What is happening in the brain with the 'placebo effect' that improves symptoms with placebo?

In fact calls the fake drugs in which the active ingredient is not included at all and placebo (placebo) looks like a real medicine, improvement in symptoms is seen by drinking the placebo supposed does not contain the active ingredient '

placebo It is said to have an 'effect'. A research team at the University of Sydney School of Medicine has announced an experiment to observe brain activity during this placebo effect.

Brainstem mechanisms of pain modulation: a within-subjects 7T fMRI study of Placebo Analgesic and Nocebo Hyperalgesic Responses | Journal of Neuroscience

Why do placebos work? Scientists identify key brain pathway | Science | AAAS

Placebo Effect Might Not Be All in Your Head

The placebo effect has been known for more than 400 years, and in 1572 there is a record in France that 'some people get the effect just by looking at the drug.' However, it has not been known why patients who are given tablets that are just like sugar can feel reassured. In addition to the placebo effect, there is also a 'nosebo effect' that makes you feel sick or has side effects due to placebo.

To investigate how the placebo or nosebo effect works in the brain, the research team installed a device called a 'thermocord' on the arms of 27 subjects and the temperature at which participants felt pain. It was heated to. After that, the subject was informed that he applied one of 'a cream that relieves pain', 'a cream that induces pain in reverse', and 'a cream that has no effect' to the affected area. However, in reality, all three creams were just petrolatum .

And while the cream was being applied, the team scanned the subject's brain with high-resolution functional magnetic resonance imaging (fMRI) to detect which parts of the brain were most active.

As a result of the experiment, one-third of the subjects who were said to have been applied with painkiller cream 'reduced pain', and more than half of the subjects who were said to have been applied with pain-inducing cream 'increased pain'. I did. '

When the subject's brain was checked at this time, in the subject who said that 'pain was alleviated', the activity of the rostral ventromedular ventromedial part (RVM) that transmits pain information became active, and the peri-water gray matter that suppressed pain sensation. Activity was decreasing. On the other hand, the opposite change occurred in subjects who said that they had 'increased pain.'

It seems to be the opposite of reduced activity in the pain-suppressing area in patients with a placebo effect that reduces pain, but the research team said, 'This finding seems counterintuitive. However, it shows that multiple areas of the brainstem work in a complex way when it comes to producing pain sensations. '

Until now, deep brain stimulation (DBS), which gives electrical stimulation to the brain stem, has been used as a method of relieving pain caused by illness. However, according to Luis Crawford, a neuroscientist at the University of Sydney School of Medicine and lead author of the paper, DBS was unable to pinpoint exactly which part of the brainstem was involved in pain regulation. It seems that it was difficult to get the effect. 'The results of this experiment may lead to treatments for chronic pain in the future,' Crawford said.

'This experiment is wonderful,' said Toll Weiger, a neuroscientist who studies the placebo effect at Dartmouth College. 'There have been studies on the brain response to the placebo and nosebo effects, but this one The case was done with ultra-high resolution fMRI, which revealed the most detailed brain activity to date. '

in Science, Posted by log1i_yk