Robot-assisted line bisection in virtual reality
This study investigated the ability to search for and reach to visual stimuli in the space surrounding bodily limbs. We adapted the classic line bisection task in a virtual reality environment for the use with patients with upper-limb sensory-motor deficits. Here, we report the results from a pre-clinical testing with healthy volunteers. Lines were projected horizontally on a semi-reflective mirror. For some of them, participants had the illusion that they were projected directly in the space surrounding one of the hands positioned passively in the device. Participants were asked to bisect the lines at their estimated midpoint by means of a robotic handle. Other factors were the hand used as active, the position of the passive hand (inside or outside of workspace), the possibility to see the hands and the location of the lines. Results showed that participants neglected the most lateral part of the lines, but only when lines were projected distantly from the body and when participants could see their hands. This study allowed us to evaluate the mechanical and cognitive constraints of reaching-to-point movements in our robot-assisted line bisection task, with the aim to control these parameters when evaluating cognitive deficits in patients with sensory-motor impairments.