Pain
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Empathetic perspective-taking (PT) may be critical in modulating attention and associated responses to another's pain. However, the differential effects of imagining oneself to be in the pain sufferer's situation ("Self-perspective") or imagining the negative impacts on the pain sufferer's experience ("Other-perspective") on attention have not been studied. The effects of observer PT (Self vs Other) and level of facial pain expressiveness (FPE) upon attention to another person's pain was investigated. ⋯ The proportion of total gaze duration on pain faces was higher in both experimental conditions than the Control condition. This effect was moderated by FPE in the Self-PT condition; there was a significant increase from low to high FPE. When observers attend to another's facial display of pain, top-down influences (such as PT) and bottom-up influences (such as sufferer's FPE) interact to control deployment and maintenance of attention.
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Sodium channel Nav1.7, encoded by the SCN9A gene, is a well-validated target that plays a key role in controlling pain sensation. Loss-of-function mutations of Nav1.7 can cause a syndrome of profound congenital insensitivity to pain in humans. Better understanding of how the loss of Nav1.7 leads to loss of pain sensibility would help to decipher the fundamental mechanisms of nociception and inform strategies for development of novel analgesics. ⋯ We observed, however, that after rimonabant administration, Nav1.7 loss-of-function but not WT rats displayed abnormal behaviours, such as enhanced scratching, caudal self-biting, and altered facial expressions; the underlying mechanism is still unclear. Dorsal root ganglion neurons from Nav1.7 loss-of-function rats, although hypoexcitable compared with WT neurons, were still able to generate action potentials in response to noxious heat and capsaicin. Our data indicate that complete loss of dorsal root ganglion neuron excitability is not required for insensitivity to pain and suggest that endogenous opioid and cannabinoid systems are not required for insensitivity to pain in the absence of Nav1.7 channels in this rat Nav1.7 loss-of-function model.
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Meta Analysis
Positive affect and chronic pain: a preregistered systematic review and meta-analysis.
Chronic noncancer pain (CNCP) is a significant health burden among adults. Standard behavioral therapies typically focus on targeting negative affect (NA) and yield only modest treatment effects. The aims of this study were to systematically review and investigate the association between positive affect (PA) and pain severity among adults with CNCP. ⋯ Subgroup analyses showed a significant effect for gender and marginally significant effects for age in studies that adjusted for NA. On average, effect sizes for observational studies were larger in studies with a higher proportion of female respondents and in studies that did not adjust for NA. Finally, larger effect sizes were found in intervention studies with older compared with younger samples.