Re: Explain this brain paradox.

From: Wolf Kirchmeir (wwolfkir_at_sympatico.ca)
Date: 09/27/04 

Date: Mon, 27 Sep 2004 14:55:46 -0400

Sawal_7432 wrote:

>>Migraines and headaches appear to originate in inflammation of the covering
>>of the brain. In migraines there is often abnormal blood flows so the pain
>>may be originating in blood vessels but I suspect it still involves the
>>tissues surrounding the brain. As usual the research is controversial but if
>>you read enough neuroscience you get used to that. Certainty is for the
>>ignorant.
>
>
> Hi again, thanks for the replies to my original question, i think i
> understand what you said.So i would like to make some further pints to
> clarify what i have been told:
> 1)So, a person using drugs, or someone feeling pain in their
> heads, might feel as if the pain's originating from their brains,but
> in actuality the pain is from an area adjacent to the brain,such as
> the membranes surrounding the brain? Does that mean these tissues can
> feel pain? If so, during the preliminary stages of brain sugery,whilst
> the skin around the head and membranes/tissues around the brain are
> being cut,the patient needs anaesthesia administered to him? And once
> the surgeon reaches the brain there is no need for anaesthesia then?

In some cases the surgeon uses local anesthesia only. In these cases,
the patient's responses to mild brain stimulation (via electrodes
administering micro-currents for example) are necessary to help the
surgeon decide where to cut. In other cases, total anesthesia is
administered.

> 2)For the pain to originate in the areas near the brain,but to be
> actually perceived as if coming from the brain is a little odd.For a
> human,the brain is arguably the most vital organ,and yet a person is
> not even able to sense whether the pain of a headache or the euphoria
> from cocaine is from the brain or from the spinal cord or from the
> tissues surrounding the brain.How is it such an incredibly complex
> organ like the brain can mis-interpret the origin of relatively simple
> sensations?

You're assuming that there is a simple pathway between the damaged part
and the brain. There isn't. That's why the treatment of pain is
sometimes very difficult.

Many kinds of pain seem to originate in areas other than the damaged
part. For example, during the onset of a heart attack, the pain usually
seems to be localised in the left arm and shoulder, not in the chest.
That's why people have to be taught to recognise the signs of a heart
attack - they aren't what you would expect if things were as simple as
your last question implies.

Then there's phantom pain: pain perceived in an amputated limb, which
isn't there at all any more.

And chronic pain, a condition that I wouldn't wish on anybody (having
known one sufferer), in which the relationship between the perceived
pain and any inflammation or injury is obscure, to put it mildly, so
that treating the pain is very, very difficult.

> Sorry if my questions seem odd, or as if i'm being too fussy, but i
> just don't understand why the brain can't sense the origin of these
> signals.
> Thanks and bye.

Any one part of the brain can deal only with the signals it actually
gets. These signals are "neural spikes" (electrochemical events in the
nerves) which result in the release of chemicals (neuro-transmitters) at
the synpatic gap (where a nerve touches a neuron), which casues a train
of spikes in the receiving neuron. There's nothing in these spikes to
tell the receiving neurons how many prior neurons were involved in
passing along the information, hence nothing tell where the pain or
whatever originated. They came from the adjacent nerve, is all. So how
do I know that it hurts in my left toe instead of my right one? Because
the signals go other parts of the brain, not just to the bits that
result in "feeling pain." It's not at all simple.

Buried in your puzzlement is a confusion between pain signals and the
experience of pain. They aren't the same thing. Pain signals can be
traced, at least in principle (that doesn't mean all pain signals
pathways are known.) Just how these signals translate into the "feeling
pain" is a mystery - it's part of the mystery of consciousness. What is
known is that anything that blocks or interferes with the pain signal
somewhere along its pathway will reduce or eliminate the experience of
pain. Anesthetics do this by blocking the signals chemically. It's also
possible to use distraction, which presumably blocks the pain signal
somewhere else, but just how is not AFAIK understood. Phantom pain
indicates that pain signals may be generated in the brain itself. Also
keep in mind that pain signals aren't very different from ordinary
sensation signals. For some sensations, perhaps all of them, an increase
in intensity becomes a "feeling of pain." So the problem of perceiving
pain is part of the problem of perceiving anything at all. It's not at
all simple.

PS: Kindly put a space after a period and after a comma.

HTH

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