Journal of Neuroscience, Vol 6, 823-836, Copyright © 1986 by Society for Neuroscience
Retinal constraints on orientation specificity in cat visual cortex
JD Schall, DJ Vitek and AG Leventhal
Most retinal ganglion cells (Levick and Thibos, 1982) and cortical cells
(Leventhal, 1983; Leventhal et al., 1984) subserving peripheral vision
respond best to stimuli that are oriented radially, i.e., like the spokes
of a wheel with the area centralis at the hub. We have extended this work
by comparing directly the distributions of orientations represented in
topographically corresponding regions of retina and visual cortex. Both
central and peripheral regions were studied. The relations between the
orientations of neighboring ganglion cells and the manner in which the
overrepresentation of radial orientations is accommodated in the functional
architecture of visual cortex were also studied. Our results are based on
an analysis of the orientations of the dendritic fields of 1296 ganglion
cells throughout the retina and the preferred orientations of 1389 cells
located in retinotopically corresponding regions of cortical areas 17, 18,
and 19 in the cat. We find that horizontal and vertical orientations are
overrepresented in regions of both retina and visual cortex subserving the
central 5 degrees of vision. The distributions of the orientations of
retinal ganglion cells and cortical cells subserving the horizontal,
vertical, and diagonal meridians outside the area centralis differ
significantly. The distribution of the preferred orientations of the S
(simple) cells in areas 17, 18 and 19 subserving a given part of the retina
corresponds to the distribution of the dendritic field orientations of the
ganglion cells in that part of retina. The distribution of the preferred
orientations of C (complex) cells with narrow receptive fields in area 17
but not C cells with wide receptive fields in areas 17, 18, or 19
subserving a given part of the retina matches the distribution of the
orientations of the ganglion cells in that part of retina. The orientations
of all of the alpha-cells in 5-9 mm2 patches of retina along the
horizontal, vertical, and oblique meridians were determined. A comparison
of the orientations of neighboring cells indicates that other than a mutual
tendency to be oriented radially, ganglion cells with similar orientations
are not clustered in the retina. Reconstructions of electrode penetrations
into regions of visual cortex representing peripheral retina indicate that
columns subserving radial orientations are wider than those subserving
nonradial orientations. Our results provide evidence that the distribution
of the preferred orientations of simple cells in visual cortex subserving
any region of the visual field matches the distribution of the orientations
of the ganglion cells subserving the same region of the visual
field.(ABSTRACT TRUNCATED AT 400 WORDS)