Brain activation induced by pressure pain of healthy individuals versus amputees

Pain, as a common symptom, seriously affects the physical and mental health of individuals. This work investigated the processing mechanisms of pressure pain by combining mathematical modeling, functional Magnetic Resonance Imaging (fMRI) and Electroencephalography (EEG) methods. Differences in brain activation between healthy individuals and amputees were revealed, and EEG features for effective pain recognition were identified. The results showed that pain sensation was generated in the brain only when the output of T-cells exceeded a critical potential and that the frequency of the membrane potential and potential of T-cells increased with the intensity of pressure pain. The activation and excitatory connections in the brain changed from positive to negative as the pain intensity increased. The Prefrontal Cortex (PFC) was a core brain region activated by pressure pain, and the total activation area decreased with increasing pain intensity. Furthermore, the percentage power spectral density of the α rhythm (D_α) significantly decreased, and the percentage power spectral density of the β rhythm (D_β) significantly increased when pain was perceived. The combination of D_α and D_β effectively discriminated pain states, achieving average recognition accuracies of 94.3% for healthy individuals and 91.1% for amputees. Compared to healthy individuals, the activation area and activation intensity of the brain were lower in amputees, and the nerve pathways of amputees underwent adaptive changes, which contributed to weaker pain perception in amputees. This work contributes to revealing the processing mechanisms of pain and providing technical support for the structural control and comfort design of adaptive prosthetic sockets.