Placebo And Opioid Treatment Activate Same Neuronal Network NEW YORK (Reuters Health) Feb 08 Placebo treatment appears to activate the same part of the brain that is activated by opioids, Scandinavian investigators report. Dr. Martin Ingvar, of the Cognitive Neurophysiology Research Group in Stockholm, and colleagues compared regional cerebral blood flow measured by positron emission tomography while inducing pain or a control stimulation in nine subjects. Their findings appear in the February 7th issue of Sciencexpress, the online edition of the journal Science. Pain was induced with a heat stimulation of 48 degrees C during 70 seconds on the dorsum of the left hand. A control condition involved application of a 38 C stimulation. The experiments were repeated three times: no pretreatment; pretreatment with intravenous injection of remifentanil 0.5 g/kg; or pretreatment with saline placebo. In the absence of pretreatment, both stimulations caused increased activity in the contralateral thalamus, bilaterally in the insula, and in the caudal anterior cingulate cortex. The remifentanil activated the rostral anterior cingulate cortex and the lower brainstem, while attenuating the response in the insula. Saline also activated the anterior cingulate cortex "rostral to the anterior cingulate cortex activation during pain" as well as the orbitofrontal cortex. The orbitofrontal area has been implicated in cognitively driven pain modulation, the investigators point out. In addition, they write, "The increased activity in rostral anterior cingulate cortex during [placebo treatment of pain]...may support its involvement in the analgesic response mechanism during placebo." The researchers also noticed an association between opioid activation of the rostral anterior cingulate cortex and adjacent areas and how well subjects respond to placebo treatment. "The experience of pain is always subjective," Dr. Ingvar told Reuters Health. The placebo effect is influenced by several factors, including a person's expectations of the treatment and their desire to feel better, the investigators point out. By showing that placebo and an opioid agonist activate the same brain regions, the findings suggest that some of these same factors may be involved in triggering the pain relief. Despite the evidence that placebo can affect the brain, Dr. Ingvar said that the report "does not support the use of placebo alone in treatment." The findings do show, however, that the placebo effect "is part of every treatment," he said. http://www.sciencexpress.org/ Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.