Pain

In this paper we1 assess the potential for research on nonhuman animals to address questions about the phenomenology of painful experiences. Nociception, the basic capacity for sensing noxious stimuli, is widespread in the animal kingdom. Even rel- atively primitive animals such as leeches and sea slugs possess nociceptors, neurons that are functionally specialized for sensing noxious stimuli (Walters 1996). Vertebrate spinal cords play a sophisticated role in processing and modulating nociceptive signals, providing direct control of some motor responses to noxious (...) stimuli, and a basic capacity for Pavlovian and instrumental conditioning (Grau et al. 1990; Grau 2002). Higher brain systems provide additional layers of association, top-down control, and cognition. In humans, at least, these higher brain systems also give rise to the conscious experiences that are characteristic of pain. What can be said about the experiences of other animals who possess nervous systems that are similar but not identical to humans? (shrink)

Which nonhuman animals experience conscious pain?1 This question is central to the debate about animal welfare, as well as being of basic interest to scientists and philosophers of mind. Nociception—the capacity to sense noxious stimuli—is one of the most primitive sensory capacities. Neurons functionally specialized for nociception have been described in invertebrates such as the leech Hirudo medicinalis and the marine snail Aplysia californica (Walters 1996). Is all nociception accompanied by conscious pain, even in relatively primitive animals such as Aplysia, (...) or is it the case, as some philosophers continue to maintain, that conscious experiences are the exclu- sive province of human beings? What philosophical and scientific resources are presently available for assessing claims lying between these extremes? (shrink)

two-dimensional modal framework introduced by Evans [2] and developed by Davies and Humberstone. [3] This framework provides Chalmers with a powerful tool for handling the most serious objection to conceivability arguments for dualism: the problem of..

Functionalism cannot accommodate the possibility of mad pain—pain whose causes and effects diverge from those of the pain causal role. This is because what it is to be in pain according to functionalism is simply to be in a state that occupies the pain role. And the identity theory cannot accommodate the possibility of Martian pain—pain whose physical realization is foot-cavity inflation rather than C-fibre activation (or whatever physiological state occupies the pain-role in normal humans). After all, what it is (...) to be in pain according to the identity theory is to be in whatever state that occupies the pain role for us. (shrink)

(2013). Pain, Chronic Pain, and Sickle Cell Chronic Pain. The American Journal of Bioethics: Vol. 13, No. 4, pp. 14-16. doi: 10.1080/15265161.2013.768859.

Postulating the subcortical organization of human consciousness provides a critical link for the construal of pain in patients with impaired cortical function or cortical immaturity during early development. Practical implications of the centrencephalic proposal include the redefinition of pain, improved pain assessment in nonverbal humans, and benefits of adequate analgesia/anesthesia for these patients, which certainly justify the rigorous scientific efforts required. (Published Online May 1 2007).

According to the increasingly popular perceptual/representational accounts of pain (and other bodily sensations such as itches, tickles, orgasms, etc.), feeling pain in a body region is perceiving a non-mental property or some objective condition of that region, typically equated with some sort of (actual or potential) tissue damage. In what follows I argue that given a natural understanding of what sensory perception requires and how it is integrated with (dedicated) conceptual systems, these accounts are mistaken. I will also examine the (...) relationship between perceptual views and two (weak and strong) forms of representationalism about experience. I will argue that pains pose very serious problems for strong representationalism as well. (shrink)

The ordinary conception of pain has two major threads that are in tension with each other. It is this tension that generates various puzzles in our philosophical understanding of pain. This is a short encyclopedia entry surveying some of the major philosophical puzzles about pain.

What does feeling a sharp pain in one's hand have in common with seeing a red apple on the table? Some say not much, apart from the fact that they are both conscious experiences. To see an object is to perceive an extramental reality -- in this case, a red apple. To feel a pain, by contrast, is to undergo a conscious experience that doesn't necessarily relate the subject to an objective reality. Perceptualists, however, dispute this. They say that both (...) experiences are forms of perception of an objective reality. Feeling a pain in one's hand, according to this view, is perceiving an objective condition of one's hand. Who is closer to truth? Because of such metaphysical issues, the subjectivity of pains combined with their clinical urgency raises methodological problems for pain scientists. How can a subjective phenomenon be studied objectively? What is the role of the first-person method in science? Some suggest that the subjectivity of pains is due to their metaphysical irreducibility to purely physical processes in the nervous system. Can this be true? The study of pain and its puzzles offers opportunities for understanding such larger issues as the place of consciousness in the natural order and the methodology of psychological research. In this book, leading philosophers and scientists offer a wide range of views on how to conceptualize and study pain. The essays include discussions of perceptual and representationalist accounts of pain; the affective-motivational dimension of pain; whether animals feel pain, and how this question can be investigated; how social pain relates to physical pain; whether first-person methods of gathering data can be integrated with standard third-person methods; and other methodological and theoretical issues in the science and philosophy of pain. (shrink)

Consider the following two sentences: " I see a dark discoloration in the back of my hand. I feel a jabbing pain in the back of my hand. " They seem to have the same surface grammar, and thus prima facie invite the same kind of semantic treatment. Even though a reading of ‘see’ in where the verb is not treated as a success verb is not out of the question, it is not the ordinary and natural reading. Note that (...) if I am hallucinating a dark discoloration in the back of my hand, then is simply false. For to be true, therefore, I have to stand in the seeing relation to a dark discoloration in the back of my hand, i.e., to a certain surface region in the back of my hand marked by a darker shade of the usual color of my skin, a certain region that can be seen by others possibly in the same way in which I see it. Also note that although the truth of doesn’t require the possession of any concept by me expressed by the words making up the sentence, my uttering of to make a report typically does — if we take such utterances as expressions of one’s thoughts. So my seeing would typically induce me to identify something in the back of my hand as a dark discoloration. This is a typical case of categorization of something under a concept induced by perception. Of course, my uttering of does more than attributing a physical property to a bodily region, it also reports that I am seeing it. (shrink)

This paper examines pain states (and other intransitive bodily sensations) from the perspective of the problems they pose for pure informational/representational approaches to naturalizing qualia. I start with a comprehensive critical and quasi-historical discussion of so-called Perceptual Theories of Pain (e.g., Armstrong, Pitcher), as these were the natural predecessors of the more modern direct realist views. I describe the theoretical backdrop (indirect realism, sense-data theories) against which the perceptual theories were developed. The conclusion drawn is that pure representationalism about pain (...) in the tradition of direct realist perceptual theories (e.g., Dretske, Tye) leaves out something crucial about the phenomenology of pain experiences, namely, their affective character. I touch upon the role that introspection plays in such representationalist views, and indicate how it contributes to the source of their trouble vis-à-vis bodily sensations. The paper ends by briefly commenting on the relation between the affective/evaluative component of pain and the hedonic valence of emotions. (shrink)

This paper is an attempt to spell out what makes the scientific study of pain so distinctive from a philosophical perspective. Using the IASP definition of ‘pain’ as our guide, we raise a number of questions about the philosophical assumptions underlying the scientific study of pain. We argue that unlike the study of ordinary perception, the study of pain focuses from the very start on the experience itself and its qualities, without making deep assumptions about whether pain experiences are perceptual. (...) This in turn puts scientific explanation in a curious position due to pain’s inherently subjective epistemic nature. The reason for this focus on the experience itself and its qualities, we argue, has to do with pain’s complex phenomenology involving an affective/motivational dimension. We argue for the scientific legitimacy of first‐person phenomenological studies and attempts to correlate phenomenology with neural events. We argue that this methodological procedure is inevitable and has no anti‐physicalist ontological implications when properly understood. We end the paper by commenting on a discussion between two prominent pain scientists in the field, Don Price and Howard Fields, about the need to distinguish more dimensions in the phenomenology of pain and how to classify them vis‐à‐vis the recent scientific findings. Our interest in this discussion is not only to introduce some clarifications but also to show how “neurophenomenology” has already been shaping the scientific research and to back our claim about why this methodology is inevitable with an example. (shrink)

Understanding the nature of pain depends, at least partly, on recognizing its subjectivity (thus, its first-person epistemology). This in turn requires using a first-person experiential method in addition to third-person experimental approaches to study it. This paper is an attempt to spell out what the former approach is and how it can be integrated with the latter. We start our discussion by examining some foundational issues raised by the use of introspection. We argue that such a first-person method in the (...) scientific study of pain (as in the study of any experience) is in fact indispensable by demonstrating that it has in fact been consistently used in conjunction with conventional third-person methodologies, and this for good reasons. We show that, contrary to what appears to be a widespread opinion, there is absolutely no reason to think that the use of such a first-person approach is scientifically and methodologically suspect. We distinguish between two uses of introspective methods in scientific experiments: one draws on the subjects’ introspective reports where any investigator has equal and objective access. The other is where the investigator becomes a subject of his own study and draws on the introspection of his own experiences. We give examples using and/or approximating both strategies that include studies of second pain summation and its relationship to neural activities, and brain imaging- psychophysical studies wherein sensory and affective qualities of pain are correlated with cerebral cortical activity. We explain what we call the experiential or phenomenological approach that has its origins in the work of Price and Barrell (1980). This approach capitalizes on the scientific prospects and benefits of using the introspection of the investigator. We distinguish between its vertical and horizontal applications. Finally, we conclude that integrating such an approach to standard third-person methodologies can only help us in having a fuller understanding of pain and of conscious experience in general. (shrink)

Carruthers claims that (target article,). This may be true in many cases. But like other constructivist claims, it fails to explain occasions when constructed knowledge is accurate, like a well-supported scientific theory. People can know their surrounding world and to some extent themselves. Accurate self-knowledge is firmly established for both somatosensory and social pain.

Dysfunction or injury of pain-transmitting primary afferents' central pathways can result in pain. The organism as a whole responds to such injury and consequently many symptoms of neuropathic pain develop. The nervous system responds to painful events and injury with neuroplasticity. Both peripheral sensitization and central sensitization take place and are mediated by a number of biochemical factors, including genes and receptors. Correction of altered receptors activity is the logical way to intervene therapeutically. [berkley; blumberg et al.; coderre & katz; (...) dickenson; mcmahon; wiesenfeld-hallin et al.]. (shrink)

Complex regional pain syndromes (reflex sympathetic dystrophy, causalgia) are often characterized by pain and autonomic and motor abnormalities. Pathophysiological mechanisms are in the central and peripheral nervous system. Differences in skin temperature and may be used as diagnostic criteria. Sympathetic blocks relieve pain and other symptoms in a subgroup of patients (sympathetically maintained pain, SMP).[blumberg et al.].

Daniel Kahneman and his colleagues have made an interesting discovery about people's preferences. In several experiments, subjects underwent two separate ordeals of pain, identical except that one ended with an added amount of diminishing pain. When asked to evaluate these episodes after experiencing both, subjects generally preferred the longer episode--even though it had a greater objective quantity of pain. These data raise an ethical question about whether to respect such preferences when acting on another's behalf. John Broome thinks that it (...) is wrong to add extra pain in order to satisfy a person's preference for a better ending. His explanation for this intuition is that pain is intrinsically bad. I argue against this explanation, and raise several doubts about the moral intuition Broome endorses. In doing so, I offer alternate interpretations of Kahneman's data, and show that these each yield different values which are relevant to the ethical question. (shrink)

Both the sensory and the motivational-affective component of pain must be taken into account in studies on sex differences as well as on neuropathic, postoperative, sympathetic, and visceral pain. In all these cases, therapeutic strategies should be aimed at controlling the peripheral, central, and psychological mechanisms underlying the global pain experience. Similarly, it should be recalled that some neuropeptides act on both sensory and affective pain mechanisms. [berkley; mcmahon; dickenson; coderre & katz; wiesenfeld-hallin et al.; blumberg et al.].

Sex is one of biology's, that is, life's most potent experimental variables. So, are there sex differences in pain? And are these sex differences applicable clinically? The answer to both questions is decidedly yes, of course. But we still have a long way to go. We have much to learn from the study of females, making use of the lifelong changes in their reproductive conditions as experimental variables. We also have much to learn from animals, especially if we apply what (...) we know about their social lives. However, the challenge in all of these studies is not first to look for some mythical neurological entity called pain experience and then to learn how sex modulates it, but rather to seek to understand the rules by which sex influences all of biology's mutually modulatory factors that collectively create the motivating circumstances we designate as pain. It appears almost beyond doubt that on the one hand these factors interact to make women more vulnerable to these circumstances than men, but on the other hand that women have more varied mechanisms for balance. Happily, the details of these sex differences at all levels biological (social to genetic) are now emerging in a rapidly growing body of literature that promises new insights into and applications for the individual person, male or female, in persistent pain. (shrink)

Are there sex differences in pain? For experimentally delivered somatic stimuli, females have lower thresholds, greater ability to discriminate, higher pain ratings, and less tolerance of noxious stimuli than males. These differences, however, are small, exist only for certain forms of stimulation and are affected by many situational variables such as presence of disease, experimental setting, and even nutritive status. For endogenous pains, women report more multiple pains in more body regions than men. With no obvious underlying rationale, some painful (...) diseases are more prevalent among females, others among males and, for many diseases, symptoms differ between females and males. Sex differences in attitudes exist that affect not only reporting, coping, and responses to treatment, but also measurement and treatment. So many variables are operative, however, that the most striking feature of sex differences in reported pain experience is the apparent overall lack of them. On the other hand, deduction from known biological sex differences suggests that these are powerful sex differences in the operation of pain mechanisms. First, the vaginal canal provides an additional route in women for internal trauma and invasion by pathological agents that puts them at greater risk for developing hyperalgesia in multiple body regions. Second, sex differences in temporal patterns are likely to give rise to sex differences in how pain is and stimuli are interpreted, a situation that could lead to a greater variability and wider range of pains without obvious peripheral pathology among females. Third, sex differences in the actions of sex hormones suggest pain-relevant differences in the operation of many neuroactive agents, opiate and nonopiate systems, nerve growth factor, and the sympathetic system. Thus, while inductive analysis of existing data demonstrate more similarities than differences in pain experience between females and males, deductive analysis suggests important operational sex differences in its production. (shrink)

The persistence of both inflammatory and neuropathic pain can only be explained when learning processes are taken into account in addition to sensitizing mechanisms. Learning processes such as classical and operant conditioning create memories for pain that are based on altered synaptic connections in supraspinal structures and persist without peripheral input. [coderre & katz; dickenson; wiesenfeld-hallin et al.].

The most cursory examination of the history of artificial intelligence highlights numerous egregious claims of its researchers, especially in relation to a populist form of ‘strong’ computationalism which holds that any suitably programmed computer instantiates genuine conscious mental states purely in virtue of carrying out a specific series of computations. The argument presented herein is a simple development of that originally presented in Putnam’s (Representation & Reality, Bradford Books, Cambridge in 1988 ) monograph, “Representation & Reality”, which if correct, has (...) important implications for turing machine functionalism and the prospect of ‘conscious’ machines. In the paper, instead of seeking to develop Putnam’s claim that, “everything implements every finite state automata”, I will try to establish the weaker result that, “everything implements the specific machine Q on a particular input set ( x )”. Then, equating Q ( x ) to any putative AI program, I will show that conceding the ‘strong AI’ thesis for Q (crediting it with mental states and consciousness) opens the door to a vicious form of panpsychism whereby all open systems, (e.g. grass, rocks etc.), must instantiate conscious experience and hence that disembodied minds lurk everywhere. (shrink)

Certain patients with a possible contribution of the sympathetic system to pain may not fit the definition of complex regional pain syndromes (CRPS), which raises the question of terminology for those patients. To further clarify the relationship between the sympathetic system and pain, apart from the need for placebo studies, there remains an urgent need for a satisfactory definition of the criteria for a complete sympathetic block. It also remains uncertain whether a change in the discharge pattern of sympathetic fibres (...) underlies the changes in sympathetic organ function, often found in patients with CRPS. (shrink)

The target article discusses various aspects of the relationship between the sympathetic system and pain. To this end, the patients under study are divided into three groups. In the first group, called (RSD), the syndrome can be characterized by a triad of autonomic, motor, and sensory symptoms, which occur in a distally generalized distribution. The pain is typically felt deeply and diffusely, has an orthostatic component, and is suppressed by the ischemia test. Under those circumstances, the pain is likely to (...) respond to sympatholytic interventions. In a second group, called (SMP) syndrome, the principal symptoms are spontaneous pain, which is felt superficially and has no orthostatic component, and allodynia. These symptoms, typically confined to the zone of a lesioned nerve, may also be relieved by sympathetic blocks. Since the characteristics of the pain differ between RSD and SMP, the underlying kind of sympathetic–sensory coupling may also vary between these cases. A very small third group of patients exhibits symptoms of both RSD and SMP. The dependence or independence of pain on sympathetic function reported in most published studies seems to be questionable because the degree of technical success of the block remains uncertain. Therefore, pain should not be reported as sympathetic function independent until the criteria for a complete sympathetic block have been established and satisfied. (shrink)

According to recent evidence, neurophysiological processes coupled to pain are closely related to the mechanisms of consciousness. This evidence is in accordance with findings that changes in states of consciousness during hypnosis or traumatic dissociation strongly affect conscious perception and experience of pain, and markedly influence brain functions. Past research indicates that painful experience may induce dissociated state and information about the experience may be stored or processed unconsciously. Reported findings suggest common neurophysiological mechanisms of pain and dissociation and point (...) to a hypothesis of dissociation as a defense mechanism against psychological and physical pain that substantially influences functions of consciousness. The hypothesis is also supported by findings that information can be represented in the mind/brain without the subject’s awareness. The findings of unconsciously present information suggest possible binding between conscious contents and self-functions that constitute self-representational dimensions of consciousness. The self-representation means that certain inner states of own body are interpreted as mental and somatic identity, while other bodily signals, currently not accessible to the dominant interpreter’s access are dissociated and may be defined as subliminal self-representations. In conclusion, the neurophysiological aspects of consciousness and its integrative role in the therapy of painful traumatic memories are discussed. (shrink)