Experimental Brain Research

, Volume 179, Issue 4, pp 655–664

Placebo analgesia: a PET study


    • Department of AnesthesiologyMito Red Cross Hospital
  • Yuki Nemoto
    • Department of AnesthesiologyMito Red Cross Hospital
  • Hikaru Toda
    • Department of AnesthesiologySaitama Cancer Center
  • Masahiko Mikuni
    • Department of Neuropsychiatry and Human BehaviorGunma University
  • Hidenao Fukuyama
    • Human Brain Research CenterKyoto University Graduate School of Medicine
Research Article

DOI: 10.1007/s00221-006-0821-z

Cite this article as:
Nemoto, H., Nemoto, Y., Toda, H. et al. Exp Brain Res (2007) 179: 655. doi:10.1007/s00221-006-0821-z


Placebo analgesia involves complex mechanisms and sometimes has a marked effect on patients in pain. In this study we examined changes in regional cerebral blood flow (rCBF) under three different conditions (resting, hot, painful) before and after placebo administration using H215O and positron emission tomography in ten healthy subjects. In five subjects, placebo administration significantly decreased pain-intensity score (placebo responders), and rCBF in the medial prefrontal cortex (MPFC), posterior parietal cortex (PPC), and inferior parietal lobe (IPL) increased after placebo administration compared with before placebo administration under the painful condition. Furthermore, in the placebo responders, rCBF in the MPFC, PPC and IPL also increased under the resting condition (without sensory stimulation) after placebo administration compared with before placebo administration. However, there was no rCBF change under the rest condition in the placebo nonresponders after placebo administration. These results suggest that placebo analgesia has its effect under the resting condition and MPFC, IPL and PPC may have an important role in placebo analgesia.


Placebo analgesiaPositron emission tomographyRegional cerebral blood flowPsychological effect

Copyright information

© Springer-Verlag 2007