Abstract
Brain computer interfaces (BCIs) for severe stroke motor rehabilitation aim to ‘close the loop’ between attempted motor commands and sensory feedback by providing supplemental sensory information when individuals successfully establish specific brain patterns. However, previous stroke BCIs have typically employed feedback techniques with minimal biological relevance, making them difficult and unintuitive to control. To address this, we created a novel BCI that provides biologically-relevant neurofeedback in virtual reality using a head-mounted display (HMD-VR). The purpose of this experiment was to examine whether neurofeedback in HMD-VR improves BCI performance compared to the same neurofeedback presented on a normal computer screen. Twelve healthy adults were asked to control a virtual arm by imagining right hand movements, which was measured via electroencephalography (EEG) as desynchronized sensorimotor rhythms (8-30 Hz) in the left motor cortex. Participants performed two blocks of 30 trials, one for each condition (Screen, HMD-VR), counterbalanced across participants. The neurofeedback consisted of a virtual arm that moved towards or away from different targets based on the real-time EEG activity (e.g., sensorimotor desynchronization moved the arm towards the target). After completing each block, participants were asked questions relating to their sense of presence and embodiment in each environment. We found that, while participants showed similar performance on the BCI when performing the task in either environment, there was a positive correlation between performance and reported levels of embodiment, only in HMD-VR. Specifically, participants had more control over the virtual arm in HMD-VR when they reported higher levels of spatial embodiment. Furthermore, participants reported higher levels of spatial embodiment in HMD-VR compared to the computer screen. These results suggest that HMD-VR is capable of increasing levels of embodiment compared to a normal screen environment, and that increased levels of embodiment may improve performance uniquely in the HMD-VR environment. Future work will examine the effects of HMD-VR BCI on motor rehabilitation in a stroke population.