Somatosensory evoked potential compotents with and without contact cold stimulus

In the present study, somatosensory evoked potentials following contact cold painful stimulation of the posterior tibial nerve (PTN) at left and right ankle were investigated in 4 normal subjects. By fitting dipole models to independent components, more sources were found in pain status than in non pain condition. Among these fitted components, three SEPs related components and one pain related component were observed. Corresponding to the specific components, generating sources of SEPs were located at primary somatosensory cortices, anterior cingulate and thalamus, supporting the previous findings, while the pain specific generator was found at primary somatosensory cortices or primary motor cortices. However, former reports have shown more sources than those found in this study, which may be caused by overlapping of conventional SEPs and pain sources. Consequently, the connectivity of these sources will be studied to better understand the information flow and function of these components and sources.