From: gts (gts@optexinc.com)
Date: Wed Aug 28 2002 - 03:01:37 MDT
My apologies if this is a duplicate message. I received a note from the
server that my original message bounced.
Rafal wrote,
### [The nucleus accumbens] is the seat of reward generation, yes, but
the seat of its experience? Which publications and methodologies can
make this fine distinction?
### We know too little to tell.
We know a great deal, Rafal, though admittedly most of the research is
in lab animals rather than humans. The research involves invasive
procedures to which no sane human would ever consent.
For example if we knock out the gene that encodes for the dopamine (D2)
receptor in mice, those D2 knock-out mice become resistant to the
reinforcing effects of addictive drugs. We can infer from this that
without the dopamine receptor, addictive drugs produce little or no
reward experience. The experience of drug reward is mediated by the
binding of dopamine to its receptors.
Other experiments show the relevant dopamine receptors to be those in
the NAC and other parts of the mesolimbic system.
And still other experiments show that the reward experience from healthy
gene-promoting activities activates the same parts of the brain as that
from addictive drugs.
Taking these three facts together we can be quite confident that the
NAC/mesolimbic system is the seat of the reward *experience*.
Extra dopamine in the nucleus accumbens -> reward *experience*.
I emphasize the word "experience" to make clear that I am referring to
the actual subjective experience of pleasure or satisfaction.
I wonder if you think pleasure and satisfaction have no basis in
neurology. From your writings one could infer that you believe you are a
ghost in the machine, capable in principle of experiencing the rewards
of life sans a physical body. Do you think you are a ghost?
### Have you seen the robots on "Robot Wars"? One could swear they must
experience something, when they smash and cut, otherwise, why would they
bother?
You didn't answer my question. :)
Do you deny that alligators feel some sense of reward when they capture
and devour their prey? In a more general sense, do you deny that
alligators are capable of experiencing emotion? If so then you've never
seen an angry alligator. :)
The point I am making here is that emotional capacity (including the
pleasure of reward) is not wired into the cerebral cortex. Emotions and
pleasure are wired into the midbrain (the reptilian brain).
Higher animals evolved a cerebral cortex to *think*. The circuitry for
emotions was already present in the mesolimbic system. And nature is
seldom redundant. (A cortex with the capacity to experience emotion
separately from the mid-brain would be a waste of valuable resources. It
is much more economical to wire the cortex to the midbrain to connect
thoughts with emotions. And this appears to be what nature has
selected.)
However, I think your robot analogy is not a bad one. If you want to
design a robot that will respond to its environment then you will need
to implement within it some kind of feedback circuitry corresponding to
the biological reward system. If your robot has no capacity to
experience pleasure and satisfaction for acting in appropriate ways then
this is a result of your/our inability to create robots as sophisticated
as those that nature has produced over billions of years of evolution.
> Do you think that reptiles have consciousness (I mean, how could you
> "experience" without being conscious)? I'd rather think their
consciousness
> is of a much lower level than ours, including the absence of
subjective
> experiences subserved by the cortex. We'll know for sure once we
> learn how talk with a forked tongue :-)
Of course reptiles have consciousness! Probably they lack self-awareness
but that is beside the point. The capacity to experience reward is not
contigent upon self-awareness.
I wrote:
Considered alone, the cortex is essentially in
emotionless information processing machine.
### How can you be sure?
People who suffer brain damage in the cortex do not lose their capacity
to experience emotion. Instead they lose their capacity to think and
reason. It follows that the cortex is not the seat of emotions. And as
above, animals with no cortex are quite capable of expressing emotional
behavior.
### You might be going out on a limb here. Having no doubts about the
details of subjective experiences of mice strikes me as rather
overconfident, wouldn't you say?
Not really. However I will rephrase it: I have no doubt that there is no
evidence to suggest that the mouse experiences less happiness upon
learning how to find cheese at the end of the maze than the human feels
upon learning relativity theory. The only real differences are in the
complexities of the respective problems and in the natures of the
respective rewards.
### A gene is a piece of DNA. Within the context of the organism (but
not
alone) it does represent data about chemical reactions needed for
survival. The basic drives, the subjective experiences we have, arise a
couple levels above the genes and it is crucial to maintain a
distinction between the two.
I disagree. The drives are encoded directly into the genes. I think that
to speak of "levels above the genes" is to speak nonsense. Those
supposed additional "levels" to which you refer are themselves products
of gene expression.
It is true that the intercellular chemical processes encoded by the
genes are only the first step in the long and complicated process of
developing organisms with emotions and drives, but you only cloud the
issue by inserting imaginary "levels." The entire process is encoded in
the genes.
There is for example information encoded into your genes the meaning of
which can be translated into English as the instruction "Find and eat
food when energy supply is low." It is because you carry these genes
that you feel a drive to find and eat food when your body indicates that
energy is low. Any organism that carries these genes will experience
subjective thoughts and emotions that correspond to that instruction.
### So you say an organic mind would find it impossible to transfer
his/her personality to an inorganic substrate, dispensing with the
genes?
No, that is not what I say. As I've written, genes are best considered
as *information*. It matters not how that information is recorded. If
necessary it could be recorded on cassette tapes.
##Every time you anthropomorphize a bunch of DNA's, you will have
trouble with defining your own self. You are a slave of the selfish gene
only if you believe in its existence.
Who is this person that you hope to encode into an inorganic substrate?
If he is you, and if you are not a ghost living in a machine, then you
cannot encode yourself into an inorganic substrate without also encoding
the information contained in your genes.
One needn't be embarrassed to be an organic organism defined by genetic
material. We needn't see it as limiting. The desire to exist after the
end of humanity is itself the expression of genes.
Genes exist only to exist. They have no life-span. They are capable of
living forever via replication, and built to do so. They are not bound
by the life-spans of their host organisms or even by the life-spans of
their host species.
If our genes could think, they would think "transhumanism."
-gts
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:16:27 MST