Pains that persist long after damaged tissue hasrecovered remain a perplexing phenomenon. Theseso-called chronic pains serve no useful function foran organism and, given its disabling effects, mighteven be considered maladaptive. However, a remarkablesimilarity exists between the neural bases thatunderlie the hallmark symptoms of chronic pain andthose that subserve learning and memory. Bothphenomena, wind-up in the pain literature andlong-term potentiation (LTP) in the learning andmemory literature, are forms of neuroplasticity inwhich increased neural activity leads to a longlasting increase in the excitability (...) of neuronsthrough structural modifications at pre- andpost-synaptic sites. Moreover, the synapticmodifications of wind-up and LTP share a commonmechanism: a glutamate N -methyl-D-aspartate(NMDA) receptor interaction that initiates a calciummediated biochemical cascade that ultimately enhancessignal processing at the -amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptor. This paper arguesthat chronic pain, which has no adaptive value, canbe accounted for in terms of the highly adaptivephenomenon of activity-dependent neural plasticity;hence, some cases of chronic pain can beconceptualized as a memory trace in spinal neurons. (shrink)

This paper discusses recent neuroscientific research that indicates a solution for what we label the ''causal problem'' of pain qualia, the problem of how the brain generates pain qualia. In particular, the data suggest that pain qualia naturally supervene on activity in a specific brain region: the anterior cingulate cortex (ACC). The first section of this paper discusses several philosophical concerns regarding the nature of pain qualia. The second section overviews the current state of knowledge regarding the neuroanatomy and physiology (...) of pain processing. The third section highlights the recent research by Rainville et al. [(1997) Pain affect encoded in human anterior cingulate but not somatosensory cortex, Science, 277, 968-971], which suggests that pain affect is encoded in the ACC. The final section of the paper spells out exactly how these data affect the causal problem of pain qualia. (shrink)

It has been 35 years since the publicationMelzack and Wall's Gate Control Theory whichhypothesized that nociceptive information wassubject to dynamic regulation by mechanismslocated in the spinal cord dorsal horn thatcould ultimately lead to hyperalgesic orhypoalgesic states. This paper examines GateControl Theory in light of our currentunderstanding of the neuroanatomical,neurophysiological and neurochemical substratesof nociception and antinociception. Despiteits initial controversies, no one has proposeda more comprehensive overall theory of painmodulation or has successfully refuted most ofthe basic tenets of this theory.

A widely accepted theory holds that emotional experiences occur mainly in a part of the human brain called the amygdala. A different theory asserts that color sensation is located in a small subpart of the visual cortex called V4. If these theories are correct, or even approximately correct, then they are remarkable advances toward a scientific explanation of human conscious experience. Yet even understanding the claims of such theories—much less evaluating them—raises some puzzles. Conscious experience does not present itself as (...) a brain process. Indeed experience seems entirely unlike neural activity. For example, to some people it seems that an exact physical duplicate of you could have different sensations than you do, or could have no sensations at all. If so, then how is it even possible that sensations could turn out to be brain processes? (shrink)

This paper offers an evolutionary account of chronic pain. Chronic pain is a maladaptive by-product of pain mechanisms and neural plasticity, both of which are highly adaptive. This account shows how evolutionary psychology can be integrated with Flanagan's natural method, and in a way that avoids the usual charges of panglossian adaptationism and an uncritical commitment to a modular picture of the mind. Evolutionary psychology is most promising when it adopts a bottom-up research strategy that focuses on basic affective and (...) motivational systems (as opposed to higher cognitive functions) that are phylogenetically deep. (shrink)