This 2016 Israeli human study used whole-head magnetoencephalography (MEG) to study pain perception in military veterans:
“Our findings demonstrate alterations in pain perception following extreme pain exposure, chart the sequence from automatic to evaluative pain processing, and emphasize the importance of considering past experiences in studying the neural response to others’ states.
Differences in brain activation to ‘pain’ and ‘no pain’ in the PCC [posterior cingulate cortex] emerged only among controls. This suggests that prior exposure to extreme pain alters the typical brain response to pain by blurring the distinction between painful and otherwise identical but nonpainful stimuli, and that this blurring of the ‘pain effect’ stems from increased responses to ‘no pain’ rather than from attenuated response to pain.”
- “The pain-exposed participants showed posttraumatic symptoms, which may also be related to the observed alterations in the brain response to pain.
- We did not include pain threshold measurements. However, the participants’ sensitivity to experienced pain may have had an effect on the processing of observed pain.
- The regions of interest for the examination of pain processing in the pain-exposed group were defined on the basis of the results identified in the control group.
- We did not detect pain-related activations in additional regions typically associated with pain perception, such as the anterior insula and ACC. This may be related to differences between the MEG and fMRI neuroimaging approaches.”
The subjects self-administered oxytocin or placebo per the study’s design. However:
“We chose to focus on the placebo condition and to test group differences at baseline only, in light of the recent criticism on underpowered oxytocin administration studies, and thus all following analyses are reported for the placebo condition.”
A few questions:
- If observing others’ pain caused “increased responses to ‘no pain’,” wouldn’t the same effect or more be expected from experiencing one’s own pain?
- If there’s evidence for item 1, then why aren’t “increased responses to ‘no pain'” of affected people overtly evident in everyday life?
- If item 2 is often observed, then what are the neurobiological consequences for affected people’s suppression of “increased responses to ‘no pain’?”
- Along with the effects of item 3, what may be behavioral, emotional, and other evidence of this suppressed pain effect?
- What would it take for affected people to regain a normal processing of others’ “‘pain’ and ‘no pain’?”
https://www.researchgate.net/publication/299546838_Prior_exposure_to_extreme_pain_alters_neural_response_to_pain_in_others “Prior exposure to extreme pain alters neural response to pain in others” Thanks to one of the authors, Ruth Feldman, for providing the full study