Amygdalar function reflects common individual differences in emotion and pain regulation success

Although the co-occurrence of negative affect and pain is well recognized, the mechanism underlying their association is unclear. To examine whether a common self-regulatory ability impacts the experience of both emotion and pain, we integrated neuroimaging, behavioral, and physiological measures obtained from three assessments separated by substantial temporal intervals. Out results demonstrated that individual differences in emotion regulation ability, as indexed by an objective measure of emotional state, corrugator electromyography, predicted self-reported success while regulating pain. In both emotion and pain paradigms, the amygdala reflected regulatory success. Notably, we found that greater emotion regulation success was associated with greater change of amygdalar activity following pain regulation. Furthermore, individual differences in degree of amygdalar change following emotion regulation were a strong predictor of pain regulation success, as well as of the degree of amygdalar engagement following pain regulation. These findings suggest that common individual differences in emotion and pain regulatory success are reflected in a neural structure known to contribute to appraisal processes

Pain flashbacks in posttraumatic stress disorder

Objectives: Surgical patients who regain consciousness while under general anesthesia may develop symptoms of Posttraumatic Stress Disorder (PTSD). One common PTSD symptom is the experiencing of abnormal perceptions during which the patient feels as if the trauma is recurring. The objective of this report is to document the re-occurrence of pain as part of the PTSD sequelae. Results: We present two patients who developed PTSD following an episode of awareness under anesthesia. In both cases, posttraumatic sequelae persisted for years and included pain symptoms that resembled, in quality and location, pain experienced during surgery. In addition to their similarity to the original pain, these pain symptoms were triggered by stimuli associated with the traumatic situation, suggesting that they were flashbacks to the episode of awareness under anesthesia. Discussion: The similarity between the patients' pain symptoms and pain experienced during trauma, the triggering by traumatic cues, and the associated emotional arousal and avoidance suggest the involvement of a somatosensory memory mechanism

Les facteurs associés au refus de participer à un essai clinique: l’anesthésie péridurale est un élément dissuasif

Purpose To compare patients who participate in a clinical trial for pain management involving epidural anesthesia to those who refuse and document their reasons for refusing. Methods Demographic and health history information was collected from 621 female patients who were screened for inclusion in a pain management trial involving epidural anesthesia. Patients who completed the clinical trial (n = 149) were compared to those who consented to provide screening information but did not enter the trial (n = 472). Results Sixty-seven percent of women who refused cited unwillingness to have an epidural as the reason for their decision. Non-Caucasians (P < 0.01), patients with no history of mood/anxiety disorders (P < 0.0 16) or systemic disease (P < 0.02), and patients with certain types of pain (P < 0.02) were more likely to refuse to participate in the clinical trial. A longer duration between recruitment and surgery was also found to be associated with higher participation rates (P < 0.01). A logistic regression equation significantly predicted which patients would participate or refuse (P < 0.0001), indicating that a specific set of health and demographic factors strongly influence the decision to participate in a trial. Conclusions The decision to participate in a clinical trial is viewed as a risk/benefit analysis. Factors such as short recruitment to surgery intervals and pre-existing pain, which increase the salience of risks associated with the trial, may result in lower participation rates. Overall, epidural anesthesia is a strong deterrent to participation in a clinical trial.Objectif Comparer les patients qui refusent de participer à des essais cliniques sur l’analgésie comportant l’anesthésie péridurale et documenter les raisons de leur refus. Méthode Les données démographiques et médicales ont été recueillies auprès de 621 femmes choisies pour participer à un essai sur le traitement de la douleur comportant l’anesthésie péridurale. Les patientes qui ont participé à l’essai clinique (n = 149) ont été comparées à celles qui ont accepté de fournir les informations nécessaires à la sélection mais qui n’ont pas fait partie de l’étude (n = 472). Résultats Des femmes qui n’ont pas voulu participer à l’essai, 67 % ont justifé leur décision par le refus d’une anesthésie péridurale. Les patientes de race non blanche (P < 0,01), sans antécédents de trouble de l’humeur ou d’anxiété (P < 0,016) ou de maladie systémique (P < 0,02), et celles qui présentaient certains types de douleur (P < 0,02) avaient davantage tendance à refuser de participer. Un plus long intervalle entre le recrutement et l’intervention chirurgicale était aussi associé à un taux plus élevé de participation (P < 0,01). Une équation de régression logistique a permis de prédire de façon signifcative quelles patientes allaient participer ou non (P < 0,0001), indiquant qu’un ensemble spécifique de facteurs médicaux et démographiques influencent fortement la décision. Conclusion La décision de participer à un essai clinique a été considérée comme une analyse risques-avantages. Des facteurs comme un court intervalle entre le recrutement et l’opération et des douleurs préexistantes augmentent les possibilités de risques associés à l’essai et peuvent entraîner de faibles taux de participation. Dans l’ensemble, l’anesthésie péridurale est un élément dissuasif important de participation à un essai clinique.Supported in part by Grant #MOP-37845 from the Canadian Institutes of Health Research (CIHR), Ontario, Canada, a CIHR Investigator Award to Dr. Katz, and Grant #NS35480 from the National Institutes of Health, Bethesda, Maryland

Sound absorption of porous substrates covered by foliage: Experimental results and numerical predictions

The influence of loose plant leaves on the acoustic absorption of a porous substrate is experimentally and numerically studied. Such systems are typical in vegetative walls, where the substrate has strong acoustical absorbing properties. Both experiments in an impedance tube and theoretical predictions show that when a leaf is placed in front of such a porous substrate, its absorption characteristics markedly change (for normal incident sound). Typically, there is an unaffected change in the low frequency absorption coefficient (below 250 Hz), an increase in the middle frequency absorption coefficient (500–2000 Hz) and a decrease in the absorption at higher frequencies. The influence of leaves becomes most pronounced when the substrate has a low mass density. A combination of the Biot's elastic frame porous model, viscous damping in the leaf boundary layers and plate vibration theory is implemented via a finite-difference time-domain model, which is able to predict accurately the absorption spectrum of a leaf above a porous substrate system. The change in the absorption spectrum caused by the leaf vibration can be modeled reasonably well assuming the leaf and porous substrate properties are uniform