Believe It Or Not, Placebos And Pain Control

Placebos and pain control do not have a clear mechanism. Neuroimaging has shown that the belief in that the magic pill reduces activity in the various parts of the brain called the “pain matrix”. What doesn’t appear quite so straightforward is that a couple of other parts of the brain show increased activity, that is the medial and lateral prefrontal cortex light up.

This intrigued Koban et al who postulated that decision were being made that there were errors in the signals that the brain was processing (1). They decided on a series of experiments with 18 undergrads from Ghent who were fed a story that their brain activity was being measured to determine the effects of a regular painkiller on their ability to work an attention task on the computer.

Some had the placebo and the control group was told that the pill was a sugar pill and they were the control. So far, so good, but they were dealing with a so-called painkiller so pain had to be introduced. This was in the form of a heated pad on their arm. They had to indicate the intensity of the pain so the “effect” of the painkiller could be monitored.

Errors in the attention task showed up as potential changes in the EEG measurements. A negative potential spike occurred as an error was being made and this was followed by a positive potential spike a fifth of a second later as the awareness of the error was being processed.

Although there was no placebo effect on the negative potential, there was an increase in the positive potential spike with those making an error who had the placebo, suggesting that the cognitive circuits were working harder at processing the error in incoming signal compared to the perception of what it should be – they were doing their best at a cover-up.

So it seems that placebos work by both turning down the pain monitoring activity, but in addition increase the error handling to confirm the misrepresentation.

I wonder if our brains respond in the same manner when we are told that the new austerity measures won’t really be as painful as we think.


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