What Is the Relationship between Pain and Emotion? Bridging Constructs and Communities

Abstract

Although pain is defined as a sensory and emotional experience, it is traditionally researched and clinically treated separately from emotion. Conceptual and mechanistic relationships between these constructs highlight the need for better understanding of their bi-directional influences and the value of bridging the pain and emotion research and clinical communities.

Keywords: affect; brain; chronic pain; emotion; interoception; mental health; nociception; noxious; pain; subjective experience.

Figure 1.. Pain and Emotion: What Is their Relationship and How Can We Deepen our Understanding Thereof?

(A and B) These panels present four meta-analytic maps generated with Neurosynth (https://www.neurosynth.com), two for the term pain (yellow; 516 studies) and two for the term emotional (red; 1,708 studies). (A) displays voxels that are consistently active in studies that load highly on each of these two terms separately. (B) displays voxels that are more consistently active in studies that load highly on each of the terms separately than for studies that don’t. All maps are corrected at a false discovery rate of 0.01, with voxel intensities binarized. (A) suggests potential overlap between the two terms, as observed in brain regions classically associated with pain, such as anterior and posterior insula, anterior cingulate cortex (ACC), thalamus, and periaqueductal gray (PAG), as well as in brain regions classically associated with emotions, such as the amygdala, ventral striatum, and ventral regions of the medial prefrontal cortex (PFC). (B) suggests potential distinctions between the terms, and, as observed, some of the same regions that previously overlapped, such as the insula, cingulate, and amygdala, now seem to be specific for each of the two terms, and much less overlap is observed. In comprehending these findings, we should note potential limitations for understanding brain processing of pain and emotion—the maps do not distinguish between activations and deactivations, do not provide information about connectivity between brain regions, and are not sensitive to differences between healthy and chronic pain populations. Moreover, experimental paradigms differ between the terms, with emotion inductions mostly using visual stimuli (e.g., faces or scenes), whereas pain inductions commonly requiring physical contact (e.g., thermal or mechanical). This might suggest (B) is more reflective of sensory-specific discrimination. A conceptual consideration of the pain-emotion relationship must therefore complement and guide empirical findings. Coordinates of brain slices are in the Montreal Neurological Institute space. FFG, fusiform gyrus; PAG, periaqueductal gray; PCC, posterior cingulate cortex; SI/SII, primary/secondary somatosensory cortex; SMA, supplementary motor area; A, anterior; P, posterior; L, left; R, right. (C) Using Venn diagrams, this panel presents potential theoretical perspectives regarding the relationship between pain and emotion. Venn1 illustrates the common view of pain as having an emotional component, in addition to sensory and other important components (e.g., cognitive, motivational, socio-cultural). It is thus challenging to conceive of pain and emotion as completely separate phenomena. On the other hand, pain could be conceptualized as a type of emotion category (Venn2), such as fear or anger. Pain could also be conceptualized as a feeling, a more rudimentary neurophysiological element (such as thirst or hunger), though controversy also exists regarding how to differentiate between feelings and emotions, which is beyond our current scope. These two perspectives suggest a vertical relationship between pain and emotion. However, a horizontal relationship between pain and emotion would define them as separate constructs with certain shared and other distinct underlying conceptual and neurophysiological processes (Venn3). Further empirical findings will determine the amount of overlap (as marked by the double-sided arrow), which might even reach complete overlap (Venn4), thereby conceptualizing experiences of pain and emotions as based on the exact same underlying mechanism. (D) Above and beyond theoretical perspectives, we need to deepen and improve our understanding of the bi-directional relationship between pain and emotion at multiple levels of analysis (from the genetic to the socio-cultural) and considering the multiple components (e.g., sensory, motivational, etc.) of the two constructs. This panel highlights several actionable items that will support this process.