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[Klaus Obermayer]

The following article is available as a (hardcopy) preprint:

Obermayer K. and Blasdel G.G. (1993), Geometry of Orientation and 
Ocular Dominance Columns in Monkey Striate Cortex, J. Neurosci., 
in press.

Abstract:

In addition to showing that ocular dominance is organized in slabs 
and that orientation preferences are organized in linear sequences 
likely to reflect slabs, Hubel and Wiesel (1974) discussed the 
intriguing possibility that slabs of orientation might intersect 
slabs of ocular dominance at some consistent angle. Advances in 
optical imaging now make it possible to test this possibility 
directly. When maps of orientation are analyzed quantitatively, 
they appear to arise from a combination of at least two competing 
themes: one where orientation preferences change linearly along 
straight axes, remaining constant along perpendicular axes and 
forming iso-orientation slabs along the way, and one where 
orientation preferences change continuously along circular axes, 
remaining constant along radial axes and forming singularities at 
the centers of the spaces enclosed. When orientation patterns are 
compared with ocular dominance patterns from the same cortical 
regions, quantitative measures reveal: 1) that singularities tend 
to lie at the centers of ocular dominance columns, 2) that linear 
zones (arising where orientation preferences change along straight 
axes) tend to lie at the edges of ocular dominance columns, and 3) 
that the short iso-orientation bands within each linear zone tend 
to intersect the borders of ocular dominance slabs at angles of 
approximately 90$^o$. 

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The original article contains color figures which - for cost 
reasons - have to be reproduced black and white. If you would like
to obtain a copy, please send your surface mail address to:

                       Klaus Obermayer 
                 The Rockefeller University
                 oby at rockvax.rockefeller.edu

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