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What constitutes pain?
Available online at www.sciencedirect.com
ScienceDirect Physics of Life Reviews 11 (2014) 553–554 www.elsevier.com/locate/plrev
Comment
What constitutes pain? Comment on “Facing the experience of pain: A neuropsychological perspective” by Franco Fabbro and Cristiano Crescentini Joshua A. Grant Max Planck Institute for Human Cognitive and Brain Sciences, Germany Received 10 June 2014; accepted 10 June 2014 Available online 23 June 2014 Communicated by L. Perlovsky
Keywords: Pain; Emotion; Unpleasantness; Salience; Meditation; Mindfulness
In their thought provoking perspective article, Fabbro and Crescentini [1] review the neuropsychological mechanisms of pain, encompassing physical and psychological pain. An underlying assumption of the article is that experiences, ranging from physical pain to the feelings that accompany thoughts of one’s own death, can all be subsumed under the banner of pain. While Fabbro and Crescentini are certainly not alone in amalgamating these diverse experiences, I would argue that it is not pain that binds them, but rather suffering. I don’t think anyone would argue that burning one’s arm and seeing a loved one burn their arm is different, and feel different, even though both experiences may roughly be categorized as painful. Similarly, being socially excluded or thinking of one’s own death can incite distressful unpleasant feelings. But should these feelings be considered pain? There are several reasons one might include these feelings under the domain of pain. Colloquially the word pain is used to refer to all sorts of disagreeable situations or feelings. Further, the actual definition used by the International Association for the Study of Pain suggests pain has both sensory and affective components and does not require a physical precipitating cause. Thus, one could conclude that the hurt of social exclusion is an instance of the affective component of pain. However, the definition also suggests, to be considered pain, a feeling must have both, a sensory and affective component. While there is potentially a physical sensation associated with exclusion, it bears no resemblance to physical pain. Another point of potential confusion is the affective component of pain itself and how much of that is considered specific to pain. Donald Price has proposed that along with the sensory dimension, physical pain has primary and secondary affective dimensions [2]. The primary affective dimension is stimulus-driven, bottom-up and that which signals alarm. The secondary affect is composed of various independent emotions such as fear that tend to be focused on long term implications of the event. I would argue that what physical pain shares with psychological pain is this secondary affect, making the two phenomena similar but ultimately different. DOI of original article: http://dx.doi.org/10.1016/j.plrev.2013.12.010. http://dx.doi.org/10.1016/j.plrev.2014.06.015 1571-0645/© 2014 Elsevier B.V. All rights reserved.
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J.A. Grant / Physics of Life Reviews 11 (2014) 553–554
In response one could rightly offer up results of research studies showing overlap of brain regions such as the anterior cingulate cortex (ACC) and anterior insula (aINS) for psychological and physical pain systems. However, one must consider that even within the domain of physical pain research there are still many disagreements. Where nociceptive afferent signals actually become the experience of pain is heavily debated, as is the question of whether it is even possible to ‘see’ the neural representation of pain at all [3]. Commonly, activation of ACC/aINS is interpreted as the ‘emotional aspect’ of pain, owing to the fact that activity often correlates with unpleasantness ratings. However, ACC and INS also happen to be nodes of what’s been called the salience network [4], which can be driven, not only by noxious stimulation, but also by non-painful stimuli (e.g. visual or auditory [5]). It is not inconceivable that conditions involving psychological pain would be more salient than the respective control conditions. Taken to extremes one could argue that ALL brain activation typically ascribed to pain, is in fact, salience. This point is not trivial as to study pain one must deliver a stimulus (or ‘painful’ situation), which is perceived as painful, but, probably for evolutionarily adaptive reasons, all painful stimuli (and situations) are salient. References [1] Fabbro F, Crescentini C. Facing the experience of pain: a neuropsychological perspective. Phys Life Rev 2014;11:540–52 [in this issue]. [2] Price DD. Central neural mechanisms that interrelate sensory and affective dimensions of pain. Mol Interv 2002;2:392–403, 339. [3] Iannetti GD, Salomons TV, Moayedi M, Mouraux A, Davis KD. Beyond metaphor: contrasting mechanisms of social and physical pain. Trends Cogn Sci 2013;17:371–8. [4] Seeley WW, Menon V, Schatzberg AF, Keller J, Glover GH, Kenna H, et al. Dissociable intrinsic connectivity networks for salience processing and executive control. J Neurosci 2007;27:2349–56. [5] Downar J, Crawley AP, Mikulis DJ, Davis KD. A multimodal cortical network for the detection of changes in the sensory environment. Nat Neurosci 2000;3:277–83.
ScienceDirect Physics of Life Reviews 11 (2014) 553–554 www.elsevier.com/locate/plrev
Comment
What constitutes pain? Comment on “Facing the experience of pain: A neuropsychological perspective” by Franco Fabbro and Cristiano Crescentini Joshua A. Grant Max Planck Institute for Human Cognitive and Brain Sciences, Germany Received 10 June 2014; accepted 10 June 2014 Available online 23 June 2014 Communicated by L. Perlovsky
Keywords: Pain; Emotion; Unpleasantness; Salience; Meditation; Mindfulness
In their thought provoking perspective article, Fabbro and Crescentini [1] review the neuropsychological mechanisms of pain, encompassing physical and psychological pain. An underlying assumption of the article is that experiences, ranging from physical pain to the feelings that accompany thoughts of one’s own death, can all be subsumed under the banner of pain. While Fabbro and Crescentini are certainly not alone in amalgamating these diverse experiences, I would argue that it is not pain that binds them, but rather suffering. I don’t think anyone would argue that burning one’s arm and seeing a loved one burn their arm is different, and feel different, even though both experiences may roughly be categorized as painful. Similarly, being socially excluded or thinking of one’s own death can incite distressful unpleasant feelings. But should these feelings be considered pain? There are several reasons one might include these feelings under the domain of pain. Colloquially the word pain is used to refer to all sorts of disagreeable situations or feelings. Further, the actual definition used by the International Association for the Study of Pain suggests pain has both sensory and affective components and does not require a physical precipitating cause. Thus, one could conclude that the hurt of social exclusion is an instance of the affective component of pain. However, the definition also suggests, to be considered pain, a feeling must have both, a sensory and affective component. While there is potentially a physical sensation associated with exclusion, it bears no resemblance to physical pain. Another point of potential confusion is the affective component of pain itself and how much of that is considered specific to pain. Donald Price has proposed that along with the sensory dimension, physical pain has primary and secondary affective dimensions [2]. The primary affective dimension is stimulus-driven, bottom-up and that which signals alarm. The secondary affect is composed of various independent emotions such as fear that tend to be focused on long term implications of the event. I would argue that what physical pain shares with psychological pain is this secondary affect, making the two phenomena similar but ultimately different. DOI of original article: http://dx.doi.org/10.1016/j.plrev.2013.12.010. http://dx.doi.org/10.1016/j.plrev.2014.06.015 1571-0645/© 2014 Elsevier B.V. All rights reserved.
554
J.A. Grant / Physics of Life Reviews 11 (2014) 553–554
In response one could rightly offer up results of research studies showing overlap of brain regions such as the anterior cingulate cortex (ACC) and anterior insula (aINS) for psychological and physical pain systems. However, one must consider that even within the domain of physical pain research there are still many disagreements. Where nociceptive afferent signals actually become the experience of pain is heavily debated, as is the question of whether it is even possible to ‘see’ the neural representation of pain at all [3]. Commonly, activation of ACC/aINS is interpreted as the ‘emotional aspect’ of pain, owing to the fact that activity often correlates with unpleasantness ratings. However, ACC and INS also happen to be nodes of what’s been called the salience network [4], which can be driven, not only by noxious stimulation, but also by non-painful stimuli (e.g. visual or auditory [5]). It is not inconceivable that conditions involving psychological pain would be more salient than the respective control conditions. Taken to extremes one could argue that ALL brain activation typically ascribed to pain, is in fact, salience. This point is not trivial as to study pain one must deliver a stimulus (or ‘painful’ situation), which is perceived as painful, but, probably for evolutionarily adaptive reasons, all painful stimuli (and situations) are salient. References [1] Fabbro F, Crescentini C. Facing the experience of pain: a neuropsychological perspective. Phys Life Rev 2014;11:540–52 [in this issue]. [2] Price DD. Central neural mechanisms that interrelate sensory and affective dimensions of pain. Mol Interv 2002;2:392–403, 339. [3] Iannetti GD, Salomons TV, Moayedi M, Mouraux A, Davis KD. Beyond metaphor: contrasting mechanisms of social and physical pain. Trends Cogn Sci 2013;17:371–8. [4] Seeley WW, Menon V, Schatzberg AF, Keller J, Glover GH, Kenna H, et al. Dissociable intrinsic connectivity networks for salience processing and executive control. J Neurosci 2007;27:2349–56. [5] Downar J, Crawley AP, Mikulis DJ, Davis KD. A multimodal cortical network for the detection of changes in the sensory environment. Nat Neurosci 2000;3:277–83.