Alpha suppression during non-painful tactile stimulation

Alpha-band power is considered as a marker of sensory processing-related cortical states, including sensory suppression and the temporal organization of sensory input. This study aimed to investigate whether alpha-band power of electrophysiological brain responses is modulated by different interstimulus intervals during repetitive, non-painful tactile stimulation. Non-painful tactile stimuli were delivered to the index finger of the right hand with different interstimulus intervals (ISI) of 2 s (s), 4 s, and 8 s via a pneumatic stimulator. A separate session was conducted for each ISI in a pseudorandomized order. The electroencephalogram was recorded in all sessions with 24 volunteers. The results of the analysis showed that the alpha activity was lowest at ISI₄ and highest at ISI₈. This pattern was consistently observed in both the central and parietal regions. In the ISI₂ session, although no notable variation among the frontal, central, and parietal areas was observed, the most pronounced activity was observed in the frontal region in the ISI₄ session. The highest level of alpha activity was observed in the central area during the ISI₈ session. Variations in interstimulus intervals affect inhibitory control and sensory processing in the brain. The frontal cortex appears to manage attention and cognitive control more efficiently at intermediate intervals (ISI₄), whereas the central region shows greater involvement in processing tactile inputs at longer intervals (ISI₈).