Neural mechanisms underlying pain perception and its alteration by conscious state
Bibliographic record
Abstract
Pain perception is highly dependant on the conscious state of the individual and the meaning of the pain. Patients who have pain associated with life-threatening diseases such as cancer may have a heightened state of arousal and focus on their pain, which serves to increase the pain experience. Conversely, professional athletes sustain devastating injuries and continue playing with little or no pain. The studies I have conducted for my Ph.D. have focused on how conscious state alters pain perception, as well as the neural circuitry underlying such modulation. In separate studies, PET and fMRI were used to examine pain perception. The first study examined the cerebral structures necessary for the conscious experience of pain by administering increasing doses of propofol, a non-analgesic anesthetic. Results revealed that at sedative doses, subjects' pain perception was heightened, with associated increased activation in thalamus and cortico-limbic areas. When subjects lost consciousness and stopped responding to the painful stimulus, pain-evoked activation in thalamus and cortical regions (particularly anterior cingulate cortex (ACC)) was dramatically reduced, whereas cerebellar activation remained intact. The second study assessed the effect of hypnotic suggestions to alter the perceived intensity of the sensory-discriminative dimension of the pain experience. Findings revealed that an individual's interpretation of a painful event alters perception, and that the perceptual alteration is subserved by changes in activity in primary somatosensory pathways. The final study investigated the alterations in pain perception in a patient with chronic pain. Data showed that abnormal pain evoked by lightly brushing the skin (allodynia) activated the same cortical neural circuitry as normal pain, demonstrated that whether pain is provoked by normal activation of nociceptive pathways or by central disinhibition of pain pathways through loss of sensory input, there is a signature neural circuitry that corresponds to the conscious appreciation of pain. Together, these studies demonstrate that there is a complex thalamo-cortical neural circuit that is activated during the conscious appreciation of pain, and that activation within this circuit can be modulated by conscious state, resulting in altered pain perception.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".