EEG Modulations Induced by a Visual and Vibrotactile Stimulation.

Kinesthetic motor imagery (KMI) based brain-computer interfaces hold great potential for post-stroke motor rehabilitation. However, KMI is a complex task to perform, mainly due to the absence of sensory and kinesthetic feedback. To address this issue, sensory neurofeedback solutions have been proposed. One of them is tactile vibration, which has been used in BCI paradigms, but the optimal design choices of the vibration remain unclear. In this study, we present a novel bimodal stimulus that combines a vibrotactile device for the upper limb with a visual animation of a hand grasping a bottle. We aimed to investigate the effects of four different vibration patterns and four stimulation intensities to study the effects of the stimuli on the electroencephalography (EEG) signals of 17 healthy subjects without performing KMI. Our findings revealed EEG activity in the alpha, beta, and delta frequency bands within the somatosensory cortex during the sensory stimulation. While we did not observe significant differences in brain activity among the vibration patterns, we did observe statistically significant variations based on the vibration intensity. We observed central activity in both brain hemispheres, with stronger activity occurring in the contralateral hemisphere. Additionally, EEG activity seemed to involve the contralateral occipital areas. Based on these results, it is worth considering the delivery of feedback after participants have completed KMI tasks to differentiate and comprehensively study the brain activity resulting from the mental and sensory stimulation tasks.