Neural and behavioral changes driven by observationally-induced hypoalgesia

Abstract

Observing successful pain treatment in others can induce anticipatory neural processes that, in turn, relieve pain. Previous studies have suggested that social learning and observation influence placebo hypoalgesia. Here, we used electroencephalography (EEG) to determine the neurophysiological changes associated with pain relief acquired through the observation. Thirty-one participants observed a demonstrator undergo painful heat stimulations paired with a “control” cream and non-painful ones paired with a “treatment” cream, which actually were both Vanicreams. After their observation, the participants then received the same creams and stimulations. We found that the treatment cream led to lower self-reported pain intensity ratings than the control cream. Anticipatory treatment cues elicited smaller P2 in electrodes F1, Fz, FC1, and FCz than the control condition. The P2 component localization indicated a higher current density in the right middle frontal gyrus, a region associated with attentional engagement. In placebo responders, the sensorimotor cortex activity captured in electrodes C3, Cz, and C4 indicated that hypoalgesia was positively correlated with resting state peak alpha frequency (PAF). These results suggest that observationally-induced placebo hypoalgesia may be driven by anticipatory mechanisms that modulate frontal attentional processes. Furthermore, resting state PAF could serve as a predictor of observationally-induced hypoalgesia.

Who are the placebo responders? A cross-sectional cohort study for psychological determinants

“…Clinical studies examining placebo responses demonstrate response rates ranging from around 34% 22 for clinical depression to 78% 26 in chronic low back pain. In experimental placebo studies, response rates for placebo range from around 38% 60 to 60% 11 depending on the placebo manipulation. Our findings that TMD participants having similar placebo hypoalgesia compared with HC participants were in line with a meta-analysis comparing placebo analgesia between patients and healthy individual where patients showed slightly greater placebo analgesia than healthy participants.…”

Seeing others is believing – Analgetische Placeboeffekte durch Beobachtungslernen?

“… Live Raghuraman et al. 2019 [ 18 ] Ja Explizite Instruktion 0,64 a 0,36 (klein) Bilder Egorova et al. 2015 [ 11 ] Ja Explizite Instruktion n. a.…”

“…Fast alle Studien, die den Ein- und Ausschlusskriterien entsprachen [ 2 , 9 , 11 , 15 , 18 , 20 , 22 , 24 – 27 ], verwendeten das folgende Modell für das Beobachtungslernen: Die Beobachter:innen sahen in einer Lernphase ein Modell, das nach einem bestimmten Hinweisreiz (Placebo-Cue) einen Schmerzreiz niedriger einstufte als nach einem anderen Hinweisreiz (neutraler Cue). In der Testphase wurden den Beobachter:innen Schmerzreize verabreicht, die sich in der Intensität nicht danach unterschieden, welcher Hinweisreiz dargeboten wurde (siehe Abb.…”

“…Hierbei zeigte sich, dass das Beobachtungslernen einige Tage zuvor einen signifikanten Einfluss auf die Größe eines Placeboeffekts hatte. Von den 12 einbezogenen Studien konnten neun [ 2 , 9 , 11 , 15 , 18 , 20 , 22 , 24 , 25 ] einen signifikanten Placeboeffekt durch das Beobachtungslernen zeigen (siehe Tab. 1 ).…”

Neural Oscillations: Understanding a Neural Code of Pain

“…The human data of gamma oscillations are supported by animal data showing the importance of gamma in pain (Fu and others 2018; Hu and Iannetti 2019; Tan and others 2019; Yue and others 2020). In addition to gamma band activity, alpha band power and recently, peak alpha frequency has been correlated with pain ratings from phasic pain stimuli (Furman and others 2018; Furman and others 2020; Hu and others 2013; Raghuraman and others 2019). Peak alpha frequency in particular has demonstrated promise to be a reliable marker of sensitivity in healthy individuals (Furman and others 2018; Furman and others 2020).…”