An fMRI study of activation of SII and adjacent cortices elicited by median nerve stimulation at different stimulus intensities

摘要

The effect of stimulus intensity on the responses of the SII cortex to electric median nerve stimulation was investigated by means of fMRI. The aim of this study was principally at detecting a variation in the activated areas in the secondary somatosensory cortex when the stimulus intensity increased approaching the pain threshold. Evidence for a different pattern of activated areas in SII cortex was found when comparing non-painful stimulation (at motor threshold) with a slightly painful stimulation. This result suggests that tactile, proprioceptive and pain fibers project to different areas in the SII cortex.