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How the number of learning trials affects placebo and nocebo responses

How the number of learning trials affects placebo and nocebo responses. Luana Colloca , Predrag Petrovic , Tor D. Wager, Martin Ingvar, Fabrizio Benedetti. Terms. Placebo - is a sham or simulated medical intervention that can produce a (perceived or actual) improvement

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How the number of learning trials affects placebo and nocebo responses

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  1. How the number of learning trials affects placebo and nocebo responses LuanaColloca, PredragPetrovic, Tor D. Wager, Martin Ingvar, Fabrizio Benedetti

  2. Terms • Placebo - is a sham or simulated medical intervention that can produce a (perceived or actual) improvement • Nocebo – unpleasant response or reaction caused by a placebo drug or condition.

  3. Review! • http://www.youtube.com/watch?v=n8y04SrkEZU&feature=related

  4. Analgesic Pathway

  5. Placebo analgesia • Some placebo analgesia blocked by naloxone • Placebo affect = opioid modulated pathway • ACC may control placebo response • ACC activity increased by acute pain, opioid analgesia, and placebo analgesia • ACC  PAG

  6. ACC Nociceptive and Analgesic Effects

  7. Expectation and Placebo Analgesia

  8. Expectation and Placebo Analgesia

  9. Factors Influencing Placebo • Cognitive Factors • Expectation of pain relief trigger opioids in CNS • Classical Conditioning • Associations between active analgesics, pain relief, and therapeutic surroundings • Responders and Non-responders

  10. Materials • Electric stimulation to foot • randomized which foot • 100 microseconds • Yellow, green, or red light before shock

  11. Methods • Group 1: one session of conditioning • Group 2: four sessions of conditioning • Both groups: • Non-painful stimuli test • Painful stimuli test

  12. Test Types • Non-painful • Intensity of stimulation above Aβ fiber threshold but below nociceptive Aδ and C fiber threshold • Painful • Above nociceptive Aδ and C fiber threshold levels

  13. VAS Scoring • Subjects scored perception and pain (0-10 VAS) • T and t levels prior to testing • Pain rated after conditioning and test

  14. Testing Procedure

  15. Results (group 1)

  16. Results (group 1)

  17. Results (group 2)

  18. Results (group 2)

  19. Placebo/Nocebo relationship

  20. Placebo/Nocebo relationship

  21. Placebo/Nocebo relationship

  22. Average VAS Response

  23. Results Summery • Short conditioning period • No lasting effects for non-painful condition • Only painful nocebo effect endured • Long conditioning period • Both placebo and nocebo effects endured

  24. Discussion • Conditioning is needed for placebo and nocebo effects • Both conscious and subconscious learning shape behavior • Past experience with pain relief effect the efficacy of treatment • Clinical usage of placebo and avoidance of nocebo

  25. Unrelated… • http://www.youtube.com/watch?v=qIoG4PlEPtY

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