Structures organizing perception?

[From Bruce Buchanan 941007.21:10 EDT]

I have been studying B:CP to correct and refine my understanding (I had
previously read Living Controls Systems I & II collections of papers, but
still seemed to have some 'sand in the gears' in relation to PCT).

Now I have another question which seems to me fairly fundamental.

I understand that for PCT all primary or first-order inputs are seen in
terms of 'neural currents', and that all information and higher-order
derivatives are also seen in these terms. But I also recall from physiology
that sensory stimuli are received and interpreted initially by quite
specific sense organs, - for physical modalities such as touch, pressure,
pain, temperature, as well as chemical (taste buds for sour, sweet, etc.),
in addition to sight, sound, and other specific senses, including
equilibrium (hair cells) etc. etc..

In short, the messages of neural currents depend precisely on the type of
sensory organ or transducer from which they originate. In addition, as I
recall, the fibres which carry the neural currents develop embryonically to
run and project to specific reception areas within the brain, and
perception also depends in some important ways on such areas and regions,
over and above the other neural currents that also report there. I have
therefore had the idea that some qualitative and spatial configurations are
already built into the brain structurally as well as functionally, probably
those which reflect aspects of the environment which most impact upon the
organism. In other words, as I see it, there are structures which reflect
the real world already built into the brain, as well as the body, which
provide the operating framework which makes it possible for any neural
analogue mechanism to function.

Perhaps these factors may condition perceptions, and constrain ways and
degrees of possible control, but not affect basic PCT?

But questions do remain for me. Does PCT take into account these
determinants of content and organization of information and perception?
Does such a framework of preconditions have any implications for
potentially controlling variables? My own surmise is that something more
than variables which may reflect e.g. tissue nutrition, may be involved,
but I am far from certain.

To what extent can PCT, which seems to me to be entirely valid as far as it
goes, be considered a complete theory of behavior and perception?

Maybe I am still just confused. If this topic has been discussed somewhere
at length, a brief pointer in the right direction would be appreciated.

Cheers!

Bruce B.