-volitional sensory response.

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Customized electronics are developed to support the study of novel wearable balance devices.
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Passive markers are used to track head position during balance studies.

BIOFEEDBACK, BALANCE, AND MOTOR LEARNING (VISUAL FEEDBACK (VB))
When developing a new motor skill, there are significant differences in the body’s ability to learn depending on when biofeedback is presented. Real-time feedback informs us when we are doing something right or wrong as we are performing the skill, while results feedback tells us how we did after we’ve finished. Because both types of feedback have strengths and weaknesses depending on skill complexity, it is important to understand how each will affect the desired outcome when developing any learning program. Therefore, we are investigating the effects of real-time and results biofeedback on balance exercise performance using visual displays of body sway. Understanding these effects will help us continue to improve balance rehabilitation tools and programs.

Funding Source

NSF (GARDE 1159635 and CAREER RAPD/GARDE-0846471)NIH (5R21DC012410-02)

University of Michigan-Shanghai Jiao Tong University Collaboration on Nanotechnology for Energy and Biomedical Applications (14X1200100006)

University of Michigan Pepper Center (NIH RCDC/KL2 2P30AG024824-11)

Collaborators

Pete Shull, SJTU

Bernard Martin

April Chambers

Rakie Cham

Wendy Carender