From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!think.com!yale.edu!jvnc.net!darwin.sura.net!mojo.eng.umd.edu!mimsy!harwood Thu Dec 26 23:57:14 EST 1991
Article 2283 of comp.ai.philosophy:
Path: newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!think.com!yale.edu!jvnc.net!darwin.sura.net!mojo.eng.umd.edu!mimsy!harwood
>From: harwood@umiacs.umd.edu (David Harwood)
Newsgroups: comp.ai.philosophy
Subject: Re: Scaled up slug brains
Message-ID: <45210@mimsy.umd.edu>
Date: 19 Dec 91 17:48:50 GMT
References: <330@tdatirv.UUCP> <45102@mimsy.umd.edu> <12788@pitt.UUCP>
Sender: news@mimsy.umd.edu
Organization: UMIACS, University of Maryland, College Park, MD 20742
Lines: 69

In article <12788@pitt.UUCP> geb@dsl.pitt.edu (gordon e. banks) writes:
>In article <45102@mimsy.umd.edu> harwood@umiacs.umd.edu (David Harwood) writes:
>>	Virii? Do they have nervous systems?
>No, viruses do not have nervous systems.  Neither do primitive
>one celled or even multicellular organisms.
\\\\\\\\
	As you realize, I was just mildly complaining about your
passing comparison with virii, when we were discussing genetic 
contributions to major qualitative features of the brain. Which I 
suggested were due to apparently small genetic innovations. (Of course,
I've read that some cells of flies are manufactured by "programs"
of more than 100 consecutive gene instructions; I don't know how
many or complex are "programs" for cells supporting color vision, 
in the eye or in the LGN, for that matter.)
\\\\\\\\\\\\\\\

>>anatomical and physiological variation. Chimps may be 99+% like us,
>>but their brains do not have specialized language-processing areas,
>>and do not show related, major lateralization of function. A variation of
>
>Chimps do have major lateralization of function, as do most higher mammals.
>One of our biologists here is an expert on that.  He has studied it 
>extensively in voles (a rodent).  There are species of voles that are
>very lateralized and some that are not.  Both types live here in
>Pennsylvania.  As it turns out, the main distinguishing feature between
>the two species are that the lateralized ones are very territorial.
>His theory is that the lateralization occurred to provide specialization
>of spatial functions.  It just so happens that the right hemisphere is
>the one that does that in humans.  So I guess language just by
>default ended up in the left hemisphere where it had more "growing
>room".  Obviously things weren't that simple, but it's interesting
>to think about.  At any rate, lateralization is not a recent development
>keyed to language.
>
\\\\\\\\\\\\\
	I am willing to stand corrected about this. My education in
neuroscience and linguistics was many years ago, largely, although I've 
done some fairly recent computer research involving image analysis of
the retina (for detection of glaucoma) and of stained microscopic
pyramidal neurons.
	(My real work is logic-programming systems for computer vision and
robotics, and parallel computation for same. I am not opposed to using
or inventing NNs, for suitable purposes of pattern recognition. However,
many NN enthusiasts seem to be under the influence of what seems to me
to be a very "prophitable", pseudo-scientific, technological cult,
having very little to do with neuroscience - or artificial intelligence,
for that matter. As I remarked to someone, I sometimes wonder if these 
guys even know or care who are the DeValois, or Ramon Cajal, for that 
matter.)
	I was aware that some song-birds show both brain lateralization
correlated with a developmental period for learning their specific songs. 
And I was aware that some researchers recently have re-examined the
issue of handedness in monkeys, for example. I have not heard of
lateralization related to spatial function in animals, such as you
describe, related to territoriality. You see a big difference, though,
don't you? There is very direct psychological and neurological evidence
for laterization of function in humans, in many respects. You have not
(so far) made evidently clear what kind of function is supposed to
be involved, or what you mean by "lateralization." Also, in my other
example of bird-song, there is a correlation of lateralization  with
learning a function. Is this so for your case too?
	Anyway, I concede that that there may well be some sort of
lateralization of function in lower animals (such as some birds, and
perhaps others as well). I tried to hedge by saying "major lateralization
of brain functions" (as you quote me). I am still not aware that other
species show such pronounced lateralization of function as do humans
ordinarily. (This is not to say that humans cannot use or repair to
use both hemispheres, to some degree, with difficulties sometimes.)
D.H.


