Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Exposure to moderate levels of ultraviolet B radiation (UVB) is painless but nevertheless induces an inflammatory response that sensitizes primary afferent nociceptors. Subsequently, heating the UVB-treated site can sensitize spinal nociceptors. We used a repeated-measures design to determine whether heating the UVB-treated site also triggers ipsilateral inhibitory controls. ⋯ In addition, sensitization to heat induced by the UVB treatment strengthened an ipsilateral anti-nociceptive process elicited by heat-pain. Infrequent but enduring discharge of sensitized primary nociceptive afferents, driven by inflammation after UVB exposure, might initiate a lateralized supra-spinal pro-nociceptive influence that heightens awareness of impending harm on the sensitized side of the body. In addition, a lateralized anti-nociceptive response triggered by an intense barrage of nociceptive signals may help to differentiate stronger from weaker sources of pain.
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Impaired postural control in chronic low back pain (CLBP) has been attributed to deficits in sensory and motor functions. However, it is not known if pain-related anxiety affects motor and cognitive function of postural control. The aim of this study was to compare the interactive effects of postural and cognitive function in CLBP patients with high and low pain-related anxiety and healthy subjects. ⋯ In addition, only the CLBP subjects with high pain-related anxiety showed significantly longer reaction times by increasing the difficulty of standing postural task. Pain-related anxiety may influence the postural cognitive interactions in CLBP patients. Furthermore, it may be considered as a contributing factor for postural strategies adopted by CLBP patients.