IUBio

Cross - Wired Eyes

SA nospam at nospam.net
Mon May 14 00:21:24 EST 2001


In article <GFlL6.27705$yd.199009 at typhoon.mw.mediaone.net>,
 "Richard Norman" <rsnorman at mediaone.net> wrote:

> "Karl Self" <karl.self at gmx.net> wrote in message
> news:9dkml6$insp0$1 at ID-34153.news.dfncis.de...
> >     Thanks for your speedy reply.  As always, new knowledge spawns new
> > questions ... (see below).
> >
> > "James Teo" <james at teoth.fsnet.co.uk> wrote:
> > ...
> > > Nobody knows. Good luck for your nobel prize.
> >
> >     Ta, but I can't right now.  I'm too busy trying to win me the Field
> > Medal and few Pullitzers.
> >
> > ...
> > > All sensory input crossover in humans before entering the hemispheres.
> >
> >     I hope I do not sound smart - arsed asking this:  so vision and
> hearing
> > are cross wired, but I guess taste isn't because it is not stereoscopic
> (or
> > do we have two tongue hemispheres)?  What about nostrils -- is smell
> > stereoscopic (can we smell left from right, and if not, what is the point
> of
> > having two nostrils rather than one (other than aesthetic reasons, maybe),
> > and are the nostrils cross - wired as well?
> >     Sorry to be so inflationary in my questioning.  I promise to be
> equally
> > inflationary in my appreciation of any forthcoming answers.
> 
> The vertebrate brain is crossed like you describe, but invertebrate brains
> are usually wired "correctly" -- the left side of the body is connected to
> the left side of the CNS.  There is really no point to the crossover -- it
> probably is an anomaly of the developmental genes controlling the
> bilateral body, distinguishing anterior from posterior, dorsal from ventral,
> and left from right.  Somewhere along the line, the left-right axis in the
> nervous system got mismatched.

No way hoser, the crossing allows neighboring cells to represent the 
same area of space from each eye allowing our system to make one of the 
depth calculations whcih uncrossed systems do not


> 
> I am not sure whether taste and smell are crossed -- I believe the
> special "visceral" senses are wired somewhat differently from the
> special "somatic" ones.  But there are indeed many animals that
> can accurately locate food sources by detecting the direction of
> taste and smell.  The "distance" sense of smell is more complex
> because odors are carried by air or water currents.  Often, on
> detecting an attractive weak odor, an animal will respond simply
> by swimming or flying upstream.  But then when the odor is strong
> enough, many animals can detect the gradient and definitely move
> towards to source.  Similarly, many animals use the contact
> chemical sense (the barbels of fish, for example) to explore their
> environment and to locate food.
> 
>




More information about the Neur-sci mailing list

Send comments to us at biosci-help [At] net.bio.net