TY - JOUR
T1 - Temporal summation of heat pain in humans
T2 - Evidence supporting thalamocortical modulation
AU - Tran, Tuan D.
AU - Wang, Heng
AU - Tandon, Animesh
AU - Hernandez-Garcia, Luis
AU - Casey, Kenneth L.
N1 - Funding Information:
This work was supported by the Dept. of Veteran’s Affairs, the Veteran’s Educational and Research Association of Michigan, NIH Grant AR46045 (K.L.C.); Bonica (IASP), IBRO and WHO/NINDS Fellowships (T.D.T.), and University of Michigan Medical School SBRP Fellowship (A.T.). The authors declare no conflict of interest, financial or otherwise, with the content or funding of the research described in this report. The authors thank Susan King for technical support and Dr. Richard Gracely for helpful suggestions on earlier versions of this report.
PY - 2010/7
Y1 - 2010/7
N2 - Noxious cutaneous contact heat stimuli (48 °C) are perceived as increasingly painful when the stimulus duration is extended from 5 to 10 s, reflecting the temporal summation of central neuronal activity mediating heat pain. However, the sensation of increasing heat pain disappears, reaching a plateau as stimulus duration increases from 10 to 20 s. We used functional magnetic resonance imaging (fMRI) in 10 healthy subjects to determine if active central mechanisms could contribute to this psychophysical plateau. During heat pain durations ranging from 5 to 20 s, activation intensities in the bilateral orbitofrontal cortices and the activation volume in the left primary (S1) somatosensory cortex correlated only with perceived stimulus intensity and not with stimulus duration. Activation volumes increased with both stimulus duration and perceived intensity in the left lateral thalamus, posterior insula, inferior parietal cortex, and hippocampus. In contrast, during the psychophysical plateau, both the intensity and volume of thalamic and cortical activations in the right medial thalamus, right posterior insula, and left secondary (S2) somatosensory cortex continued to increase with stimulus duration but not with perceived stimulus intensity. Activation volumes in the left medial and right lateral thalamus, and the bilateral mid-anterior cingulate, left orbitofrontal, and right S2 cortices also increased only with stimulus duration. The increased activity of specific thalamic and cortical structures as stimulus duration, but not perceived intensity, increases is consistent with the recruitment of a thalamocortical mechanism that participates in the modulation of pain-related cortical responses and the temporal summation of heat pain.
AB - Noxious cutaneous contact heat stimuli (48 °C) are perceived as increasingly painful when the stimulus duration is extended from 5 to 10 s, reflecting the temporal summation of central neuronal activity mediating heat pain. However, the sensation of increasing heat pain disappears, reaching a plateau as stimulus duration increases from 10 to 20 s. We used functional magnetic resonance imaging (fMRI) in 10 healthy subjects to determine if active central mechanisms could contribute to this psychophysical plateau. During heat pain durations ranging from 5 to 20 s, activation intensities in the bilateral orbitofrontal cortices and the activation volume in the left primary (S1) somatosensory cortex correlated only with perceived stimulus intensity and not with stimulus duration. Activation volumes increased with both stimulus duration and perceived intensity in the left lateral thalamus, posterior insula, inferior parietal cortex, and hippocampus. In contrast, during the psychophysical plateau, both the intensity and volume of thalamic and cortical activations in the right medial thalamus, right posterior insula, and left secondary (S2) somatosensory cortex continued to increase with stimulus duration but not with perceived stimulus intensity. Activation volumes in the left medial and right lateral thalamus, and the bilateral mid-anterior cingulate, left orbitofrontal, and right S2 cortices also increased only with stimulus duration. The increased activity of specific thalamic and cortical structures as stimulus duration, but not perceived intensity, increases is consistent with the recruitment of a thalamocortical mechanism that participates in the modulation of pain-related cortical responses and the temporal summation of heat pain.
KW - Cortex
KW - Functional imaging
KW - Heat pain
KW - Human
KW - Psychophysics
KW - Temporal summation
KW - Thalamus
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U2 - 10.1016/j.pain.2010.04.001
DO - 10.1016/j.pain.2010.04.001
M3 - Article
C2 - 20494516
AN - SCOPUS:77953019741
SN - 0304-3959
VL - 150
SP - 93
EP - 102
JO - Pain
JF - Pain
IS - 1
ER -