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Cognitive Science: An Introduction/Psychology of Pain

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The Psychology of Pain

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What is Pain

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Pain can be defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage.[1][2] Pain involves somatosensory, affective, and cognitive features.[3][4] Pain is physiological process in which the experience varies from person to person. It is subjective, experience-based, and is not necessarily caused by direct stimuli. It can be influenced by biological, psychological, and social factors. Pain can be a localized or generalized sensation(s) that cause varying degrees of discomfort and distress.[5] Pain can be acute, occurring suddenly and is often the result of an obvious cause. Traditionally, pain has been viewed mainly as a medical issue that required physical treatment such as medication or surgery. Recent decades have witnessed a growing viewpoint that physical treatments alone can be insufficient and can even worsen the experience of pain. Psychologists applying a biopharmaceutical lens on pain perception has begun shifting to a perspective of pain that integrates its biological, psychological, and social influences.[6][7]

Measuring Pain

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There have been various methods of measuring pain, from nineteenth-century evaluations of cry intensity to more recent observational studies of facial expressions.[8] Since the 1900s doctors have largely relied on a the verbal self-report of pain on a numerical or graphical scale. However, because this pain measurement is variable and subjective it tends to result in under-treatment or over-treatment.[9]

Imaging techniques that have explored the brain’s response to stimulated pain have illuminated the relationship between a person’s perceived pain and how pain is actually registered by the brain.[10] Various techniques are currently used to study pain, including diffusion, structural, and functional magnetic resonance imaging (MRI), electro-encephalography (EEG) and magneto-encephalography (MEG), as well as positron emission tomography. These techniques can measure variation in neurochemical concentrations, electrical activity, blood flow, oxygen metabolism, and other brain activity as it reacts to physical stimuli.[11] It has been argued that brain mapping can provide an overly broad image containing insufficient anatomical nuance. While basic pain signals can appear overly similar, researchers have recently used machine-learning analyses to differentiate pain and its intensity within brain maps.[12][13]  

Emotional Effects

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Pain that has been detected and perceived by the brain is then assigned an emotional value. How pain is emotionally valued can depend upon its cognitive framing, as this can significantly influence pain perception and regulation.[14][15] Pain experienced during exercise, when framed as an indication of progress, can result in positive emotions and the release of analgesic dopamine.[16][17] Emotions can also mitigate the effects of pain as indicated in studies that implicated the role of the insula cortex with the modulation of emotions and pain signals.[18][19]

Pain and Empathy

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An individual’s pain response can also become activated while observing another person’s experience of pain.[20] Research involving fMRI data has indicated that similar neural networks respond in both cases, when a subject directly experienced pain, and when the pain was observed in others.[21][22]  

Placebo Analgesia and Nocebo Effects

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A placebo analgesia involves the expectation that a treatment will inhibit pain and/or provide relief of discomfort. A placebo analgesia is associated with the modulation and activation of brain structures including areas of the frontal cortex, subcortical regions, the insula cortex, and ACC.[23]

The nocebo effect is the opposite of the placebo effect, where an inert treatment is administered while informing the patient that it indicates a worsening condition. Studies have suggested that negative diagnoses and prognoses, mistrust of medical professionals, and negative information in media can lead to an increase in patient pain intensity.[24] 

A meta-analysis indicated that nocebo effects in pain experiences were variable but present. The perception of pain intensity is reportedly higher in those individual who expect an increase in pain compared to those who do not.[25] Similar to placebo analgesia, a patient's expectations can amplify the pain response within the prefrontal cortex, the insula, and the ACC.[26][27]  

The Neuroscience of Pain

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Pain is a result of nerve transmission that communicates the presence of real or potential damage to the brain. By receiving pain signals, humans can respond to real or potential injuries through cognitive, hormonal and motor functions.[28][29]

Nociception

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Nociceptors are peripheral sensory neurons that are activated by a pain stimulus and transmit electrical signals to the brain’s receptors via neurotransmitters. Nociceptors can be excitatory - increasing pain signals, or inhibitory - blocking the transmission of pain signals.[30][31] Nociceptive signals are transmitted via two nervous pathways, the spinothalamic and spinoreticular tracts. The spinothalamic is involved in localizing pain while the spinoreticular is associated with emotional aspects of pain.[32][33] While pain largely involves the conscious awareness of real or potential physical damage, nociception involves the unconscious detection of tissue damage. Nociceptors do not become accustomed to sensations of pain over time and can instead become sensitized under certain conditions.[34]

The Pain Matrix

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Imaging techniques have identified a network of brain structures implicated in the pain response, which has been referred to as the “pain matrix,” or the “neural pain signature.” The primary and secondary somatosensory cortices, as well as the thalamus and cerebellum have been correlated with sensory aspects of pain while the anterior cingulate cortex (ACC), prefrontal cortices, and insular cortex have been connected with with affective and cognitive responses.[35] Further limbic structures are involved in process and are responsible for emotional responses.[36][37] Not all structures in the pain matrix are activated by the pain response, nor to the same extent.[38] Ultimately, there is no core neural structure that is associated with pain perception and processing, rather, it shares commonalities with other sensory, emotional, and stress-related brain regions.[39] The pain matrix is a neurologically complex set of regions controlling ancillary factors and large brain structures that work together. Understanding the role of different areas of the brain in experiencing, perceiving, anticipating, and responding to pain under different conditions provides insight into why people may experience a similar pain differently.[40][41]

A 2014 review found that neural activity in the anterior cingulate cortex (ACC) increased as a result of noxious stimuli, but did not change due to non-noxious stimuli. The research, which studied rodents, found that noxious stimulus caused a change in blood flow in the ACC, and concluded that the ACC was in some way involved in pain processing. The study also found that the ACC contributed to the modulation of pain and pain relief by activating dopamine release signals.[42] The study concluded that subjects who reported greater pain also showed increased pain-related brain activity in brain regions associated with the anticipation or fear.[43]

The insula cortex can also play a role in pain modulation. Its affect on the prefrontal cortex and the ACC under certain conditions suggests that the insula can regulate brain regions responsible for processing somatosensory, affective, and cognitive aspects of pain.[44]

Chronic Pain

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Chronic pain is one that is ongoing and can have causes that are identifiable and non-identifiable.[45] Chronic pain is usually associated with a persistent illness, condition, or long-term injury and varies in severity.[46] While acute pain serves a useful biological imperative that is bounded, chronic pain may serve no function and have no definable end. Additionally, chronic pain can cause further deleterious effects on a person’s quality of life, such as obesity and depression.[47]

Research indicates that the neural mechanisms in the brain stem can raise, stifle, or block pain signals before being received by the brain. In cases of chronic pain, the brain stem can amplify and exacerbates pain signals experienced by a patient.[48] Conversely, this same process can inhibit nociceptive inputs to the brain when a person is distracted or euphoric.[49]

Chronic pain can progressively change physical brain structures and their functionality. Research indicates that the dorsolateral prefrontal lobe can be adversely affected by chronic pain. As this region plays a significant role in various other brain functions such as cognition and emotion, chronic pain can have secondary effects on pain modulation, depression, anxiety, and fear responses.[50]  

The Philosophy of Pain

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Introduction

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The concept of pain has long been studied from various scientific perspectives. Fields of discipline, including psychology, neuroscience, and philosophy, have differing views regarding not only the definition of the term, but what important aspects are involved in researching and studying it as well. The philosophy of pain contrasts views such as the psychological and neuroscientific considerations, and raises several questions surrounding the nature of pain. Philosophers studying pain and its complex components have speculated about various types of pain, whether or not pain should be considered one of humans' basic senses, and the ethical issues that are associated with the condition.

Defining Pain

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Despite the difficulty associated with precisely defining pain, many scientists and researchers concur that pain can be described as “an unpleasant sensory and emotional experience”.[51] In their article, Sytsma and Reuter discuss that several philosophers agree that pain’s existence is dependent upon the experience of an individual.[52] Pain perception is one aspect of the phenomenon that makes it difficult to analyze. Factors such as personality and emotional reactivity are key components that influence the perception that one would have to a certain level of pain.[53] The sensation of pain begins from a specific part of the body and activates the anterior cingulate cortex of the brain, imposing differing reactions to the sensation that is felt depending upon the aforementioned factors.[53] These altering receptions, and the complications that go along with attempting to accurately describe what is being felt, make pain a complicated subject lacking a comprehensive definition.

Various Types of Pain

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Pain can manifest in many different ways, specifically in mental and physical forms, which together have varying impacts on individual perception. Philip R. Appel discusses in his article the idea of the mind-body relationship as it relates to pain, the sensory experience that pain causes, and how this sensory experience can translate into an internal self-conflict.[54] Appel[54] suggests that pain that begins as a physical sensation can develop into a mental challenge in which an individual can be confronted with thoughts such as how vulnerable humans are, and a contemplation of mortality. The mental side of pain becomes prevalent when an individual is faced with an uncomfortable physical sensation, and this pain in turn causes emotional reactions such as sadness or anger. The relationship between physical pain and mental pain has been studied by philosophers, and many believe that pain is a conscious mental state that is achieved once experienced.[52] Based on this research, it is evident that there is a strong correlation between physical and mental pain, and often these sensations coincide to create an individual’s emotional response.

Should Pain be Considered a Sense?

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Many theories contribute to the debate regarding whether pain should be included in the list of a human’s basic senses, along with taste, sight, scent, sound, and touch. As of now, pain is considered to be among a human’s bodily sensations, which include itches and tickles, for example.[55] Because pain can be sensed in different ways, there are legitimate reasons for believing that pain is a physical condition that individuals perceive in areas of the body, as well as reasons for believing that it is not.[55] This controversy has gained particular interest from philosophers who attempt to give a more precise definition of the term, and studying these reasons is beneficial to discovering the most applicable view of pain. Theoretically, several individuals may believe that pain should not be considered as one of human’s basic senses, as its sensation holds a deeper complexity compared to the simple sensation of tasting a specific food item. In contrast, there are schools of thought which hold that pain is experienced similarly to the way that a taste, scent, sound, or touch is experienced, and therefore it should qualify as a basic sense. Regardless of the theories that currently exist for both the inclusion and exclusion of pain as a basic human sense, philosophers continue to study this phenomenon and provide additional reasoning to guide the public in determining whether or not pain should be considered as one of our basic senses.

Ethical Issues Surrounding Pain

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Several ethical issues become prevalent when examining the nature of pain. Philosophers have dedicated time to investigating the different ways that individuals experience and describe pain and have attempted to comprise a definition that encompasses both a physician’s view of pain and a patient’s view of pain. This is to ensure the best possible communication between these individuals. The widely accepted definition of pain that it is an “unpleasant sensory and emotional experience”[51], has provided an acceptable baseline for both patients and clinicians on which to rely. Despite this agreement, there is often some miscommunications when individuals seek to describe their pain, whether physical or mental, to a healthcare provider. As a result of a physician being unable to physically experience the specific pain with which a patient is presenting, it becomes difficult to fully understand and treat the ailment. Often doctors will ask patients to rate their pain on a one to ten scale in an attempt to interpret the intensity and severity of the pain being endured. This assessment poses its own issues, as not every individual will necessarily feel pain the same way, and a low rating given by one patient may be equivalent to a higher rating provided by another patient. This demonstrates the complexity involved in defining pain among healthcare professionals and patients, and the miscommunications that may occur between physicians and patients that can lead to ethical issues. Physician-assisted suicide is a controversial topic that relates to pain and the ethical issues that are included in alleviating pain in end-of-life care.[56] A practitioner whose goal is to diagnose and relieve pain, is faced with the moral and ethical dilemma of helping patients who wish to end their lives as a result of intense or worsening pain. The arguments that are present regarding the ethical and non-ethical natures of physician-assisted suicide are discussions that have been frequently studied and analyzed. This extensive examination of physician-assisted suicide has provided the public with arguments for both the allowance of this practice, as well as reasons for why it should be against the law.

Additional Ethical Issues Associated with the Experience of Pain

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Other ethical issues including unfair treatment as a result of age, gender, or income, for example, are frequently observed in the healthcare field when treating both mental and physical pain.[57] As studied by Powers and Faden, in certain parts of the world, females, dark skinned individuals, and low-income families do not receive the same level of care that additionally privileged individuals receive to manage pain.[58] These disparities have been prevalent for several years and continue to pose questions regarding the ethical issues that are associated with the treatment of pain in the healthcare field.

Conclusion

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The philosophy of pain is a perspective that has been extensively studied and revised in an attempt to give an accurate disciplinary analysis of the concept. The complex nature of pain has encouraged scientists from a variety of fields to consider important aspects of pain, as well as determine helpful theoretical responses to inquiries concerning the topic. Examining scientific arguments including the numerous types of pain, whether or not pain should be considered a basic human sense, and the various ethical issues that are associated with the concept has created a stable foundation backed by successful research that can be further developed by philosophers in the future.

References

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  1. ↑ International Association for the Study of Pain (IASP). (2017, December 14). IASP terminology. IASP. https://www.iasp-pain.org/Education/Content.aspx?ItemNumber=1698
  2. ↑ Bursch, B. (2016). Pain and the Biopsychosocial Model Journal of the AmericanAcademy of Child & Adolescent Psychiatry, 55(10), S34–S34.
  3. ↑ Navratilova, E., Xie, J. Y., Meske, D., Qu, C., Morimura, K., Okun, A., Arakawa, N., Ossipov, M., Fields, H. L., & Porreca, F. (2015). Endogenous opioid activity in the anterior cingulate cortex is required for relief of pain. Journal of Neuroscience, 35(18), 7264–7271
  4. ↑ Roy, M., Piche, M., Chen, J.-I., Peretz, I., & Rainville, P. (2009). Cerebral and spinal modulation of pain by emotions. Nature Precedings. https://doi.org/10.1038/npre.2009.2885.1
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  42. ↑ Navratilova, E., Xie, J. Y., Meske, D., Qu, C., Morimura, K., Okun, A., Arakawa, N., Ossipov, M., Fields, H. L., & Porreca, F. (2015). Endogenous opioid activity in the anterior cingulate cortex is required for relief of pain. Journal of Neuroscience, 35(18), 7264–7271
  43. ↑ Lloyd, D. M., Helbig, T., Findlay, G., Roberts, N., & Nurmikko, T. (2016). Brain areas involved in anticipation of clinically relevant pain in low back pain populations with high levels of pain behavior. The Journal of Pain, 17(5), 577–587. https://doi.org/10.1016/j.jpain.2016.01.470
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  45. ↑ Chapman, C. R. (2020). The neuroscience of pain: Towards objective pain assessment. Retrieved 1 February 2020, from https://www.ncsc.org/~/media/Files/PDF/Conferences%20and%20Events/AAAS/Chapman.ashx
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  50. ↑ Medoff, Z. M., & Colloca, L. (2015). Placebo analgesia: Understanding the mechanisms. Pain Management, 5(2), 89–96. https://doi.org/10.2217/pmt.15
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  52. ↑ a b Sytsma, J., & Reuter, K. (2017, August 28). Experimental Philosophy of Pain. Springer Link.
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  55. ↑ a b Aydede, M. (2019, March 4). Pain. Stanford Encyclopedia of Philosophy.
  56. ↑ Beloucif, S. (n.d.). Pain, Progress and the Suffering of End of Life: Ethical Dilemmas Facing Death.
  57. ↑ Sklar, D. P. (1996). Ethical issues associated with pain research in emergency medicine. Annals of Emergency Medicine, 27(4), 418-420.
  58. ↑ Powers, M., & Faden, R. (2002). Racial and Ethnic Disparities in Health Care: An Ethical Analysis of When and How They Matter. National Academy of Sciences.
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