On the neurophysiological organization of binocular vision
Ralph D. Freeman, and Izumi Ohzawa (1990)
On the neurophysiological organization of binocular vision.
Vision Res. 30: 1661-1676.
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The considerable mixing in the visual cortex, of signals from left
and right eyes, provides an abundant population of binocularly activated
neurons. Based on this and on the fact that cortical cells respond best to
different ranges of retinal disparities, it has been proposed that these
neurons form the physiological substrate of stereoscopic depth
discrimination. We outline reasons here for addressing first the more
fundamental issue of the rules of convergence in the visual cortex, for
input from the two eyes. We show that most of this convergence may be
described by a linear summation process. However, there is a nonlinear
mechanism that maintains binocular interaction regardless of large
differences in stimulus strength between the eyes. This finding suggests
that a cell which appears to be dominated by one eye, when monocular tests
are conducted, may respond equally under binocular conditions. In this
case, binocular processing for all cortical cells could be uniform and
independent of the ocular dominance values determined monocularly. With
respect to a neural mechanism for the processing of information concerning
different depths in space, we propose an alternative to the conventional
notion. First, we identify fundamental problems with the current view.
Second, we describe a procedure which allows us to distinguish between the
conventional view and our alternative proposal. Standard receptive field
mapping techniques are not adequate for determining phase-disparity
relationships of the type we require. Therefore, we have employed a reverse
correlation procedure which enables efficient and detailed mapping of
receptive field structure. Third, we describe preliminary data concerning
the physiological mechanism of stereoscopic depth discrimination.
Additional on-line materials on the neural basis of stereopsis
Mathematica notebooks showing derivations and plots of model predictions.
Talk slides in Acrobat and PostScript.
Encoding of binocular disparity by complex cells in the cat's visual cortex.
(J. Neurophysiol. 77: 2879-2909, 1997)
Ohzawa, DeAngelis, Freeman
Encoding of binocular disparity by simple cells in the cat's visual cortex.
(J. Neurophysiol. 75: 1779-1805, 1996)
Ohzawa, DeAngelis, Freeman
Neuronal mechanisms underlying stereopsis: how do simple cells in the
visual cortex encode binocular disparity?
(Perception 24: 3-31, 1995)
DeAngelis, Ohzawa, Freeman
Monocular and binocular mechanisms of contrast gain control.
(Computational Vision based on Neurobiology, Proc. SPIE 2054: 43-51, 1994)