Re: Fish don't have ethical feet it doesn't mean they can't move- was Re: Ethical feet


"whisky-dave" <whisky-dave@xxxxxxxxxxxxxxx> wrote in message
news:dbliai$a3m$1@xxxxxxxxxxxxxxxxxx
>
> "H Duffy" <Hester_Duffy_nospam@xxxxxxxxxxx> wrote in message
> news:3k4oc5Fsd926U1@xxxxxxxxxxxxxxxxx
>>In either case, I'm not sure what your point is. Yes, the brain is
>>implicated (in humans) in the perception of pain. So what?
> Fish brains and human braiins are very different do not assume they work
> things
> out in the same way.

Actually, no. Some parts of human brains are very different from fish
brains, but the bits of brain that we have in common behave in extremely
similar ways, down to using the same neurotransmitters such as serotonin and
substance P.

>>That doesn't mean that tissue damage isn't _also_ implicated in the
>>perception or transmission of pain, does it?
> Tissue damged goes on throught our lives adn the lives of most living
> creatures
> damaged tissue does not always have to result in pain.

You mean tissue death, which is slightly different. As cells age and die
off, they don't hurt. However, if perfectly healthy tissue (as opposed to
individual cells) is damaged, it almost always _does_ cause pain. There are
a few cases in which it doesn't, with leprosy being the most obvious, but
that's because it kills the nerves first, so when tissue gets damaged,
there's nothing there to transmit the pain.

>> No, it shows that the brain _can_ invent pain. That quite obviously
>> doesn't mean that all pain is invented by the brain, does it?
> Why not.
> If you can stop pain by injecting things while there's still tissue damage
> then you must recognised that tissue damage does not equal pain.

In normal circumstances, it does. Some chemical block pain signals; that
doesn't mean that normally, tissue damage doesn't cause pain; normally,
tissue damage _does_ cause pain.

> Theer's a flat fish that starts life as a normal fish then within a week
> it's eyes
> get moved across it's body and it turns into a flat fish,
> looks pretty painful to me too.
> The way to stop pain is to stop the signals reaching the parts that give
> pain.

Have you ever heard of the spinal cat? It's an experiment which has been
done to investigate pain and where pain is experienced. Basically, what you
do (if you're a qualified neuroscientist; don't do this at home, kids) is
you take an adult cat, and you sever the spinal cord at the base of the
skull in such a way that you don't actually damage anything vital to life;
the cat carries on breathing, its heart still breathes, it can even eat and
drink (although usually such animals are tube-fed). What it can't do is move
voluntarily, or feel physical sensations below the point of severance.
However, if you stab its paw with a pin, it withdraws its paw. Magic, huh?

Well, no, not magic; what this proves is that pain is experienced in the
body, not just the brain, even if it it not experienced consciously (the cat
will show no distress at being stabbed with a pin).

Come to think of it, there was a case of a man who had suffered damage to
the spinal cord after an accident, and was paraplegic; he had no voluntary
control below about the 5th rib, IIRC, and therefore no feeling in his lower
torso and legs, and no bowel or bladder control. In order to help him with
the latter problems, scientists wired him up, in such a way that they could
deliver a small electric shock (which he couldn't consciously feel) to his
thigh, and a large electric shock (which again he couldn't consciously feel)
to his bladder. This latter shock was strong enough to cause his bladder to
contract and thus empty; i.e. when they delivered the strong shock to the
bladder, he peed.
Over a period of days, they would deliver a small shock to his thigh, adn
then immediately afterwards, a strong shock to his bladder, causing him to
pee. Aftter a few days, they no longer needed the strong shock to the
bladder; the small shock to his thigh was enough on its own to trigger his
bladder to empty.
Bear in mind that he was not consciously aware of any sensation either in
his thigh or in his bladder. if the pain was _only_ experienced by his
brain, the shock to his thigh could not possibly have triggered anything in
his bladder.
However, since pain is actually experienced in the non-central nervous
system too, his body was able to learn, without intervention from his brain,
and thus he was able to regain voluntary control over his bladder.

All of which, I daresay, will sail right over your head, Dave, but still,
there we are.

>>If I chop your hand off, it'll hurt, not because the brain is inventing a
>>phantom pain, but because I've just chopped your hand off, causing severe
>>tissue damage and nerve damage.
>
> Not if you used an anthstetic whose job it is not to stop tissue damage
> but to stop the transmission of pain.

That's right, yes; it is possible to interrupt the transmission of pain,
just as it is possible to create pain without tissue damage, but that
doesn't mean that, under normal circumstances, tissue damage doesn't cause
pain.

>
>>>> OK, so for example, Substance P which is implicated in pain
>>>> transmission in humans and other vertebrates; it is also found in some
>>>> fish, suggesting that the neurochemical process of pain transmission is
>>>> occurring.
>>>> http://www.vet.ed.ac.uk/animalwelfare/Fish%20pain/Neurology.htm
>>>> That's the sort of evidence you want?
>>>
>>> That would do
>>
>> So you're satisfied with that?

Could you answer this question, please? You asked for a specific sort of
evidence; I've presented it, you've confirmed that that's the sort of
evidence you wanted. COuld you now confirm that you have taken in this
evidence and that you are now convinced that fish do indeed feel pain?

>> I assume you read the bit further dowen about how that analogy doesn't
>> actually hold up?
>
> But it didn't really make that much sense,

*sigh* yes Dave, it did. What you mean is that you didn't really understand
it.
Can you recognise that those two concepts are different and separate?

no real evidence was shown
> to support that theory of why the anology didn't hold up,

It's an analogy, you moron. You can't show evidence to disprove an analogy,
because it isn't about evidence, it's about analogy.

> maybe you'd care to post that section.

Why? You've read it, haven't you?

>> No I don't. You said that if fish react to damage, their reaction could
>> be caused by distress rather than pain. So could you explain what that
>> means? What is this distress you talk about?
> So why use the term emotional distress it wasn't anything I was planning
> on using
> as evidence either way, because I'm not sure how you'd relate emotions to
> pain
> in humans let alone fish.

You used the term "distress". Could you please explain what you meant by
that term? Don't respond with a question, don't turn it back on me, just
explain to me what _you_ meant when _you_ used the term "distress" to
explain why fish might behave erratically when injured.

H


.

Relevant Pages