On Thu, Oct 20, 2011 at 2:40 PM, Craig Weinberg <whatsons...@gmail.com> wrote:

>> When I read the newspaper this morning the light
>> has a physical effect on my retina which through a series of complex
>> neural relays modulates the output of the motor neurons to my larynx,
>> tongue and diaphragm producing sound waves relating to what I am
>> reading.
>
> You're inventing a connection where none exists. There is no neural
> pathway for eye-voice coordination. You see through your eyes and you
> speak through your voice. Both processes require that you are
> conscious and voluntarily moving your eyes and larynx. That vocal
> expression has a physical characteristic which we can observe
> externally as motor neuron behaviors.

How do my vocal cords know to produce output relating to the
newspaper? There must be *some* causal chain, otherwise it would be
magic. It would be magic if I could know what is happening on the
other side of the world without a causal link between me and the
event, and it would be magic if I could talk about it without a causal
link between my eyes and my mouth.

>> If any component in this pathway, such as the optic nerve, is
>> replaced with an artificial device that relays the electrical signals
>> in a physiologically appropriate way do you claim that the downstream
>> neurons would respond differently because the artificial nerve lacks
>> the "sense" of the natural nerve?
>
> It depends on the nature of the device and the nature of what it is
> the device replaces. You could replace the retina and your visual
> cortex will learn to use it. If you replace the visual cortex the rest
> of your brain will be able to compensate functionally but you will be
> blindsighted. If you have partial visual cortex replacement your brain
> could adapt and learn to use it.

If the rest of my brain receives the normal electrochemical stimuli
from the replaced part how could it know that anything had changed?
You would have to say that the visual cortex has some non-physical
influence on the rest of the brain, but no such effect has ever been
observed. What has been observed is that neurons fire in response to
the electrochemical signals from the other neurons with which they
interface.

>> If so, then you are claiming that
>> neurons affect other neurons by something other than physical factors,
>> going against not only all of neuroscience but also against all of
>> science.
>
> I forget what number I was on. I'll guess 6.
>
> 6. I have never claimed anything that goes against any neuroscientific
> observation. I repeat again, if you think that I am claiming that,
> then you do not understand what I am saying. My view is more
> scientific because it accounts for all of the phenomena that are
> involved and not just the ones that show up under a microscope.

You are clearly saying just that, since you deny that there is a
physical cause behind the neuron firing. If there is a physical cause
then we can explain why and predict when a neuron will fire; if there
is not we can't. You claim that a neuron can just decide to fire and
go ahead and do it where all the observable physical factors suggest
that it should not. That is contrary to science, by definition.

>> For an artificial neuron I think the timing of the action potential in
>> response to environmental factors is the main thing to get right. I
>> think the neuron's shape is important to take into account in this
>> regard since the shape affects the electric field and excitability,
>> but I don't think its mass is important. But I might be wrong: it
>> could be that neurons sense their neighbours' tiny gravitational field
>> and therefore the network with the artificial neuron would behave
>> slightly erratically until this was taken into account. The
>> engineering project would involve sorting this sort of thing out until
>> eventually the artificial neuron would slot into the network with the
>> level of tolerance that is acceptable for biological neurons.
>
> If the neuron doesn't feel anything, then there is not going to be any
> feeling at the higher processing level. These are living organisms.
> They may not have a level of tolerance that is acceptable, just as
> there is no substitute for water or carbon that is acceptable.

Assume the artificial neuron feels nothing, and all it does it get the
timing right in stimulating neurons to which it interfaces. Could that
still result in those biological neurons firing erratically? How, if
they get the same inputs?

>> Qualia are not observable directly by a third party (you knew this is
>> what I meant).
>
> Why does that matter though? If you connect your brain to theirs then
> you could observe qualia directly, as some conjoined twins do. Why do
> you privilege third party observability when dealing with a first
> person phenomenology?

Because I'm asking what would happen to the qualia if you ignored them
and just took care of the observable behaviour, which must be
explainable in terms of observable causes. If the observable behaviour
were not explainable in terms of observable causes then biologists
would have discovered magic. Magic is where the observable behaviour
is not explainable in terms of observable causes: a table levitating
with no force on it; a neuron firing because the ion channels open
even though the laws of physics demand that they stay closed.

>> What is the mechanism determining the timing of the motor neurons
>> controlling the muscles of speech? Please don't say "the sense of the
>> qualia": what *specifically* at the cellular level causes a particular
>> motor neuron to fire?
>
> The motor neurons each feel that it is time to fire, based upon a
> collective feeling that the organism as a whole is attempting to say
> something. What we think of as the charge and voltage across the cell
> membrane is actually just the physical end of a larger phenomena which
> includes sensorimotive phenomenology. The cell feels something, and
> that feeling looks to us from a great distance like a contraction or
> relaxation of pores, depolarization, action potential, etc. Just as
> the circulation of traffic through a city would look to an alien
> observer like regular patterns of circadian respiration among groups
> of automotive cells.

But what causes a particular ion channel to open, for example? The
purpose of scientific research is to answer this question. The answer
that has been discovered is that some ion channels open when there is
an electric field of sufficient magnitude across them while others
open when a neurotransmitter binds to them. You would say that
somewhere in the brain ion channels open because they feel like it, in
the absence of either the requisite electric field or
neurotransmitter. If that were so then it would have been observed,
overturning all of science.

>> No, no, no. If neurons are coordinated in the spontaneous or even
>> apparently purposeless activity they must have some physical influence
>> on each other, generally thought to be synaptic connections, although
>> there are speculations that the electric field may also be important.
>> Physical influences are observable, understandable scientifically and
>> computable. Henry Markram's group in Switzerland simulating rat cortex
>> observed spontaneous gamma wave-like activity. This wasn't "programmed
>> in", it was emergent behaviour given the basic computational model of
>> the rat neuron when multiple such neurons were connected in a
>> physiological way and the program run on a supercomputer.
>
> The influence that they have on each other has a physical aspect, but
> it has an experiential aspect as well. Sometimes the experiential side
> drives the physical and sometimes it's the reverse. Computational
> models can tell you about the physical aspect, and provide insight in
> how to influence the behavior of neurons and therefore influence the
> nature of the experience, but they can't tell you anything about the
> experience itself and it's influence of intentionality the brain.

You claim the putative non-physical influence is ubiquitous in living
cells, so it would not be unreasonable to expect that it would have
been observed, overturning all of science. But it has never been
observed.

>> But there is a chain of events between telling a person to think of
>> something and the fMRI changes. Even if at some point there is a
>> triggering truly random quantum event there is a causal chain and the
>> quantum event can be modelled probabilistically.
>
> The chain of events has no beginning. It's arbitrary. Your view is
> that everything that happens in the brain can be understood in purely
> neurological terms. Telling a person something requires that the
> patient understands what they said and voluntarily chooses to respond
> by controlling their own low level neurological events. You
> pathologically leave out that detail and try to imply that the high
> level consciousness of the patient is an irrelevant epiphenomenon.

The choosing and understanding, everything to do with consciousness,
cognition and free will, is *as a result of* the mechanistic neural
activity. That is the conventional scientific view.

> By always cherry picking the point at which your chain of causality
> begins, you misdirect your attention to the consequences of the high
> level decisions (the fMRI changes, quantum events, ion channel
> depolarization) rather than the decisions themselves (telling a person
> to think of something, the person choosing to comply, the person
> thinking of something). The decisions have meaning to us regardless of
> the mechanism, whereas the mechanism has no meaning whatsoever outside
> of their relation to our signifying experience. This should be a clue.

The mechanism has no absolute meaning but if it leads to consciousness
it results in meaning in the person thus created.


-- 
Stathis Papaioannou

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