The effects of tactile stimulation and its imagery on sensorimotor EEG rhythms: incorporating somatic sensations in brain-computer interfaces

Abstract: Brain Computer Interface (BCIs) strive to provide a communication channel between the human brain and the environment without using overt actions. To achieve this goal, BCIs convert recordings of neural activity into commands to an external device. One of the most common BCI methods is based on matching of spectral characteristics of EEG sensorimotor rhythms (SMR) to motor imagery attempts. While such motor-imagery BCI have been extensively studied, little is known about the possibility of using tactile imagery as a BCI component. Here we studied EEG modulations associated with tactile imagery and obtained results suggesting that this approach could improve BCI operations.METHODS. 12 healthy naïve volunteers participated in the study. After vibrotactile stimulation was applied several times to the right hand, participants imagined the same sensations in the absence of actual vibration. During this tactile imagery task, 30 channels of EEG were recorded. The effects of tactile imagery were assessed as changes of the SMR in mu and beta bands, which were quantified using EEG desynchronization/synchronization (ERD/S) ratios. An offline classification was conducted for three states: resting, tactile imagery of the right hand, and tactile imagery of the left hand. The classification was based on common spatial pattern (CSP) filtering and linear discriminant analysis.RESULTS. The participants exhibited consistent contralateral ERD patterns over sensorimotor areas during tactile imagery of each hand. Statistically significant differences (p<0.05) in SMR spectral characteristics were found for the comparison of imagery condition to the control state. Offline classification exceeded chance level, as well. CONCLUSION. We found that when human subjects imagine their hands receiving tactile stimulation their SMR spectral characteristics exhibit consistent changes, which could be reliably decoded with a discrete classifier. Based on these observations, we suggest that motor-imagery BCIs could be enriched by adding a tactile-imagery component. Tactile imagery-based BCIs could be especially useful for neuroprosthetic approaches intended for people suffering from somatosensory disabilities and phantom-limb pain.ANCKLOWLEGEMENTS. The study was supported by the Russian Science Foundation grant 21-75-30024.

Keywords: tactile imagery, brain computer interfaces, sensorimotor rhythms, EEG

DOI: 10.54941/ahfe1002765

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