Our experimental protocol can address whether prism adaptation therapy is effective for patients with hemispatial neglect and whether our virtual prism adaptation therapy system promotes spatial realignment and cortical activation. Virtual prism adaptation therapy was developed to be less costly, quicker to set up, and easier to adjust than conventional prism adaptation. This technique can be used to replace conventional prism therapy in patients with hemispatial neglect because it can mimic the effects of conventional prism adaptation.
This method suggests a potential for using virtual reality for stroke therapy and may give insight into hemispatial neglect rehabilitation within the virtual rehabilitation field. Although the system is based on a virtual reality gaming engine and therefore is easily used. Be sure to take care with preparation.
For functional near infrared spectroscopy measurement setup, have the participant sit in a chair with a straight back and confirm that the participant's hand will not hit the table when reaching out. Next, select the appropriate functional near infrared spectroscopy size according to the participant's head circumference and place the cap on the head of the participant so that the vertex is located at the intersection of the midpoint between the inion and nasion and the midpoint between the left preauricular and right preauricular areas. Display the montage on the screen and connect 15 sources and 24 detectors to the montage.
Use conductive gel to improve the gain from the light source if critical before inserting the optode and place the retaining cap on the participant. To set up the software, run the functional near infrared spectroscopy system software and load the neglect montage. With the montage displayed on the screen, set 15 sources and 24 detectors according to the montage and click calibrate.
To calibrate the virtual prism adaptation therapy system, first mount the virtual reality head mounted display on over the functional near infrared spectroscopy cap taking care to avoid disturbing the cap. When the display is in place, open the virtual prism adaptation therapy software and enter the participant's information. Click start and confirm the visualization of the virtual hand in the display.
Initiate the two-step calibration and instruct the participant to watch the red cross mark in the center of the screen. Then press the R key to calibrate the screen. Instruct the participant to point to the target with the right hand.
Then press the O key to calibrate the hand position. Sufficient space should be provided for calibration in the hand range and the hand should not be stretched too far to set the target position. At the end of the calibration, confirm the participant's readiness to start the experiment and start the system without the prism mode.
Click the start key to initiate an experiment with four phases simultaneously with functional near infrared spectroscopy recording and instruct the participant to point or click with their right index finger within three seconds of the appropriate icon appearing or to rest. In the virtual prism adaptation mode, the set deviation angle results in a virtual hand deviation. The green hand is the actual hand recognized position which is not shown to the user.
The blue hands are deviated hands shown to the user. In deviation mode, the user's hand extends in the left direction in order to keep the user's hand more and more close to the target. For the clicking block, instruct the participant to press the push button.
Each phase will consist of blocks for pointing, clicking, or resting. In this representative graph, the pointing error for four healthy participants is shown with the average of the median value from 10 trials in the subphase of each pointing task lasting 30 seconds. Here, the pointing error for each subject is presented demonstrating an adaptation during the virtual prism adaptation therapy phases and the post prismatic adaptation.
Use screen calibration to place the virtual space in front of the user's visual range and use target distance calibration to place the target within the reach of the user. We have studied healthy adult volunteers, but the technology could be used with clinical patients. In addition, comparison of the data with real prism classes could be meaningful.
