The Site of Binocular Rivalry Suppression

Perception ◽  
1979 ◽  
Vol 8 (2) ◽  
pp. 143-152 ◽  
Author(s):  
Randolph Blake ◽  
Randall Overton
Keyword(s):  
Visual System ◽  
Binocular Rivalry ◽  
Human Visual System ◽  
Striate Cortex ◽  
High Contrast ◽  
Threshold Elevation ◽  
Short Term ◽  
Contrast Adaptation ◽  
A Site ◽  
Lines Of Evidence

Two experiments were performed to localize the site of binocular rivalry suppression in relation to the locus of grating adaptation. In one experiment it was found that phenomenal suppression of a high-contrast adaptation grating presented to one eye had no influence on the strength of the threshold-elevation aftereffect measured interocularly. Evidently information about the adaptation grating arrives at the site of the aftereffect (presumably binocular neurons) even during suppression. In a second experiment 60 s of grating adaptation was found to produce a short-term reduction in the predominance of the adapted eye during binocular rivalry. These findings provide converging lines of evidence that suppression occurs at a site in the human visual system after the locus of grating adaptation and, hence, after the striate cortex.

Apparent Foveofugal Drift of Counterphase Gratings

Perception ◽  
1978 ◽  
Vol 7 (5) ◽  
pp. 527-536 ◽  
Author(s):  
Mark A Georgeson ◽  
Michael G Harris
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Human Visual System ◽  
Directional Asymmetry ◽  
Retinal Periphery ◽  
Visual Flow ◽  
Lines Of Evidence

Counterphase gratings, and several other stimuli which consist of equal components of motion in both directions, appeared to drift foveofugally, rather than foveopetally, when presented to the retinal periphery. This ‘foveofugal drift effect’ was demonstrated by descriptive and nulling techniques and its magnitude was shown to vary across subjects. The effect was fairly brief under continuous fixation. Several lines of evidence suggested that eye movements were not responsible for the effect. The phenomenon implies a directional asymmetry in the human visual system which may be related to our consistent exposure to expanding patterns of visual flow.

Orientation Detectors in the Human Visual System and Figurai Aftereffects

Perception ◽  
1978 ◽  
Vol 7 (6) ◽  
pp. 717-723 ◽  
Author(s):  
Toshiro Yoshida
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Apparent Size ◽  
Relative Influence ◽  
Test Figure ◽  
High Contrast ◽  
Outer Contour ◽  
Outer Border ◽  
High Contrast Grating ◽  
Potent Factor

Figurai aftereffects were measured by using square patches of high-contrast grating on a dark background as inspection and test figures. The orientation of the outer square border and the enclosed grating were varied independently in order to evaluate their relative influence on the strength of the induced change of overall apparent size of the test figure. The largest effect is obtained when inspection and test figures are identical in the orientation of both outer border and enclosed grating. The strength of the aftereffect is reduced as a difference in orientation is introduced between inspection and test figure for either the outer contour or the contained grating, although the former is a more potent factor than the latter.

scholarly journals The Spatial Extent of Short-Term Plasticity Effects in the Human Visual System

2015 ◽  
Vol 15 (12) ◽  
pp. 998
Author(s):  
Matthew Gannon ◽  
Stephanie Long ◽  
Nathan Parks
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Spatial Extent ◽  
Short Term ◽  
Short Term Plasticity

Are Curves Detected by ‘Curvature Detectors’?

Perception ◽  
1978 ◽  
Vol 7 (1) ◽  
pp. 51-64 ◽  
Author(s):  
Brian N Timney ◽  
Colin Macdonald
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Human Vision ◽  
Orientation Tuning ◽  
Threshold Elevation ◽  
Maximum Value ◽  
Adaptation Experiment ◽  
The Relationship

Five experiments which attempted to evaluate the relationship between orientation and curvature selectivity in human vision are described. In the first two experiments, threshold elevation for curved gratings was measured after exposure to similar gratings, with the use of either an adaptation (experiment 1) or a masking (experiment 2) paradigm. In both experiments threshold elevation occurred which was selective for both the degree and the direction of curvature of the adapting pattern. Experiment 3 compared the effects of adapting to tilted rectilinear or vertical curved gratings upon threshold for a vertical rectilinear grating. Threshold elevation declined systematically as the adapting gratings were either tilted or made more curved. Experiment 4 measured curvature selectivity as a function of the orientation of a curved adapting grating. Threshold elevation declined as the adapting grating was tilted more, but curvature selectivity remained. Experiment 5 measured the orientation tuning for curved gratings directly. Threshold elevation declined to 50% of its maximum value at an adapting orientation of about 28°. This was constant for all values of curvature used. The results are discussed with reference to the question of whether the human visual system contains ‘curvature detectors’ or linear-contour detectors which respond to the tangents of curves.

Contrast adaptation and excitatory amino acid receptors in cat striate cortex

1996 ◽  
Vol 13 (6) ◽  
pp. 1069-1087 ◽  
Author(s):  
J. McLean ◽  
L.A. Palmer
Keyword(s):  
Striate Cortex ◽  
Excitatory Amino Acid ◽  
Gain Control ◽  
Visual Response ◽  
High Contrast ◽  
Amino Acid Receptors ◽  
Contrast Gain ◽  
Contrast Adaptation ◽  
Contrast Response ◽  
Cat Striate Cortex

AbstractWe have employed two paradigms to investigate the mechanisms of contrast gain control in cat striate cortex. In the first paradigm, optimal drifting gratings were presented in three consecutive periods. The contrast was near threshold in the first and third periods and accompanied by iontophoretic pulses of glutamate or glutamate receptor (GluR) agonists. The contrast was set to evoke a higher firing rate in the second period. Although both visual and iontophoretic conditions were identical in the first and third periods, responses to glutamate, N-methyl-D-aspartic acid (NMDA), and (1S, 3R)-1-Aminocyclopentane-1, 3-dicarboxylic acid (ACPD) were reduced following the adapting interval. (S)-α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) responses were not reduced. Administration of ionotropic GluR antagonists did not affect adaptation to the high-contrast grating. The metabotropic GluR antagonist (±)-α-Methyl-4-carboxyphenylglycine (MCPG), which acts at presynaptic glutamate autoreceptors, decreased the degree of adaptation exhibited by striate cells. In a second paradigm, contrast response functions (CRFs) were obtained at various adapting contrasts and least-squares fits to a hyperbolic ratio equation generated for each adapting level. Similar to previous reports, DL-2-amino-5-phosphonovaleric acid (APV) reduced the slope of the CRF and increased the responsiveness of the cells but did not affect the semisaturation constant, σ, or the exponent of the CRF, n. Only MCPG significantly altered the distribution of σ and n for 19 cells. The effect on α suggests that this drug can interfere with the cell's ability to shift its operating point to match the adapting contrast. These results suggest the involvement of a presynaptic mechanism for contrast adaptation. The decrease in neuronal responsiveness immediately following the high-contrast period may reflect an additional, postsynaptic effect in which there is a decrease in the NMDA-mediated component of the visual response.

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