Changes in sensory reweighting of proprioceptive information during standing balance with age and disease

Abstract

With sensory reweighting, reliable sensory information is selected over unreliable information during balance by dynamically combining this information. We used system identification techniques to show the weight and the adaptive process of weight change of proprioceptive information during standing balance with age and specific diseases. Ten healthy young subjects (aged between 20 and 30 yr) and 44 elderly subjects (aged above 65 yr) encompassing 10 healthy elderly, 10 with cataract, 10 with polyneuropathy, and 14 with impaired balance, participated in the study. During stance, proprioceptive information of the ankles was disturbed by rotation of the support surface with specific frequency content where disturbance amplitude increased over trials. Body sway and reactive ankle torque were measured to determine sensitivity functions of these responses to the disturbance amplitude. Model fits resulted in a proprioceptive weight (changing over trials), time delay, force feedback, reflexive stiffness, and damping. The proprioceptive weight was higher in healthy elderly compared with young subjects and higher in elderly subjects with cataract and with impaired balance compared with healthy elderly subjects. Proprioceptive weight decreased with increasing disturbance amplitude; decrease was similar in all groups. In all groups, the time delay was higher and the reflexive stiffness was lower compared with young or healthy elderly subjects. In conclusion, proprioceptive information is weighted more with age and in patients with cataract and impaired balance. With age and specific diseases the time delay was higher and reflexive stiffness was lower. These results illustrate the opportunity to detect the underlying cause of impaired balance in the elderly with system identification.

Modulation of soleus muscle H-reflexes and ankle muscle co-contraction with surface compliance during unipedal balancing in young and older adults

“…In addition to experiencing an overall increase in the challenge of controlling balance, older adults appear to be less able to adapt balance control to varying environmental conditions (Pasma et al 2015). Young adults were shown to down-modulate the soleus H-reflex between prone and standing, while older adults showed no modulation (Koceja and Mynark 2000) or even up-modulation with postural demands (Koceja et al 1995;Angulo-Kinzler et al 1998).…”

“…In upright stance, balance is challenged by gravity and the relatively high position of the body center of mass (CoM) over a small base of support. This challenge increases with impairments in neuromuscular control resulting from age or disease (Pasma et al 2015). But even for young, healthy individuals, maintenance of balance can become challenging when their base of support is reduced or when compliance of the surface which they are standing on is increased (Raymakers et al 2005;Schut et al 2017).…”

Postural Imbalance in the Elderly: Main Aspects

“…The impact on patients is comparable with that of major systemic conditions including stroke, diabetes, and arthritis. In a study in patients with cataract, Pasma et al found a higher proprioceptive weight compared with healthy elderly participants, which means that the elderly with cataract rely more on their proprioceptive information [7].…”

“…Systems can partially compensate for each other's deterioration. Failing compensation strategies may eventually result in impaired balance, which may result in falls [7].…”

Evaluation of the Dynamical Structures of Postural Control: New Insights into Motor Adaptation in Ageing and Pain

“…The coherent internal body scheme is also a reference frame to which somatosensory information is compared in order to interpret changes in body segments or upright posture (Proske & Gandevia, 2012). Ageing affects the ability to flexibly reweight proprioceptive information and this will contribute to an increased risk of falls (Eikema et al, 2013;Pasma et al, 2015). Testing balance control with different sensory challenges, such as combinations of eye closure and difference in support surface compliance has been used to evaluate balance function with ageing and neurological disorders (Horak, 1997;Sturnieks et al, 2008) and could highlight age-related issues in the ability to dynamically reweight sensory information which could underpin falls risk.…”