Organization of ocular dominance peaks and pinwheel center singularities in
cat visual cortex.
Michael C. Crair, Edward S. Ruthazer, Deda C. Gillespie and Michael P.
Stryker.
W.M. Keck Foundation Center for Integrative Neuroscience, Department of
Physiology, University of California, San Francisco CA, 94143-0444.
APStracts 4:0069N, 1997.
ABSTRACT
In the primary visual cortex of monkey and cat, ocular dominance and
orientation are continuously and simultaneously represented, so that most
neighboring neurons respond optimally to visual stimulation of the same eye
and similar orientations (Hubel and Wiesel 1974; Hubel et al. 1978). Maps of
stimulus orientation are punctuated by singularities referred to as "pinwheel
centers" (Blasdel and Salama 1986; Bonhoeffer and Grinvald 1993), around which
all orientations are represented. Given that the orientation map is mostly
continuous, orientation singularities are a mathematical necessity unless the
map consists of perfectly parallel rows (Rojer and Schwartz 1990), and there
is no evidence that the singularities play a role in normal function or
development. We report here that in cats there is a strong tendency for peaks
of ocular dominance to lie on the pinwheel center singularities. This
relationship predicts but is not predicted by the tendencies, previously
reported, for pinwheels to lie near the center lines of ocular dominance bands
and for iso-orientation bands to cross ocular dominance boundaries at right
angles (Bartfeld and Grinvald 1992; Obermayer and Blasdel 1993; Hubener et al.
1995). The coincidence of ocular dominance peaks with orientation
singularities is likely to reflect a strong underlying functional link between
the two visual cortical maps (Durbin and Mitchison 1990; Kohonen 1989).
Received 24 December 1996; accepted in final form 7 February 1997.
APS Manuscript Number J999-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 5 March 1997