Placebo Effect on Modulating Empathic Pain: Reduced Activation in Posterior Insula.

Yili Zhao,Wencai Zhang,Jianxin Zhang,Jing Luo,Ruixuan Liu

doi:10.3389/fnbeh.2020.00008

Abstract

Little evidence exists to confirm whether the sensory-related neural activity that occurs when observing others in pain is highly responsive to empathy for pain. From a perspective of intervention, the present study employed placebo manipulation with a transferable paradigm to explore whether the sensory regional activation that occurs when viewing pictures of others in pain could be modulated by the placebo effect. We first performed a screening behavioral experiment for selecting placebo responders and then entered them into a functional magnetic resonance (fMRI) experiment in which they were exposed to the same conditions as before. Participants were informed that it was equally possible to be assigned to the treatment group (placebo manipulation) or the no-treatment group (control); they all, in fact, received treatment and placebo effect would be detected by comparing placebo conditions and no-placebo control condition. Each participant experienced a phase of reinforcing placebo belief with pain in self and a phase of testing transferable placebo effect on empathy for pain. As a result, we found significant activation in sensory areas, including the posterior insula (PI) and the postcentral gyrus, and in the middle cingulate cortex while participants observed pictures of others in pain. More importantly, for the first time, we observed relieved activation in the PI modulated by the placebo effect only associated with pain pictures but not with no-pain pictures. This suggests that sensory activity in the PI might be involved in the processing for empathic pain. This new approach sheds light on research and applications in clinical settings.

Highlights

Individual experience tells us that, when seeing others in pain, we seem to understand their situations and share their feelings of pain to some extent
The results demonstrated significantly increased activation with placebo treatment in the subgenual anterior cingulate cortex/orbital frontal cortex (OFC), a region which has been shown to engage in placebo anticipation (Wager et al, 2004), and decreased activation in the amygdala, insula, and dACC when viewing unpleasant pictures (Zhang et al, 2013)
In the behavioral experiment for selecting placebo responders, 24 participants showed a significant placebo effect, in which they reported much higher ratings both on feelings of pain intensity (PI) and on negative emotion induced by seeing others in pain (NE) in the no-placebo control condition than in the placebo condition, t(23) = 5.072, p < 0.001, Cohen’s d = 1.035, 95% confidence interval (CI) for Cohen’s d = (0.529, 1.527), and t(23) = 6.664, p < 0.001, Cohen’s d = 1.360, 95% CI for Cohen’s d = (0.793, 1.912), respectively

Summary

Introduction

Individual experience tells us that, when seeing others in pain, we seem to understand their situations and share their feelings of pain to some extent. In the case of perceiving others’ suffering, the psychoneural resonance in pain-processing areas between other and self may trigger empathic concern, but the same signals may constitute a threat to the individual that can lead to personal distress. This distress can be costly, both physiologically and cognitively, and can eventually conflict with the observer’s capacity to be of assistance to the other, should be alleviated (Decety, 2011)

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Conclusion