In article <MASTRD-250494002908 at 18.104.22.168>,
MASTRD at ctrvax.Vanderbilt.edu (Russell Mast) wrote:
> Just had to add one more thing. When your dog spins in circles to mat down
> prarie grass, I really don't think s/he is "remembering" anything, nor
> would s/he think about grass, matting, or praries.
>> Much more likely, it's just some strange obsession with the animal, some
> kind of drive, a discomfort that comes from not having spun around. And
> that's pretty easy to enforce with non-junk DNA. A lot of animals come
> with what are called 'motor programs', stereotyped sequences of actions
> that can be done as effortlessly as a single activity. (Why do you suppose
> your arms swing when you walk, and why does their synchornoization with
> your legs change with your speed?) Anyway, just hook up the motor program
> for sitting down with a specially-designed one about spinning around. Make
> the pup feel funny for not doing one before the other with some
> limbic-extrapyramidal hookups, and, viola', you have a beast that is really
> uncomfortable about lying down without spinning in circles.
Saying there is a "motor program" for something like spinning is no more
useful than saying there is junk-DNA for it, I would hazard. One is led
to ask, "where is this motor program stored?" and "how is it switched on?"
and other sorts of questions that fit in with this computer-based metaphor.
Now it is true that many animals have stereotypical behaviors. Complex
patterns like this can be produced by relatively simple, repetitive actions,
such as in nest building or web spinning. There need not be any program
for web spinning at all, merely a small set of other behaviors.
Synchronization of your arms and legs while you walk is probably not the
result of a "motor program." It is a natural consequence of any coupled
oscillator system that synchronization occurs. This is another example of
pattern formation in complex systems. Simple behaviors (oscillators) create
complex, higher-level patterns (coordination of arms and legs).
Similarly for spinning. No specific "program" need specify how arms and legs
must be positioned for spinning, no commands to turn the program on, no
commands to turn it off, no extra bits in the program for user errors (such
as spinning in a puddle). Spinning is just a natural consequence of the
interactions (couplings) between the various subsystems, like the
synchronization of swinging arms behaving like coupled pendula. Such things
can be checked, by the way. Since the animal is coupled to the environment
as well, varying the conditions (such as height of grass, flexibility of
grass, circadian phase, etc. etc.) can produce different behaviors from
otherwise similar circumstances. If you vary things smoothly enough you
can even see transitions from one mode of behavior to another. What you
are probing in such cases is not a "motor program" but the self-organized,
emergent pattern formation process.
Center for Complex Systems and Brain Sciences The basis of
Florida Atlantic University, Boca Raton, FL 33431 USA stability is
tomh at bambi.ccs.fau.edu instability.