The cross-modal interaction between pain-related and saccade-related cerebral activation: a preliminary study by event-related functional magnetic resonance imaging.
Pain-related cerebral activation in functional magnetic resonance imaging shows less consistent signals that decay earlier than in conventional task-related activation. This may result from pain's top-down inhibition mediated by cognitive or hemodynamic interaction that could affect activation by other modalities. Using event-related functional magnetic resonance imaging, we examined whether pain affects cerebral activation by a saccade task through such cross-modal interaction. Six right-handed volunteers underwent whole-brain echo-planar imaging on a 3.0 T magnetic resonance imaging scanner while they received thermal pain stimulus at 50 degrees C on the right forearm (P; n = 6), performed a visually guided saccade task (V; n = 6), and went through a simultaneous pain-plus-saccade paradigm (PV; n = 5). Averaged functional activation maps were synthesized and signal time courses were analyzed at activation clusters. P activated the bilateral secondary somatosensory cortex (S2). V activated the posterior, supplementary, frontal eye fields, and visual areas. PV enhanced the S2 activation and activated additional pain-related areas, including the bilateral premotor area, right insula, anterior, and posterior cingulate cortices. In contrast, V-related activation was attenuated in PV. We propose that pain caused cross-modal suppression on the oculomotor activity and that an oculomotor task enhanced pain-related activation by triggering attention toward pain.


CONCLUSIONS
Pain-related cerebral activation is enhanced by attention toward pain. It may involve top-down suppression over the unrelated neural networks of saccade.
Kurata
Jiro
J
*Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA; †Departments of Radiology, Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL.
Thulborn
Keith R
KR
Firestone
Leonard L
LL
D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*
D010100:Oxygen