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:dbqt2r$1g5$1@xxxxxxxxxxxxxxxxxx
>
> "H Duffy" <Hester_Duffy_nospam@xxxxxxxxxxx> wrote in message
> news:3k9lhjFt5892U1@xxxxxxxxxxxxxxxxx
>> No, it isn't evidence that amoebas feel pain; they have no nervous
>> systems, and are therefore unable to feel anything.
> But you've claimed that fish rubbing themselves and that fish avoiding
> fire coral
> is evidence of pain

No Dave, i haven't. i've said that rubbing an injury site against something
may be a reaction to pain (as indeed has been shown to be the case), and
that the reaosn why pain is useful is because it encourages animals to avoid
potentially harmful stimuli.

so why not assume amebas moving away from
> irratating chemicals is in response to pain.

Because they don't have a nervous system; without a nervous system, it isn't
meaningful to talk about pain at all. however, we know that fish have a
complex nervous system, and that they have nociceptors, which are nerve
specifically "designed" (for want of a better term) to sense noxious
stimuli; in us and in other vertebrates, nociceptors are what allow us to
feel pain. By analogy, it makes sense that they serve the same purpose in
fish.

>> Could you explain to me what you think pain is, if not a signal
>> transmitted by the nervous system?
> It's a signal, look up at the sky watch a star 'twinkle' it is not a sign
> of pain,
> it is not a sing of communication. The signal we recieve as light is
> interupted
> by solar wid and any other stuff in our atmosphere, it is not a concious
> signal from aliens
> it means nothing.

And now that you've written a nice little poem, could you answer my
question?
What do you think pain actually _is_? Is it a place? A chemical? An emotion?
A colour? What is it?

>> No, not necessarily; local anaesthetics don't get to the brain; they
>> block the signals at the site of origin.
>
> I'm not to sure about that, alcohol affects the brain in such a way as it
> can't
> control movement and sight sometimes hearing too, alcohol doesn't really
> have an adverse effect on your legs but it does make walking more
> difficult
> but it's not the effect of muscles in your leg that make you walk
> irratically it;s the effect the alcohol has on the brain not the legs.
> I've just come back from a lunchtimne drink just to porve it !

Alcohol is not a local anaesthetic, Dave. The fact that some chemicals do
something other than what local anaesthetics do has no bearing whatsoever on
local anaesthetics.

>> Yes, and it can hallucinate images and sounds which don't exist. Does
>> that mean that everything we see is actually only in our heads and not in
>> the real world?
> What is the real world, the colour red is red to us not to everything.

What do you mean by "the colour red is red to us not to everything"?

> And how to you think the we interpret things that do exist.
> Hallucinate images and the like prove that our brain does the
> intepretation
> and not our nerves or any other bodly transducer.

Well, our visual systems are fairly heavily involved, aren't they?

>> Yes; if you stroke the paw, it doesn't withdraw it; it is specifically
>> painful stimuli which get that reaction.
> Try touching the back legs of a cat when it's standing, the front legs
> sometime react the same but to a lesser extent.

But we're not talking about normal cats, Dave. Normal cats certainly have
voluntary reactions and don't like their paws to be touched. Spinal cats
have no voluntary movement below the base of the skull. They can't feel it
when you touch their paws.
Do you understand that?

>
>>> try touching the paw with a feather see if that causes the same pain.
>>
>> it doesn't.
>
> But a cat will mostly move it's paw in response.

But a spinal cat won't, because it is unable to pass messages from its paw
to its brain or from its brain to its paw. Do you understand what a sspinal
cat is, or do you need it explained again?

>> Yes, but that's a voluntary reflex, controlled by the brain. In spinal
>> cats, they don't have any voluntary control over their limbs, because the
>> brain has been disconnected from the body.
>
> A choicken will run around without a head too.

Yes, that's right, for a short while, it will. Whether it will react to
pain, I don't know. If it _does_ react to pain after having its head
removed, what would that tell you?

>> The brain couldn't possibly have learnt to do it, given that his brain,
>> like that of the spinal cat, was no longer properly connected to his
>> lower body; he had no feeling and no voluntary movement.
>
> So it was an automatic movement then rather than a response to pain ?

It was a _learned_ movement, learned apparently without the intervention of
the brain.

> If the subject has no feeling you can hardly claim that it did X or Y
> because of pain.

Unless of course the nerves in his thigh were still responding to the shock
in the same way they would if they were still attached; so for example, if
they were still producing Substance P (which is a "pain" neurotransmitter)
in response to the stimulus, that suggests that the localised area is
"feeling pain", even if the brain is not aware of it.

>> Yes, but the signals in this case came from his thigh, not from his
>> brain.
> Signals don't originate in the brain unless something is wrong.

The signal to empty your bladder usually does come from your brain (informed
by signals from your bladder saying that it's full and needs emptied). In
this case, though, there was no brain/bladder link, and yet the man was able
to control his bladder.

You haven't understood any of this, have you?

>> The point is that, although he was not aware of the sensation of the
>> shock to his thigh, and it didn't register in his brain, it clearly was
>> being registered by his nervous system. Therefore, it cannot be true that
>> pain is processed purely by the brain.
>
> I never said purely, the brain interprets the signals that's what it's
> for.

But those signals can exist and can have an effect even without the brain,
right?

>
>>>> That's right, yes; it is possible to interrupt the transmission of
>>>> pain,
>>> You can't transmit pain, only the signal.
>>
>> The pain is the signal, the signal is the pain.
> No they are not the same thing.

OK: could you please explain to me, clearly and simply, what the differenec
is. No questions, no analogies, no tangents, just tell me what the
difference is between the pain and the signal.

>
>>>> 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.
>>> The association of pain can be because of tissue damage.
>>
>> The association of pain with what?
>
> With what signal the brain has interpeted, it could be pleasure or pain

So you think we just imagine the pain in response to a particular stimulus?

Dave, have you been paying any attention at all to any of the nuerochemical
stuff that has come up in this discussion?

H


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