'Just psychological'?

UNDER THE MICROSCOPE: THE VALUE OF PAINSTAKING RESEARCH

PAIN: A basic fact of life, and usually of death too. It is a phenomenon that we take so much for granted, that it is easy to pass over some of the fascinating clues into the secrets of brain function that it can provide. For example, it is easy to see ourselves as passive recipients to the slings and arrows of the everyday world. In reality, things are very different. Consider the following experiment. "Volunteers" - though it is hard to imagine anyone other than deranged masochists or seriously bankrupt students offering themselves - allowed shocks to be sent through their teeth. The beauty of this approach is that the scientists can quantify the pain felt: the electrical current is increased until the "threshold" is reached when the subject will suddenly declare the procedure to be painful.

Clearly very mad or very impecunious, the subjects were so treated not once, but at several times throughout the day. Amazingly, the pain threshold varied according to the time. The point then is not simply to establish when best to visit the dentist (just after midday as it happens) - but rather to emphasise that the perception of pain is highly variable. The nerves conducting the electrical signals related to pain do not change their properties according to the clock: instead something is happening once those signals arrive in the brain. But what?

There are other examples which show that pain is far from straightforward. Patients on morphine may claim that they still feel the pain, but that it no longer "matters", while studies of schizophrenics have shown that they have a higher pain threshold than comparable "control" groups. And while anticipated pain can be perceived as worse than when it is inflicted out of the blue, there are many anecdotes of soldiers on the battlefield seemingly oblivious to the effects of horrendous injuries.

It strikes me as absurd to dismiss this kind of observation, as some neuroscientists do, as "just psychological". The phrase means nothing, and explains even less. The covert implication is that anything "psychological" is from some airy realm of insubstantial feelings that are in no way rooted in the physical, physiological brain. But just because psychology is concerned more with the personalised brain, it's more macro features and subsequent behaviours, does not mean to say that it can float free of an infrastructure of very real, sludgy grey matter: billions of neurons busily networking with each other.

Rather, the psychological features of pain should help us to understand the physiology. Perhaps the fact that neurons work together in extensive networks could provide a good starting point. After all, pain is often described metaphorically, in terms of something else - pricking, stabbing, burning or excruciating. Following a similar line of thought, it has been suggested that the "phantom limb" pain felt by amputees, could be explained in terms of a group of brain cells working together. This "matrix" of cells allocated to the now absent limb might become over-activated due to the lack of feedback about where the limb was and what it was doing.

Perhaps then the distraction of the battlefield and the exacerbation of anticipation, could be interpreted in terms of the degree of associations operational between neurons at any moment. The greater the networking between neurons, it would follow, the worse the pain. If so then the effects of morphine, the lack of pain in dreams, the raised thresholds of schizophrenics and the biorhythms of midday volunteers, might be explicable in terms of the action of brain chemicals prevailing in variable amounts, that affect how well neurons work together.

Idle speculation on my part maybe, but surely better than writing off an individual's agony as "just psychological". Psychology and physiology are two sides of the same coin: consciousness. The more we can understand how phenomena traditionally regarded as the monopoly of one discipline might actually relate to each other, the more we can design experiments that really do tackle the big questions left to science.