Effect of vibrotactile feedback and perception induced by transcranial magnetic stimulation over the primary motor cortex in virtual hand illusion

Noninvasive brain stimulation has the potential to revolutionize the way we interact with virtual environments by inducing tactile sensations. In this study, we conducted a virtual hand illusion experiment to investigate how the induced embodiment in virtual reality using brain stimulation differs from that using traditional haptic devices. The haptic glove was used to provide vibrotactile feedback, while the noninvasive brain stimulation was achieved through transcranial magnetic stimulation (TMS) to elicit hand movement and sensation. We compared the proprioceptive drifts resulting from the changes in ownership and body representation. Both the TMS and vibrotactile methods showed a similar tendency of moving toward the virtual hand, indicating the successful induction of the illusion of embodiment. The drifts were 21.9 mm and 30.7 mm for the vibrotactile and the TMS-evoked perception, respectively. Questionnaire results about ownership significantly favored the synchronous condition of visual and haptic sensations compared to the asynchronous condition. Our results demonstrate the feasibility of using TMS-based virtual reality to enhance the illusion effect, offering new possibilities for improved interactions in virtual environments.