Effects of attention on visceral stimulus intensity encoding in the male human brain.
OBJECTIVE
Hypervigilance is considered important in pain perception in functional gastrointestinal disorders. Nonetheless, a comprehensive assessment of the influence of attention on brain processing of visceral sensation has not been performed. We investigated the effects of attention on esophageal pain perception and brain activity.


METHODS
Twelve healthy male volunteers (age range, 21-32 years) underwent 4 functional magnetic resonance imaging scans incorporating 4 levels of esophageal stimulation (ES), ranging from nonpainful to painful, during which they completed a task aimed at distracting them from the esophageal stimulus. The volunteers were then scanned a fifth time, during painful stimulation without distraction.


RESULTS
Following ES during distraction, there was a significant linear trend (P < .05) in which the intensity of cerebral activation in the primary somatosensory cortex (SI) (bilateral) and left mid-anterior cingulate cortex (ACC) increased with stimulation intensity. When pain was delivered during distraction, there was a significant reduction in pain ratings, accompanied by significant decreases (P < .05) in brain activity in the right ACC and right prefrontal cortex. There was no effect of distraction on SI activity (P < .05).


CONCLUSIONS
Our results suggest that the SI is involved in processing sensory-discriminative aspects of visceral sensation. In contrast, activity in the mid-ACC suggests that this region is multifunctional because it appears to be involved in sensory and cognitive appraisal of visceral pain; the right prefrontal cortex seems to be involved in only cognitive responses to pain.
Wingate Institute for Neurogastroenterology, Queen Mary University of London, London, United Kingdom. s.j.coen@qmul.ac.uk
Steven J
SJ
Coen
Qasim
Q
Aziz
Lidia
L
Yágüez
Mick
M
Brammer
Steven C R
SC
Williams
Lloyd J
LJ
Gregory
D000328:Adult; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D004947:Esophagus / Q000294:innervation*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D010812:Physical Stimulation; D012016:Reference Values; D013003:Somatosensory Cortex / Q000503:physiopathology; D055815:Young Adult