Journal of Neuroscience, Vol 8, 1500-1530, Copyright © 1988 by Society for Neuroscience
Functional anatomy of macaque striate cortex. I. Ocular dominance, binocular interactions, and baseline conditions
RB Tootell, SL Hamilton, MS Silverman and E Switkes
Department of Psychology, University of California, Berkeley 94720.
A series of experiments was carried out using 14C-2-deoxy-d-glucose (DG) in
order to examine the functional architecture of macaque striate (primary
visual) cortex. This paper describes the results of experiments on uptake
during various baseline (or reference) conditions of visual stimulation
(described below), and on differences in the functional architecture
following monocular versus binocular viewing conditions. In binocular
"baseline" experiments, monkeys were stimulated either (1) in the dark, (2)
with a diffuse gray screen, or (3) with a very general visual stimulus
composed of gratings of varied orientation and spatial frequency. In all of
these conditions, DG uptake was found to be topographically uniform within
all layers of parafoveal striate cortex. In monocular experiments that were
otherwise similar, uptake was topographically uniform within the full
extent of the eye dominance strip, in all layers. Certain other visual
stimuli produce high uptake in the blobs, and still another set of visual
stimuli (including high-spatial-frequency gratings) produce highest uptake
between the blobs at parafoveal eccentricities, even in an unanesthetized,
unparalyzed monkey. Eye movements per se had no obvious effect on striate
DG uptake. Endogenous uptake in the blobs (relative to that in the
interblobs) appears higher in the squirrel monkey than in the macaque. The
pattern of DG uptake produced by binocular viewing was found to deviate in
a number of ways from that expected by linearly summing the component
monocular DG patterns. One of the most interesting deviations was an
enhancement of the representation of visual field borders between stimuli
differing from each other in texture, orientation, direction, etc. This
"border enhancement" was confined to striate layers 1-3 (not appearing in
any of the striate input layers), and it only appeared following binocular,
but not monocular, viewing conditions. The border enhancement may be
related to a suppression of DG uptake that occurs during binocular viewing
conditions in layers 2 + 3 (and perhaps layers 1 and 4B), but not in layers
4Ca, 4Cb, 5 or 6. Another major class of binocular interaction was a spread
of neural activity into the "unstimulated" ocular dominance strips
following monocular stimulation. Such an effect was prominent in striate
layer 4Ca, but it did not occur in layer 4Cb. This "binocular" spread of DG
uptake into the inappropriate eye dominance strip in 4Ca may be related to
the appearance of orientation tuning and orientation columns in that layer.
No DG effects were seen that depended on the absolute disparity of visual
stimuli in macaque striate cortex.
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