European journal of pain : EJP
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The aim of the present study was to investigate supraspinal modulation of human lower limb reflex receptive fields (RRFs) on the plantar side of the foot during cognitive tasks either distracting the subjects or actively directing their attention to the electrical stimuli directed to the sole of the foot. ⋯ The size of the RRF area was modulated by the cognitive state demonstrating a link between the cognitive activity and the descending control on spinal withdrawal reflex pathways.
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The daily patient flow at dental emergency departments is subject to fluctuations. The aim of the present study was to investigate whether meteorological parameters were associated with the number of patients reporting acute pain in the oral cavity. ⋯ These findings suggest that changes in barometric pressure were the reason for the observed initiation and/or exacerbation of the various oral pains observed in the emergency room setting. This association has been considered to be rare, with most reports suggesting this phenomenon primarily affects divers and aircraft personnel. Our data suggests otherwise, by providing clear evidence that atmospheric pressure changes commonly influences painful oral conditions.
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Activation of the prefrontal cortex occurs during acute and chronic pain and models of experimental hyperalgesia. The present study was carried out to determine possible miRNA changes in the prefrontal cortex, after inflammatory pain induced by facial carrageenan injection in mice. miRNA microarray analyses showed significantly increased levels of miR-155 and miR-223 in the prefrontal cortex of carrageenan-injected mice. The changes were verified by real-time RT-PCR, and shown to occur bilaterally. ⋯ Significantly downregulated c/ebp Beta but upregulated GCSF, accompanied by increased immunolabeling with an antibody to myeloperoxidase were found in the prefrontal cortex of facial carrageenan treated mice. It is postulated that this could lead to increased inflammation and activation of the prefrontal cortex. Further studies are necessary to determine if specific miRNAs could be useful as therapeutic molecules for pain.
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Pain and the conscious mind (or the self) are experienced in our body. Both are intimately linked to the subjective quality of conscious experience. Here, we used virtual reality technology and visuo-tactile conflicts in healthy subjects to test whether experimentally induced changes of bodily self-consciousness (self-location; self-identification) lead to changes in pain perception. ⋯ This increase was not modulated by the synchrony of stroking as predicted based on earlier work. This differed for self-identification where we found as predicted that synchrony of stroking increased self-identification with the virtual body (but not a control object), and positively correlated with an increase in pain thresholds. We discuss the functional mechanisms of self-identification, self-location, and the visual perception of human bodies with respect to pain perception.
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In anaesthetised rats, systematic electrophysiological recordings from dorsal horn neurones in spinal segments Th13-L5 were made to obtain information about the spinal nociceptive processing from the lumbar thoracolumbar fascia. Six to fourteen percent of the neurones in the spinal segments Th13-L2 had nociceptive input from the thoracolumbar fascia in naïve animals, no neurones responsive to input from the lumbar fascia were found in segments L3-L5. The segmental location of the receptive fields in the fascia was shifted 2-4 segments caudally relative to the spinal segment recorded from. ⋯ The proportion of neurones responsive to input from the thoracolumbar fascia rose significantly from 4% to 15% (P<0.05) in animals with an experimentally-induced inflammation of a low back muscle (multifidus). Moreover, neurones in spinal segment L3 - that did not receive input from the fascia in normal animals - responded to fascia input in animals with inflamed muscle. The data suggest that the nociceptive input from the thoracolumbar fascia contributes to the pain in low back pain patients.