Brain Oscillatory Representations of Vibrotactile Parameters: An EEG Study

In the BCI community, haptic feedback allows us to interact with the world around us and, at the same time, perceive these interactions. For the development and maturation of neurophysiology related to haptic feedback, it is requisite to conduct more in-depth researches. To this end, we explored brain oscillatory representations of vibrotactile parameters. We utilized amplitude-modulated vibrotactile stimuli, which have four envelope frequency levels and four amplitude levels. Relevant brain oscillations in five frequency bands and ten channels were measured by noninvasive EEG technique, and they were represented in baseline-based power spectral density (PSD) forms. Results, expressed in interaction effect maps and P-value topographic maps mainly, showed that there were significant interaction effects among envelop frequency, amplitude, frequency band, and electrode position. In particular, when envelope frequency (Fe)= 40 Hz, from alpha band 1 to beta band 1, for all four amplitude levels, brain oscillations over the ipsilateral sensorimotor cortex decreased gradually. Additionally, a slight decrease of brain activation in the contralateral frontal regions was found in the two higher levels of amplitude. When amplitude (A)= 0.8 Grms, from alpha band 1 to beta band 1, for all four envelope frequency levels, brain oscillations over the bilateral sensorimotor cortex decreased gradually. In addition, a increase of brain oscillation in the frontal and parietal regions was found in the two higher envelope frequency levels. Results contribute to a deeper physiological understanding for physical vibrotactile parameters.