Potential Mechanisms of Sensory Augmentation Systems on Human Balance Control

Abstract

Numerous studies have demonstrated the real-time use of visual, vibrotactile, auditory, and multimodal sensory augmentation technologies for reducing postural sway during static tasks and improving balance during dynamic tasks. The mechanism by which sensory augmentation information is processed and used by the CNS is not well understood. The dominant hypothesis, which has not been supported by rigorous experimental evidence, posits that observed reductions in postural sway are due to sensory reweighting: feedback of body motion provides the CNS with a correlate to the inputs from its intact sensory channels (e.g., vision, proprioception), so individuals receiving sensory augmentation learn to increasingly depend on these intact systems. Other possible mechanisms for observed postural sway reductions include: cognition (processing of sensory augmentation information is solely cognitive with no selective adjustment of sensory weights by the CNS), “sixth” sense (CNS interprets sensory augmentation information as a new and distinct sensory channel), context-specific adaptation (new sensorimotor program is developed through repeated interaction with the device and accessible only when the device is used), and combined volitional and non-volitional responses. This critical review summarizes the reported sensory augmentation findings spanning postural control models, clinical rehabilitation, laboratory-based real-time usage, and neuroimaging to critically evaluate each of the aforementioned mechanistic theories. Cognition and sensory re-weighting are identified as two mechanisms supported by the existing literature.

Age-related changes in leg proprioception: implications for postural control

“…Aging is associated with numerous changes in the neuromuscular system (Hunter et al 2016;Shaffer and Harrison 2007) that are accompanied by a general decline in motor performance, as reflected in a decrease in maximal muscle force (Frontera et al 1991) and force control accuracy (Baudry et al 2010;Tracy and Enoka 2002), and an increase in center of pressure excursions during unperturbed upright standing (Abrahamová and Hlavačka 2008;Laughton et al 2003;Nagai et al 2011;Van Impe et al 2013). From a clinical point of view, it is worth noting that the decrease in postural control is associated with an increased risk of falling (Horak 2006;Maki et al 1994).…”

“…In addition to revealing the capacity of the nervous system to face such a sensorimotor challenge, investigation of postural control also allows for determination of key factors for prevention and rehabilitation interventions. In this context, aging is accompanied by alterations in the proprioceptive system (Shaffer and Harrison 2007) that should contribute to changes in postural control (Anson et al 2017;Horak et al 1989).…”

Altered cortical activation after anterior cruciate ligament reconstruction during single‐leg balance task

“…In fact, the lingering deficits still lead to an upwards of 20‐fold risk of either re‐tear or contralateral ACL injury, 3‐5 or early development of knee osteoarthritis 6 . Balance is the maintenance of posture through even weight distribution, which relies on specific sensory inputs from the visual, vestibular, and somatosensory systems and appropriate motor outputs to make precise postural adjustments 7 . Individuals with chronic imbalance may rely heavier on other sensory systems to maintain postural control 7 .…”

“…Balance is the maintenance of posture through even weight distribution, which relies on specific sensory inputs from the visual, vestibular, and somatosensory systems and appropriate motor outputs to make precise postural adjustments 7 . Individuals with chronic imbalance may rely heavier on other sensory systems to maintain postural control 7 . Improved postural control has been shown with addition of visual feedback for both healthy older adults and those with balance deficits after a stroke 8 .…”

Revisión sobre la aplicación de la realidad virtual en la rehabilitación vestibular

“…Sustitución vestibular. Aunque algunos autores prefieren hablar de mecanismos de adicción sensorial, mediante la retroalimentación es posible ayudar a un sistema vestibular deficitario [17]. Destacamos las siguientes posibilidades: representan el futuro para la restitución del sistema vestibular y aunque prometedores, están aún en fase experimental hasta que se logren calibrar sin interferir con la función vestibular residual [21].…”