Symposium on pain

As pain is a sensation generated in the brain, the validity of the distinction that is often made between physical and psychic pain can be questioned. We postulate that the distinction is irrelevant for the person experiencing pain or grief. Both physical and psychic pain, as well as other causes, can lead to mental suffering. The medical profession, and society in general, take psychic pain and mental suffering much less seriously than physical pain. We discuss existential depression, which affects the stability and integrity of the entire personality, and argue for a more prominent place of psychic pain and mental suffering in medical and bio-ethical discourses.

Pain is a subjective phenomenon with those characteristics that typify the mind: experience of the self representation, time integration, intentionality. Without consciousness there is no pain. Although pain is usually felt at the site of injury, the anatomical substrate of pain experience is the brain. Representational and psychic states are attributed to cortical activity as evidenced by novel functional brain imaging techniques. The sensory discriminative component of pain is assigned to bilateral activity in secondary somatosensory cortex areas (SII) with somatotopy and stimulus-response functions. Under narcosis, the cortex cannot explore the kind, size or site of the hurting event as SII activity is blocked. Consequently, pain is not felt. The nociceptive impact induced during surgery, however, may still reach pain-relevant structures in the brain, eliciting nocifensive responses, motor withdrawal reflexes and changes in blood pressure and circulation, and heart action. The emotional-aversive component is very important for the perception of pain. It describes its negative quality, and is attributed to the posterior cingulated cortex. Intimate fibre connections link the relevant neuronal assemblies with the parietal lobe and other structures which evaluate the adversity of the stimulus. Opiates drastically reduce activity in precisely these areas.

This paper defends against objections the widely accepted truism that pain is bad and therefore should be avoided or minimized. This truism seems to be in conflict with our attitudes towards, and treatment of, non-human animals. It may therefore have sweeping implications regarding our treatment of them.

Pain is an aversive sensation and feeling associated with actual or potential tissue damage. A pain system involving receptors, neural pathways and analytical centres in the brain exists in many kinds of animals. Feelings of pain in many species are indicated by physiological responses, direct behavioural responses and ability to learn from such experiences so that they are minimised or avoided in future. Species differ in their responses to painful stimuli because different responses are adaptive in different species but the feeling of pain is probably much less variable. In early evolution, pain must have involved cell sensitivity and localised responses but efficacy would have improved with efficient communication within the individual and sophisticated brain analysis. Pain systems have probably changed rather little during vertebrate evolution. Pain may be a greater problem for animals with less cognitive ability. The distinction between pain and nociception does not seem to be useful.