Does Anticipation of Pain Affect Cortical Nociceptive Systems?

Abstract

Anticipation of pain is a complex state that may influence the perception of subsequent noxious stimuli. We used functional magnetic resonance imaging (fMRI) to study changes of activity of cortical nociceptive networks in healthy volunteers while they expected the somatosensory stimulation of one foot, which might be painful (subcutaneous injection of ascorbic acid) or not. Subjects had no previous experience of the noxious stimulus. Mean fMRI signal intensity increased over baseline values during anticipation and during actual stimulation in the putative foot representation area of the contralateral primary somatosensory cortex (SI). Mean fMRI signals decreased during anticipation in other portions of the contralateral and ipsilateral SI, as well as in the anteroventral cingulate cortex. The activity of cortical clusters whose signal time courses showed positive or negative correlations with the individual psychophysical pain intensity curve was also significantly affected during the waiting period. Positively correlated clusters were found in the contralateral SI and bilaterally in the anterior cingulate, anterior insula, and medial prefrontal cortex. Negatively correlated clusters were found in the anteroventral cingulate bilaterally. In all of these areas, changes during anticipation were of the same sign as those observed during pain but less intense ( approximately 30-40% as large as peak changes during actual noxious stimulation). These results provide evidence for top-down mechanisms, triggered by anticipation, modulating cortical systems involved in sensory and affective components of pain even in the absence of actual noxious input and suggest that the activity of cortical nociceptive networks may be directly influenced by cognitive factors.

Neural components of social evaluation.

“…Structures in the PFC are necessary to learn complex associations and may contribute to awareness of emotional feeling states (Lane et al, 1998). Neuroimaging experiments in which participants are asked to reflectively generate (Teasdale et al, 1999), monitor (Henson, Rugg, Shallice, Josephs, & Dolan, 1999), anticipate (Porro et al, 2002), attribute (Paradiso et al, 1999), or report on (Gusnard, Akbudak, Shulman, & Raichle, 2001) emotional states typically show heightened prefrontal, especially medial prefrontal, activation.…”

Morphological and functional reorganization of rat medial prefrontal cortex in neuropathic pain

“…In humans, different subregions of the PFC have a role in acute pain; the medial prefrontal cortex (mPFC) was found to be involved in signaling the unpleasantness of pain (3); the anterior cingulate cortex mediates the affective component of pain responses (4) and the placebo effect (5); and anticipation of pain is positively correlated with activity in both the anterior cingulate and mPFC (6). Lending support to the hypothesis that chronic pain involves cortical reorganization, functional MRI (fMRI) studies in patients with complex region pain syndrome type I (CRPS-I) and back pain have shown that the patients' real-time rating of perceived intensity of spontaneous pain is associated with novel activity in mPFC (7,8) when compared with activity patterns that correlate with rating of acute pain stimuli.…”

The subjective experience of pain: Where expectations become reality

“…The prefrontal cortex (PFC), anterior insula, and anterior cingulate cortex (ACC) are activated during the anticipation of pain, but their exact role in pain expectation remains poorly delineated (9)(10)(11)(12). Moreover, the neural mechanisms by which conscious predictions about the magnitude of pain influence the experience of pain remain poorly understood and largely unexploited in the treatment of pain.…”