Feasibility study of immersive virtual prism adaptation therapy with depth-sensing camera using functional near-infrared spectroscopy in healthy adults

Abstract

Prism Adaptation (PA) is used to alleviate spatial neglect. We combined immersive virtual reality with a depth-sensing camera to develop virtual prism adaptation therapy (VPAT), which block external visual cues and easily quantify and monitor errors than conventional PA. We conducted a feasibility study to investigate whether VPAT can induce behavioral adaptations by measuring after-effect and identifying which cortical areas were most significantly activated during VPAT using functional near-infrared spectroscopy (fNIRS). Fourteen healthy subjects participated in this study. The experiment consisted of four sequential phases (pre-VPAT, VPAT-10°, VPAT-20°, and post-VPAT). To compare the most significantly activated cortical areas during pointing in different phases against pointing during the pre-VPAT phase, we analyzed changes in oxyhemoglobin concentration using fNIRS during pointing. The pointing errors of the virtual hand deviated to the right-side during early pointing blocks in the VPAT-10° and VPAT-20° phases. There was a left-side deviation of the real hand to the target in the post-VPAT phase, demonstrating after-effect. The most significantly activated channels during pointing tasks were located in the right hemisphere, and possible corresponding cortical areas included the dorsolateral prefrontal cortex and frontal eye field. In conclusion, VPAT may induce behavioral adaptation with modulation of the dorsal attentional network.

Development of a virtual reality system that generates prism adaptation for multiple motor units

“…With PA using prism glasses, posture analysis was not carried out because timecourse changes in the coordinates of body parts cannot be recorded. [8][9][10]12 Similarly, even In previous studies on VPA, 11,13,14 the subjects' postures were not measured and analyzed. Therefore, we conducted posture analysis based on the scatterplots in which controller and headset positions were projected onto a horizontal plane.…”

“…Therefore, PA tasks must be assigned directly to a target body part. Conventional PA-applicable body parts are normally limited to the limbs 5,[8][9][10][11][12][13][14]16 , on the other hand, our previous research 15 could be extended to individual motor units capable of moving quickly, such as head orientation. In the present study, body position is represented by SB, and a visible area is provided for targets; this made it possible to extend PA to a cluster of multiple motor units, such as the upper trunk system, that cannot move quickly.…”

“…9 These results showed that PA is a very promising technique for USN rehabilitation, and many further studies were conducted on the synergistic effects of PA combined with conventional USN rehabilitation methods 1 and on the clarification of the PA mechanism in experiments with healthy subjects. [10][11][12] However, the body parts to which PA applies are limited to visible limbs through prism grasses, and researchers have focused on the highly dexterous upper limbs. Thus, PA could not be applied in principle to the head and other body parts that were invisible through prism glasses.…”

“…Recently, research has been conducted on virtual prism adaptation (VPA) using virtual reality (VR) instead of prism glasses. 11,13,14 This made it possible to implement PA by means of VR devices offering a lower price and more accurate measurement instead of expensive optical devices not provided with measurement functions. However, the applicable body parts were still limited to the upper limbs.…”

Virtual reality-based sensorimotor adaptation shapes subsequent spontaneous and naturalistic stimulus-driven brain activity

“…In the past few years VRPA protocols have been tested in healthy and brain damaged populations in an effort to assess their validity, sometimes with inconsistent effects: Cho et al. (2020 , 2022 ) used a depth-sensing camera to track hand movements, while recreating classic PA settings in VR. Bourgeois et al.…”