the liver and the brain
Glen M. Sizemore
gmsizemore2 at yahoo.com
Tue Aug 31 20:08:20 EST 2004
DL: Don't you think sleight-of-hand and metaphysics deserves derision?
RS: Well, then let's drop all the sleight-of-hand and metaphysical
prejudices and talk about the brain.
Since the neural net (interneurons) appeared in Cnidaria, what has
changed? For one thing, the DNA has evolved to a point where it is
able to construct a whole series of motor program generators, groups
of neurons that when triggered produce a motor act. These generators
can be modified by experience but they are not learned. We are born
GS: The modification of behavior by experience is the usual definition of
learning. Of course, operant conditioning is defined by a change in
frequency of an originally spontaneous (at the level of behavior) response
(defined by its effect on the environment).
RS: The location in the nervous system of some of these motor program
generators can be more or less specified.
Orofaciopharyngeal movements: facial expression, vocalization,
licking, chewing, and swallowing in the dorsolateral hindbrain.
Reaching, grasping, and manipulating in the spinal cord (cervical
There are more, of course, but we take these for starters.
(The specialist talks about controllers, imitators, motoneuron pools,
The important thing is that these are not, repeat not, learned-they
are constructed by the DNA. Under vocalization are the phonemes-also
provided by the DNA.
GS: I doubt that the last can be backed up. References?
RS: Some synapses in the nervous system can be altered by experience. This
allows us to string the phonemes together into language.
GS: This is a hopelessly sophomoric view of verbal operant behavior. But let
's talk about the simpler behavior - but still operant behavior. Imagine
that we are trying to get a rat to press a lever that requires a force
greater than the rat's own body weight. We could put a rat in an operant
chamber equipped with such a hard-to-operate lever and we would never
witness a movement with a force sufficient to operate such a lever. But let'
s say that we establish lever-pressing as an operant response with a more
normal force requirement. (Incidentally, Ray, how would we do this if the
rat never presses the lever?) Now, we gradually increase the force
requirement. As we do so, the rat's behavior changes topography considerably
until, eventually, the rat is rearing up above the lever and utilizing the
downward momentum of its body to operate the lever. Has learning taken
place? What is the explanatory status of genetics here? If we "get" an
animal to do ANYTHING, NO MATTER WHAT, would we not have to conclude that
that response was consistent, in some sense, with genetics? How could it be
otherwise? That doesn't mean that the genetics are sufficient. You could
observe a million rats for a million years in a million operant chambers
with a million levers requiring a static force higher than the animal's body
weight and never see a single lever press. But I could produce one in a week
or two. Has "learning" taken place, Ray? (I include the scare quotes around
learning for reasons that I won't much go into given your, ummm, limited
ability to profit from what someone smarter than you says. Suffice it to say
that there are certain sorts of variables in the ontogenic history of
animals that can be shown, beyond a shadow of a doubt, to alter behavior -
some of these variables are considered to be the domain of "associative
learning," others the related domain of motivation and emotion, etc.)
RS: This lays the groundwork for a scientific explanation of brain action.
GS: Plus, you ignore the entire issue of functional response classes but,
goddamnit, Ray, you're just too hard to educate.
"ray scanlon" <rscanlon at nycap.rr.com> wrote in message
news:363d693e.0408311503.3f82f3e9 at posting.google.com...
> David Longley writes:
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