A Virtual reality-based System for Hand Rehabilitation and Its Impact on the Emotional and Physiological Responses of Users.

Introduction: Maintaining motivation is one of the most important characteristics of rehabilitation strategies for successful treatment. Understanding the underlying mechanism of mental state helps develop new therapeutic methods based on virtual reality (VR) and serious game technologies. The present study develops a cost-benefit game-based hand rehabilitation system and assesses the influence on the psychological state of subjects when they interact with a VR environment in different task difficulty levels. Methods: First, we introduced a low-cost smart hand rehabilitation system based on the Leap Motion Tracker. Subsequently, the experimental study was performed with 20 healthy participants. Their mental states were evoked using interaction with two separate games in four different difficulty levels. Three measures from the self-assessment manikin (SAM) self-reported test were described as a psychological response to this condition, and four features were extracted from the photoplethysmogram signal to quantify psychophysiological responses of the autonomic nervous system (ANS). Results: Comparison of the different difficulty levels revealed significant changes in arousal and dominance corresponding to the under-challenging and over-challenging conditions, respectively. The results of psychophysiological feature analysis showed significant differences only for the standard deviation of intervals between consecutive heartbeats. Conclusion: The developed system is a low-cost smart solution that can be useful for upper limb neurological rehabilitation. Regulating difficulty parameters of the implemented game can be used to influence the motivation of users through rehabilitation procedures. Photoplethysmogram is an appropriate psychophysiological indicator of mental states, but further studies are required.