Visual Cortex Columns Question

Richard Norman rsnorman at mediaone.net
Mon Nov 20 21:14:16 EST 2000


"Richard Vickery" <Richard.Vickery at unsw.edu.au> wrote in message
news:3A19B6F0.18F67AF3 at unsw.edu.au...
> mike wrote:
> >
> >  I am not sure how i want to phrase this question, but what purpose do
the
> > Ocular dominance, and Orientation columns in the visual cortex serve?
> > Hope that makes some sort of sense.
>
> Because of the laminar structure of cortex, columns make evolutionary
> sense - combining similar inputs and keeping the wiring simple.
> Purpose is harder to answer, as you could devise alternate schemes
> that functioned without columns.  I believe the essence is to
> facilitate re-inforcement and suppression - so that activity in a
> given orientation column tends to lead to more activity in that column
> and suppression of activity in neighbouring columns of different
> orientation.
>
>
> --
> Dr Richard Vickery
> School of Physiology & Pharmacology, UNSW, Australia, 2052
> ph. 61 2 93851676,  fax 61 2 93851059
> http://www.med.unsw.edu.au/Physiology/School/staff/vickery/Welcome.html

I seem to recall on old paper (ca. the 60's) of D. MacKay (sp?) pointing out
that disparity in the orientation vector between the two eyes is an
important
component of depth perception.  That is, if you look at a stick, you see a
straight line at some orientation angle.  However, if one end of the stick
is
closer to you than the other, the orientation angle varies between the two
eyes.  (Try it, it's true!)

Therefore, keeping the orientation angle information separate from the
ocular dominance information allows the appropriate processing to
detect the depth effect.









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