This 2013 Scandinavian study detailed which brain structures were involved when fooling oneself about actual sensations in favor of expected sensations.
It was hilarious how the researchers used studies of oxytocin to create expectations in the subjects:
“To induce expectation of intranasal oxytocin’s beneficial effects on painful and pleasant touch experience, participants viewed a 6-min locally developed video documentary about oxytocin’s putative prosocial effects such as involvement in bonding, love, grooming, affective touch, and healing. As all of the material was based on published research, there was no deception. The video concluded that a nasal spray of oxytocin might enhance the pleasantness of:
- (i) stroking and
- (ii) warm touch, and
- (iii) reduce the unpleasantness of pain.”
- Only the placebo effects for the warm and pain-reducing touches were statistically significant, not the stroking touch;
- The a priori brain areas monitored in the “sensory circuitry” included the thalamus and were all in the right brain hemisphere;
- The a priori brain areas monitored in the “emotional appraisal circuitry” included the amygdala.
One way the researchers summarized the study was:
“Pain reduction dampened sensory processing in the brain, whereas increased touch pleasantness increased sensory processing.”
I’d say this finding demonstrated how the thalamus part of the limbic system actively controls and gates information to and from the cerebrum, similar to the Thalamus gating and control of the limbic system and cerebrum is a form of memory study.
There was a terminology problem in the study, evidenced by statements such as:
“We induced placebo improvement of both negative and positive feelings (painful and pleasant touch).”
Touch is a sensation, not a feeling or emotion. This placebo study was all about creating expectations of sensations in the subjects’ cerebrums, not creating expectations of emotions.
I’d further note that including parts of the limbic system such as the amygdala in the “emotional appraisal circuitry” didn’t mean that the researchers studied feelings or emotions. We know from research summarized in the Conscious mental states should not be the first-choice explanation of behavior study that:
“Neither amygdala activity nor amygdala-controlled responses are telltale signatures of fearful feelings.“
The current study cast additional light on the dubious Problematic research on human happiness study. I’d say that those researchers were fooled by a positive placebo effect!
http://www.pnas.org/content/110/44/17993.full “Placebo improves pleasure and pain through opposite modulation of sensory processing”