In a recent post on invisible neurology, responders still found the whole issue of pain very confusing. There is a lot of subjective control over pain. Researchers are aware by now that what rates as a 10 (excruciating) on the pain scale for one person may rate as only a 2 or 3 (tolerable) for another. It is also known that even when surgical patients are placed under general anesthesia to block pain entirely, under hypnosis these same patients recall that they experienced excruciating pain. So what part of the brain was conscious and what part unconscious from the anesthesia?
All sensation is open to tremendous deviation from person to person, not just pain. To someone who has suffered sexual abuse, a gentle touch can set off alarm and panic (as respondent Scott Masterton noted). Sex itself can be pleasurable, painful, or neutral to the same person at different times. So there is no simple physical explanation, in terms of signals traveling along the nervous system, that will ever comprehend the true nature of even something as basic as pain.
Another respondent, Syamala, who works with computers, suggests that the brain is like hardware that processes software from another source. That source could be mind, soul, the subtle body, or something else. Whatever name it goes by, the software is in control, using the brain for its own purposes. Does this take us a step further in understanding pain?
In one sense it does. Pain isn't a thing, it's an experience. Like all experiences it has two sides, objective and subjective. The objective side (hardware) is shared by most people without variation -- that is, two brains process signals more or less alike. The subjective side (software) is uniquely programmed for each individual. It would appear that there is no need for software to be shared at all. A sado-masochist is free to convert torment into pleasure, a drug addict is free to convert pleasure into torment.
So far, the hardware-software analogy works, but there is a sudden breakdown with the emergence of a mystifying fact: Experience changes the brain. The notion that we all share the same hardware is simply inadequate, for one sees extremely altered brain activity after emotional traumas; different activity between criminals and ordinary people; between people who are more emotional than rational and vice versa. In addition, the billions of dendrites, or nerve branches, connecting each brain cell are totally unique from one person to the next. What makes them take on their unique pattern is experience (and probably genes, also).
So we cannot separate a conscious mind from an unconscious brain. And we cannot give primacy to the physical brain over the non-physical mind. Just as the observer and the observed are intimately related in quantum physics, using your brain makes you both its observer and the thing observed, your mind uses the brain to know itself. A moment of insight, for example, requires the brain to function properly, since insights consist of thoughts, but left to itself, no brain would have any insight -- it would just do what it does, which is electro-chemical processing.
Neurology concerns itself with physical activity. If a person is depressed, it can be shown that too much serotonin is reabsorbed in the synaptic gap, and therefore by inhibiting this "reuptake," the brain can be rebalanced, with the result that the person reports no longer feeling depressed. But it depressed patients can be cued by couch therapy, that is, by talking to them. Experience changes serotonin levels. If you are depressed because you think your girlfriend no longer loves you, hearing her say "I love you" with emotional conviction can cure your depression in an instant.
So, if the mind isn't using the brain, and the brain isn't using itself (a statement most neurologists would disagree with) who is using the brain? The best answer, I think, is "the self." The self is in the brain, outside it, and in between. It is a person but also a process, a history but also in the present (and projecting the future). The self is the same as the experiencer, and once we understand it better, we will know a great deal more about metaphysics and its living connection to the physical world.
In the end, no one is using the brain. The self is interacting with itself, creating experience and then entering into experience to see what it feels like.