The effects of contextual conditioning and inhibition of sympathetic activation on pain
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".