Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!mcnc!rti!xyzzy!bert!throopw From: throopw@bert.dg.com (Wayne A. Throop) Newsgroups: comp.ai Subject: Re: "Boss, look: da brain, da Brain!" Keywords: symbols representations neural Message-ID: <5009@xyzzy.UUCP> Date: 10 Apr 89 02:41:23 GMT References: <10982@bcsaic.UUCP> Sender: usenet@xyzzy.UUCP Lines: 42 > ray@bcsaic.UUCP (Ray Allis) >> throopw@agarn.dg.com (Wayne A. Throop) >> no case has been made for how much of the "analogness" of the >> signal that makes its way to the brain is significant. > I assert that the "analogness" is absolutely critical. My case is based on > the fundamental difference between _representations_ and _symbols_. (i.e. > the voltages, frequencies, chemical concentrations and so on are > _representations_ of "external reality" rather than symbols. This seems not to be the case, especially in the visual cortex. The firing of a given neuron does not *represent* "a vertical line so long" in any discernable way, and yet this happens at quite a low level of processing. Even the processing that winds up calculating "color" is not a very simple "representation" of the extent of stimulation of the three varieties of color-sensitive sensors in the retina... if one could even warp "representation" to cover it at all. The point is, that even at rather low, automatic levels of processing in the brain, features of the percept are calculated that are very, very symbol-like, and not very representation-like at all. Thus, as I started out, I'd say that this > Symbols appear > at a much "higher" level of cognition, where _representations_ can be > associated with each other. seems an interesting theory... but not to be the case. > What evidence? Is there neurological evidence? The neurological research > I've seen does seem to point to a series of analog transforms. Do you have > some references, please? I don't have the original research referents handy. They were given in the credits of the episode of "The Brain" on PBS, and in the various accounts of this research as reported in Science News and the like. -- Indeed he knows not how to know who knows not how to un-know. --- Sir Richard Francis Burton -- Wayne Throop !mcnc!rti!xyzzy!throopw