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Speech and Chaos

Leslie Kay lmk2 at garnet.berkeley.edu
Sat Feb 6 15:08:03 EST 1993

In article <erwin.729019495 at trwacs> erwin at trwacs.fp.trw.com (Harry Erwin) writes:
>Dr. Huberman got on my case for being too vague, so I posted the
>following to him:
>If we look at what Freeman did we see the following: He postulated an
>underlying high-dimensional quasi-periodic process--imagine (this is how I
>see it) a field of dots, with the darkness of each dot varying
>similar terms, although the haze is not quasiperiodic.) If this haziness
>lasts long enough, the cortex eventually picks up on it and performs an
>orienting action.
>Now supplement this system with a collection of patterns downloaded to the
>olfactory bulb from the cortex. 

I'm not sure what exactly you mean here, but I don't believe that 
Freeman is advocating that any collection of patterns is "downloaded",
this seems to me to entirely short-circuit the beauty of a coupled
system, which ends up _producing_ coherent spatial patterns in the
bulb (and probably in the higher cortex as well).  If you mean that
the Prepyriform Cortex (PPC) activity is distributed spatially over
the bulb, then I agree with you.  But Freeman does not say that a 
pattern is delivered and "implanted" on the bulb intact from the PPC.

>Each pattern consists of a set of neuronal
>connections that are mutually excitory and that compete with other patterns.
>These perturb the quasiperiodic system described above non-linearly.
>If any pattern matches the current state of the image+ergodic haze, it is
>amplified, and, if it fails to match, it is weakened. This causes the overall
>state of the system to evolve, with the components of the scene that match
>patterns in the set becoming more and more distinct.  Eventually the system
>converges to one of the patterns and that is what is reported back to the

Actually, the connections are also mutually inhibitory and excitatory-
inhibitory.  Again, the system does not "report back" that it has reached
the downloaded pattern, but, as I understand it, it converges to one
pattern or another and that, with its interaction with the other areas
(AON, PPC and probably Entorhinal Cortex (EC)) _IS_ the perception.

Leslie Kay
UC Berkeley
lmk2 at garnet.berkeley.edu

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