From: Rafal Smigrodzki (rms2g@virginia.edu)
Date: Wed Aug 28 2002 - 16:31:53 MDT
gts wrote:
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.
### I talked to my coworker here, who commented that you are making the
basic mistake of an amateur scientist (I'm just quoting him, you know) - you
badly overextend your conclusions beyond the data.
Mouse *behavior* is observed, not subjective experiences, and the
differences between mouse and human brains (notably, the absence of
prefrontal cortex), forbid any extension of data from introspection.
------
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 think that most grant committees would make short work of reviewing
your application, if you include such statements.
--------
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?
### On the contrary, as a professional neurologist I can assure you that
pleasure does have a basis in neurology, specifically, in the brain. And,
of course, I could experience pleasure, even if my brain was floating in
tank with nutrient bath, and some appropriate stimulation - no body needed
to have fun.
------
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. :)
### I would not allow myself the folly of overextending conclusions from
insufficient data. I don't know what alligators feel - I hope you do not
take my intellectual caution as a sign of ignorance.
---------
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.)
### You imply you know more than Ma Evolution - but your hypothesizing is
not supported by data, and you are willfully neglecting a huge amount of
published research. Just go to Medline and run some searches on "Cingulate
Cortex", "Alexithymia", "Brain Injury".
-------
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.
### False. See the above Medline pointers.
--------
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.
### So the experience is not the same, after all? The cortex does make a
difference, right?
That's what I was saying all the time. I'm glad you agree, although it did
take a long time.
-------
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.
### No. You can take a genome and read it using an infinite number of
combinations of proteins, some of them recursively derivable from the
genome, to produce a large, unknown number of different organisms.
If you think cognitive levels are imaginary, try to program your computer by
directly analyzing movements of single electrons - you won't get too far.
---- 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. ### It's me. I like chocolate, have read lots of Lem, etc. etc. - you can define me by exactly describing the wiring pattern of my neurons and the memories and emotions contained within their functionality. No need to mention genes at all, just like a software engineer never needs to know the details of CMOS circuit production. ------- 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. ### They have no life-span because they are not alive. They are bound by the life-spans of the bodies that carry them. Humans will be able to transcend their bodies and leave the genes behind. ----- If our genes could think, they would think "transhumanism." ### If they could think, they wouldn't be genes. They would be people. Rafal
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