The Neurophysiology of the Placebo Response


Leknes was able to locate the sense of anticipation of relief from pain:

Consistent with our prediction that appetitive and avoidance- induced rewards would activate partly the same neural networks, we identified common activation between the two reward tasks in the ventromedial prefrontal (vmPFC) and rostral anterior cingulate (rACC) cortices. This finding extends results from previous studies of monetary tasks where rewards and avoided losses similarly activate ventromedial prefrontal regions. Interestingly, the rostral ACC has been repeatedly implicated in the relief of pain by analgesic drugs, distraction and motor cortex stimulation. This opioid-rich region is also thought to drive placebo analgesia (expectation-induced relief) and has been associated with reward prediction error.

We call this the anticipation of relief from punishment. The so-called placebo response is the result of a normal neurophysiological mechanism. To some extent, the placebo response is a component of every medical intervention.