title: Top-down and bottom-up modulation of pain-induced oscillations.
abstract: Attention is an important factor that is able to strongly modulate the experience of pain. In order to differentiate cortical mechanisms underlying subject-driven (i.e., top-down) and stimulus-driven (bottom-up) modes of attentional pain modulation, we recorded electric brain activity in healthy volunteers during painful laser stimulation while spatial attention and stimulus intensity were systematically varied. The subjects' task was to evaluate the pain intensity at the attended finger, while ignoring laser stimuli delivered to the other finger. Top-down (attention) and bottom up (intensity) influences differed in their effects on oscillatory response components. Attention towards pain induced a decrease in alpha and an increase in gamma band power, localized in the insula. Pain intensity modulated delta, alpha, beta and gamma band power. Source localization revealed stimulus driven modulation in the cingulate gyrus (CG) and somatosensory areas for gamma power changes. Our results indicate that bottom-up and top-down modes of processing exert different effects on pain-induced slow and fast oscillatory activities. Future studies may examine pain-induced oscillations using this paradigm to test for altered attentional pain control in patients with chronic pain.
authors.affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf Hamburg, Germany ; Department of Neurology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hauck
authors.affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Domnick
authors.affiliation: Faculty of Life Science, Laboratory of Human Biology and Physiology, Applied Science University Hamburg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lorenz
authors.affiliation: Department of Neurology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Gerloff
authors.affiliation: Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf Hamburg, Germany.
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Engel
keywords: EEG; attention; functional imaging; gamma band; pain