BOLD Signal Changes in Tonic Pain
Wunderlich A, Stuber G, Klug R, Freund W
To study neural correlates of tonic pain perception, we investigated 15 healthy subjects while stimulating them electrically for 52 sec, causing tonic pain. Subjects were advised to supress pain sensation. Activation was repeated six times with 26 sec rest. Data were analysed with SPM99, modeling the activation block as early (first 13 sec) and late phase. In the group analysis, activation shifted from anterior insula in the early phase to posterior insula and primary sensory area in the late phase. The differential contrast early minus late reveals the caudate nucleus, the posterior insula dominates the opposite contrast.