Effects of Sensorimotor Perturbations on Balance Performance and Electrocortical Dynamics

Virtual reality has been increasingly used in research on balance rehabilitation because it provides robust and novel sensory experiences in controlled environments. We studied 19 healthy young subjects performing a balance beam walking task in two virtual reality conditions and with unaltered view (15 minutes each) to determine if virtual reality high heights exposure induced stress. We recorded number of steps off the beam, heart rate, electrodermal activity, response time to an auditory cue, and high-density electroencephalography (EEG). We hypothesized that virtual high heights exposure would increase measures of physiological stress compared to unaltered viewing at low heights. We found that the virtual high height condition increased heart rate variability and heart rate frequency power relative to virtual low heights. Virtual reality use resulted in increased number of step-offs, heart rate, electrodermal activity, and response time compared to the unaltered viewing at low heights condition. Our results indicated that virtual reality decreased dynamic balance performance and increased physical and cognitive loading compared to unaltered viewing at low heights. In virtual reality, we found significant decreases in source-localized EEG peak amplitude relative to unaltered viewing in the anterior cingulate, which is considered important in sensing loss of balance. Our findings indicate that virtual reality provides realistic experiences that can induce physiological stress in 1 This chapter has been previously published in PLoS One (Peterson, Furuichi, & Ferris, 2018). 8 humans during dynamic balance tasks, but virtual reality use impairs physical and cognitive performance during balance. Introduction Humans regularly perform activities of daily living and tasks of mobility that require maintenance of dynamic balance. With human aging, balance control can deteriorate (Kanekar & Aruin, 2014), leading to falls and other serious consequences (Sterling, O'Connor, & Bonadies, 2001). In addition, falls can induce a fear of falling again, potentially leading to a loss of independence (Lach, 2005). Balance training often reduces the risk of falling (Carter, Kannus, & Khan, 2001; Kannus, Sievänen, Palvanen, Järvinen, & Parkkari, 2005), even more than basic walking tasks (Sherrington, et al., 2008). Balance training equipment varies widely from wobble boards (Ogaya, Ikezoe, Soda, & Ichihashi, 2011) to complex balance systems (Ibrahim, Mattar, & Elhafez, 2016). Because integrating balance training into everyday activities reduces falls (Clemson, et al., 2012), virtual reality has been used to motivate users to perform challenging balance tasks in realistic scenarios (Duque, et al., 2013; Kalron, Fonkatz, Frid, Baransi, & Achiron, 2016). Dynamic training in virtual reality has improved walking speed for Parkinson’s patients (Mirelman, et al., 2011) and walking stability for stroke patients (Darekar, McFadyen, Lamontagne, & Fung, 2015). However, many studies project virtual environments onto a screen, which does not move with the user and allows the user to look away (Booth, Masud, Connell, & Bath-Hextall, 2013; Corbetta, Imeri, & Gatti, 2015). Virtual reality presented using a headmounted display may provide more effective immersion.