EEG Synchronization and Desynchronization Associated with Non-painful Thermal Stimuli

Brain processes associated with non-painful thermal stimulation in the human brain have been little studied. The electroencephalography (EEG) signal can be used to evaluate objectively the functionality of small fibers (Aδ and C) related to thermal stimulation. In the literature there is no agreement on the EEG signal modulation related to non-painful thermal stimulus. The aim of this work was to investigate the behavior of different brain rhythms of EEG signal during non-painful thermal warming and cooling stimuli. EEG signals were acquired from 14 subjects (men). The stimulus was applied to the right forearm by means of a thermode (Peltier), during a period of warming (32 ℃ → 40 ℃) and cooling (32 ℃ → 24 ℃). Event-related synchronization and desynchronization (ERS/ERD) showed a significant difference (p < 0.05), between warming and cooling, in the delta, theta and alpha bands, mainly in the ipsilateral temporal region. This finding suggests that non-painful warm and non-painful cold stimuli modulate the EEG signals differently.