The effects of contextual conditioning and inhibition of sympathetic activation on pain
Notice bibliographique
Résumé
In a previous pilot study an experimental paradigm in healthy volunteers was developed, which indicated that context conditioning leads to increased anxiety and increased pain sensitivity (i.e. context dependent hyperalgesia). This evidence suggests that the memory for pain influences subsequent pain perception. Additionally, it has been demonstrated that the consolidation of memories for emotionally arousing experiences involves noradrenergic activation of the amygdala. The aim of this study was to investigate how context conditioning and decreased noradrenergic activation affects the perception of pain unpleasantness and intensity in addition to pain tolerance. This double-blind, repeated measures study investigated whether we could obstruct the phenomenon of context-dependent hyperalgesia by using the centrally acting β-adrenergic blocker propranolol to decrease sympathetic activation during the consolidation for pain memories in healthy volunteers. Participants underwent two psychophysical testing sessions and were randomly assigned to the experimental propranolol group (n=20) or the placebo control group (n=21). All subjects filled out the Profile of Mood State questionnaire and underwent the same experimental pain tests in both sessions in order to assess and compare their pain sensitivity. Propranolol or placebo capsules were given to the subjects at the end of the first session. Although we recorded subjects' physiological response to pain, our main outcome measure of interest were unpleasantness and intensity ratings. We hypothesized that decreasing sympathetic activation with propranolol during the conditioning phase would inhibit context-dependent hyperalgesia from occurring. In terms of our outcome measures, we expected unpleasantness and intensity ratings to remain the same or decrease in the propranolol group while the placebo group would return more reactive and rate the pain as more unpleasant and intense.Although our manipulation did not increase feelings of anxiety, control subjects did return more aroused. Furthermore, all subjects were more reactive to painful stimuli on an implicit physiological level despite the fact that context-conditioning did not create context-dependent hyperalgesia. Instead, most pain ratings of intensity and unpleasantness decreased from one session to the next in both groups. Despite the effect of habituation, it is clear that memories of pain and the context in which they were acquired do affect individuals in a psychological and physical manner. We have also demonstrated that modulating the sympathetic tone with propranolol can affect these changes in an experimental setting. Although it might be helpful to be on guard when returning to an environment where you've experienced pain, this experiment highlights that pain memories could be maladaptive by making individuals more sensitive and reactive to future noxious stimuli. In many chronic pain states, it is still unknown how enhanced pain sensitivity is generated and maintained. Perhaps pain memories could be one of the driving forces creating chronic pain.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».