Increased Ongoing EEG alpha power is associated with pain relief in an experimental placebo procedure

AKP Jones, N Huneke, E Burford, A Watson, W El-Deredy

    Research output: Contribution to conferencePoster


    Aim: To identify whether changes in resting Electroencephalogram (EEG) alpha power over the course of an experimental placebo procedure could predict pain reduction in response to a placebo. Method: We used an ethically approved protocol to induce experimental placebo responses using a placebo local anaesthetic cream and experimental pain from a CO2 laser. Healthy volunteers were split into two groups, treatment (HT) and control (HC). The experimental procedure consisted of three periods of repetitive, moderately painful laser stimulation. (1) Pre-conditioning: participants received moderately painful stimuli to the forearms. Following this, an inactive cream was applied to both arms. The HT group were informed that treatment to one arm may contain local anaesthetic. The HC group were informed that the creams possessed no analgesic properties. (2) Conditioning: laser stimuli reduced to non-painful levels on one arm. The HT group were not informed of the reduction in laser energy. (3) Post conditioning: further moderately painful stimuli to both arms. Following each period of laser stimulation, participants rated the pain of each stimulus using a visual analogue scale. Four two-minute resting EEG recordings were taken before, during, and after the procedure. These were analysed through independent component analysis to generate alpha power values over the procedure. Results: Significant changes in the resting EEG were found between recordings in both groups. The HT group experienced significant pain reduction (P = 0.003). Alpha power was significantly increased throughout the procedure in the HT group compared with the HC group (P = 0.015). In addition, the increase in alpha power over the course of the procedure was significantly higher in the HT group than the HC group (P = 0.012). Alpha power in the first EEG recording was significantly correlated with pain reduction in the HT group (P <0.05). Using a stepwise regression model, alpha power in the F4 electrode during the first EEG recording was found to be predictive of pain relief.Conclusions: The differing increase in alpha power over the course of the procedure may reflect the different experiences of each group. The difference seen between the groups at the start of the procedure is likely due to the volunteers’ expectations of pain prior to the start of the experiment. Importantly, alpha power in the F4 electrode is an objective predictor of placebo analgesia and indicates a role for ongoing prefrontal cortical activity in the placebo response.
    Original languageEnglish
    Publication statusPublished - 2012
    EventIASP 2012 - Milan
    Duration: 27 Aug 201231 Aug 2012


    ConferenceIASP 2012


    Dive into the research topics of 'Increased Ongoing EEG alpha power is associated with pain relief in an experimental placebo procedure'. Together they form a unique fingerprint.

    Cite this