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| Andrea Eugenio Cavanna |
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Department of Neuroscience, University of Turin Medical School Strada Rosero 6 - 10025 Pino Torinese (TO) - ITALY
e-mail: cavanna77@tin.it |
Poster Presentation: |
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| BRAIN MECHANISMS UNDERLYING THE PLACEBO EFFECT: NEW INSIGHTS FROM THE MOTOR DISORDERS. |
| CAVANNA AE, POLLO A, TORRE E, LOPIANO L, RIZZONE M, LANOTTE M, CAVANNA A, BERGAMASCO B, and BENEDETTI F | |
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Department of Neuroscience, University of Turin Medical School |
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| Placebo is a widespread phenomenon in medicine and its neurobiological mechanisms are understood only partially. Most of our understanding of placebo comes from studies on pain. In particolar, placebo analgesia represents a situation where the administration of a substance known to be non-analgesic produces an analgesic response when the subject is told that it is a painkiller. The neurobiology of placebo was born when some authors discovered that placebo analgesia is mediated by the release of endogenous opioids.
Now we know that placebo verbal instructions arise expectations about future events which are known to trigger neural mechanisms affecting not only perception, but also action. Recent neuroimaging studies on Parkinsonian patients who had undergone placebo treatment showed an increase in the endogenous release of dopamine among the basal ganglia circuitry.
Our study tested these findings in the clinical setting of the placebo-induced improvement of the patient’s motor performance. This study reports that different and opposite expectations of bad and good motor performance modulate the therapeutic effects of subthalamic nucleus stimulation in seven Parkinsonian patients who had undergone chronic implantation of electrodes for deep brain stimulation. By analyzing the effects of subthalamic stimulation on the velocity of movement of the right hand, we found hand movement to be faster when the patients expected a good motor performance. The expectation of good performance was induced through a placebo-like procedure, thus indicating that placebo-induced expectations have influence on the treatment outcome. All these effects occurred within minutes, suggesting that expectations induce neural changes very quickly.
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