Some Things to Look Forward To
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What We May Learn From the Placebo Response

[left brain stuff:]

PLoS Medicine

Barbara Cohen

for the Public Library of Science
Published February 17, 2004

DOI: 10.1371/journal.pbio.0020063
Copyright: © 2004 Public Library of Science. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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February 20, 2004

Scientists See How Placebo Effect Eases Pain

The concept of a placebo effect, by which patients get better from the mere illusion of treatment, has intrigued scientists since it was first proposed in 1955. Since then debate has centered on whether it truly exists and, if it does, how it works. Findings published today in the journal Science offer fresh evidence in support of the existence of a placebo effect, and suggest how a brain influenced by this effect changes its response to pain.

Tor D. Wager of the University of Michigan and his colleagues used functional magnetic resonance imaging (fMRI) to study the brains of volunteers who were exposed to harmless but painful stimuli such as small electric shocks or heat. In some cases, the researchers told participants that a pain-relieving cream had been applied to their skin. When these subjects were shocked, they reported less pain on average than did participants lacking the "anti-pain" cream. Subjects under the influence of the placebo effect also exhibited increased brain activity in an area known as the prefrontal cortex, and decreased activity in well-known pain-sensing regions such as the thalamus, the somatosensory cortex and parts of the cerebral cortex.

The results support the hypothesis that the placebo effect does not interfere with the body's ability to sense pain, but instead affects how the brain modulates its interpretation of the body's signals. Paradoxically, the placebo findings could aid the development of novel therapeutic treatments for pain. Remarks Casey: "One could imagine compounds that would activate these control systems specifically." --Sarah Graham

[right brain stuff:] What I find intriguing about the article on the placebo effect, is that there appears to be a similarity between the way that the brain suppresses pain and the way in which the brain handles traumatic memories.  Another SciAm article, (R. Sapolsky, Sci. Am., Sept 2003 289(3): 87-91 -- not freely avaiable on line)  discusses the current thinking about Posttraumatic Stress Disorder.  Although there has been a lot done with neuroimaging in PTSD, Sapolsky's efforts to intergrate the empirical findings into a coherent therory of pathophysiology are still tentative. Even so, some reasonably solid conclusions can be drawn.  There is a connection between the amygdala and  the prefrontal cortex.   At this point in time, it appears that stress can increase the effect of the amygdala on the prefrontal cortex.  In a person without PTSD, the prefontal cortex can assess the actual threat from a stimulus in the enivorment, and help a person to stay calm if there isn't really anything to be afraid of.  In contrast,  if a person with PTSD is confronted by a reminder of trauma, the amygdala acts upon the prefrontal cortex to prevent the patient from exerting executive control over the response to the reminder.  Thus, the response is based upon emotional associations; the emotional response is resistant to any attempt to suppress it with logic.  As a result, the patient can know -- on an intellectual level --  that there really is nothing to be afraid of, but the knowledge cannot be used to suppress the fear.  Dr. Wagner's finding show that it is possible in some circumstances to enhance the ability of the prefrontal contex to exert executive control over at least one primitive brain response, namely pain.   If it turns out to be possible to use this knowledge to develop better psychological and pharmacological treatments for pain, that would be really cool.  It would very nice icing on an already nice cake if it led to advances in treatment of PTSD as well. 
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