A Serious Game for the Assessment of Visuomotor Adaptation Capabilities during Locomotion Tasks Employing an Embodied Avatar in Virtual Reality.

The study of visuomotor adaptation (VMA) capabilities has been encompassed in various experimental protocols aimed at investigating human motor control strategies and/or cognitive functions. VMA-oriented frameworks can have clinical applications, primarily in the investigation and assessment of neuromotor impairments caused by conditions such as Parkinson's disease or post-stroke, which affect the lives of tens of thousands of people worldwide. Therefore, they can enhance the understanding of the specific mechanisms of such neuromotor disorders, thus being a potential biomarker for recovery, with the aim of being integrated with conventional rehabilitative programs. Virtual Reality (VR) can be entailed in a framework targeting VMA since it allows the development of visual perturbations in a more customizable and realistic way. Moreover, as has been demonstrated in previous works, a serious game (SG) can further increase engagement thanks to the use of full-body embodied avatars. Most studies implementing VMA frameworks have focused on upper limb tasks and have utilized a cursor as visual feedback for the user. Hence, there is a paucity in the literature about VMA-oriented frameworks targeting locomotion tasks. In this article, the authors present the design, development, and testing of an SG-based framework that addresses VMA in a locomotion activity by controlling a full-body moving avatar in a custom VR environment. This workflow includes a set of metrics to quantitatively assess the participants' performance. Thirteen healthy children were recruited to evaluate the framework. Several quantitative comparisons and analyses were run to validate the different types of introduced visuomotor perturbations and to evaluate the ability of the proposed metrics to describe the difficulty caused by such perturbations. During the experimental sessions, it emerged that the system is safe, easy to use, and practical in a clinical setting. Despite the limited sample size, which represents the main limitation of the study and can be compensated for with future recruitment, the authors claim the potential of this framework as a useful instrument for quantitatively assessing either motor or cognitive impairments. The proposed feature-based approach gives several objective parameters as additional biomarkers that can integrate the conventional clinical scores. Future studies might investigate the relation between the proposed biomarkers and the clinical scores for specific disorders such as Parkinson's disease and cerebral palsy.

Evaluation of sense of position and agency in children with diplegic cerebral palsy: A pilot study.

PURPOSE: This study explores non-motor impairment of the upper dominant limb in children with diplegic cerebral palsy (CP). Specifically, it firstly investigates sense of position without visual control, ability to compare visual and proprioceptive information, and capacity to recognize effects of self-movement. Secondly, it explores the possible association between these items with cognitive function, perceptual disorder (PD), and manual ability (Manual Ability Classification System -MACS). METHODS: Ten subjects (7 female; 3 male) were tested with three protocols: the first one (A) explored sense of position, the second one (B) collimation between visual and proprioceptive information, and the last one (C) sense of agency with the use of videogames. RESULTS: All subjects executed Protocol A without making any mistakes, while in Protocol B the median percentage of mistakes was 4.8%. Mistakes were recorded more frequently in positions characterized by wrist extension. Data reported a significant correlation with Processing Speed Index (PSI). Sense of agency was positively associated with cognitive functioning, with a significant correlation with PSI.PD, MACS, and Video-Gaming Experience (VGE) showed no correlation with Protocol C. CONCLUSION: In the observed sample with diplegic CP, preliminary data support the hypothesis that there is an alteration of both sense of position and sense of agency. They were both associated to PSI, with a positive trend of correlation with cognitive functioning. PD seemed to have no influence. Further studies, with a larger sample size, a control group, and involving children without CP, are required to corroborate the results obtained.