[From Bruce Abbott (971217.2015 EST)]
Bill Powers (971217.1212 MST) --
Do medical researchers check to see
whether a treatment has destroyed someone's ability to factor polynomials?
To categorize usefully? To control relationships? To grasp principles? Do
they measure loop gains before and after treatment, to see if simple or
complex control systems have lost some stability, or some bandwidth, or
some range of control? I think you know the answer to that: they do not;
such ideas mean nothing to them. They don't see destructive effects mainly
because their tests for system function are too primitive to pick up any
but the most obvious malfunctions. Not only that, but destructive effects
that are observed are termed "side-effects," which, unless they are
perceived as serious, are usually ignored. Effects which are entirely
subjective, such as a feeling of dullness or ennui, are not objectively
measurable, and the judgement of whether they are serious is heavily biased
against giving them much weight.
One condition where drug intervention may relate rather precisely to
control-system action is bipolar affective disorder (formerly known as
manic-depressive psychosis). In this disorder a person swings between
states of mania (hyper-excited, like a person high on speed, and delusional)
and deep clininal depression (completely lacking in energy, has difficulty
thinking and initiating voluntary movement, irrational thought processes).
These swings follow a regular period of days, weeks, or months. My guess is
that it represents a regulatory failure -- the system in question has some
serious lags in it, so that it "hunts" around the reference level,
overshooting and undershooting, rather than stabilizing near the reference.
Most likely there is at first an overproduction of certain receptors in the
relevant neural system, leading to a hyperactive state; when this imbalance
is finally detected, the receptor numbers are reduced, but this process is
carried too far, leading to a hypoactive state with associated physical and
emotional depression. Lithium chloride (a drug used to treat the disorder)
appears to stabilize the system, perhaps by slowing the regulatory changes
in receptor densities. I know that this is pure speculation on my part, but
I can't help but think that something like this is at work. The question
is, how to test the theory.
It would appear that this is one disorder for which "talk therapy" (even
PCT-style) is not the answer. Even so, PCT may provide a framework for
analyzing the problem at the physical systems level. Oscillation is a
well-known defect in control systems whose parameters are not properly "tuned."
Regards,
Bruce