Anisotropies in peripheral vernier acuity

Westheimer, Gerald

doi:10.1163/1568568053320611

Cited by 31 publications

(32 citation statements)

References 23 publications

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“…In addition to the oblique effect, a radial bias, which describes a biased representation of preferred orientations at particular angular positions, has also been shown in human psychophysics (Rovamo et al 1982; Davey and Zanker 1998; Westheimer 2003, 2005; Sasaki et al . 2006), animal neurophysiology (Leventhal 1983; Leventhal et al .…”

Section: Discussionmentioning

confidence: 96%

Demonstration of Tuning to Stimulus Orientation in the Human Visual Cortex: A High-Resolution fMRI Study with a Novel Continuous and Periodic Stimulation Paradigm

Sun

Gardner²,

Costagli

et al. 2012

Cerebral Cortex

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Cells in the animal early visual cortex are sensitive to contour orientations and form repeated structures known as orientation columns. At the behavioral level, there exist 2 well-known global biases in orientation perception (oblique effect and radial bias) in both animals and humans. However, their neural bases are still under debate. To unveil how these behavioral biases are achieved in the early visual cortex, we conducted high-resolution functional magnetic resonance imaging experiments with a novel continuous and periodic stimulation paradigm. By inserting resting recovery periods between successive stimulation periods and introducing a pair of orthogonal stimulation conditions that differed by 90° continuously, we focused on analyzing a blood oxygenation level-dependent response modulated by the change in stimulus orientation and reliably extracted orientation preferences of single voxels. We found that there are more voxels preferring horizontal and vertical orientations, a physiological substrate underlying the oblique effect, and that these over-representations of horizontal and vertical orientations are prevalent in the cortical regions near the horizontal- and vertical-meridian representations, a phenomenon related to the radial bias. Behaviorally, we also confirmed that there exists perceptual superiority for horizontal and vertical orientations around horizontal and vertical meridians, respectively. Our results, thus, refined the neural mechanisms of these 2 global biases in orientation perception.

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Section: Discussionmentioning

confidence: 96%

Demonstration of Tuning to Stimulus Orientation in the Human Visual Cortex: A High-Resolution fMRI Study with a Novel Continuous and Periodic Stimulation Paradigm

Sun

Gardner²,

Costagli

et al. 2012

Cerebral Cortex

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“…Three factors determine this precision. First, localization of peripheral targets is more precise in the direction than in the R direction (Yap et al, 1987;White et al, 1992;Westheimer, 2005). Second, localization precision in the direction displays a strong "oblique effect": precision is much better along the horizontal and vertical meridians than in oblique directions (White et al, 1992;Westheimer, 2001).…”

Section: Modelmentioning

confidence: 99%

“…Second, localization precision in the direction displays a strong "oblique effect": precision is much better along the horizontal and vertical meridians than in oblique directions (White et al, 1992;Westheimer, 2001). Third, localization precision varies across the visual field in the same way as visual acuity does (Yap et al, 1987;Levi and Klein, 1990;Aitsebaomo and Bedell, 1992;White et al, 1992;Westheimer, 2001Westheimer, , 2005. We quantified the first two factors using the values reported by White et al (1992): R / ϭ 6 for targets on the horizontal and vertical meridians, and R / ϭ 2 for targets in other directions.…”

Section: Modelmentioning

confidence: 99%

The Sources of Variability in Saccadic Eye Movements

Beers¹

2007

J. Neurosci.

164

146

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Our movements are variable, but the origin of this variability is poorly understood. We examined the sources of variability in human saccadic eye movements. In two experiments, we measured the spatiotemporal variability in saccade trajectories as a function of movement direction and amplitude. One of our new observations is that the variability in movement direction is smaller for purely horizontal and vertical saccades than for saccades in oblique directions. We also found that saccade amplitude, duration, and peak velocity are all correlated with one another. To determine the origin of the observed variability, we estimated the noise in motor commands from the observed spatiotemporal variability, while taking into account the variability resulting from uncertainty in localization of the target. This analysis revealed that uncertainty in target localization is the major source of variability in saccade endpoints, whereas noise in the magnitude of the motor commands explains a slightly smaller fraction. In addition, there is temporal variability such that saccades with a longer than average duration have a smaller than average peak velocity. This noise model has a large generality because it correctly predicts the variability in other data sets, which contain saccades starting from very different initial locations. Because the temporal noise most likely originates in movement planning, and the motor command noise in movement execution, we conclude that uncertainty in sensory signals and noise in movement planning and execution all contribute to the variability in saccade trajectories. These results are important for understanding how the brain controls movement.

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“…Results of our studies also suggest that the anisotropy in vernier acuity might have its origin in the statistics of natural scenes. Evidence in support of these suggestions can be found in 26 , where it was argued that the vernier misalignment can be discussed on the premise that the average orientation of a misaligned pair of abutting lines differs from that of the aligned lines. Vernier acuity preferring horizontal directions over the vertical including the cardinal over the oblique has been demonstrated in this work.…”

Section: Discussionmentioning

confidence: 97%

Significance of Natural Scene Statistics in Understanding the Anisotropies of Perceptual Filling-in at the Blind Spot

Raman

Sarkar

2017

Sci Rep

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Psychophysical experiments reveal our horizontal preference in perceptual filling-in at the blind spot. On the other hand, tolerance in filling-in exhibit vertical preference. What causes this anisotropy in our perception? Building upon the general notion that the functional properties of the early visual system are shaped by the innate specification as well as the statistics of the environment, we reasoned that the anisotropy in filling-in could be understood in terms of anisotropy in orientation distribution inherent in natural scene statistics. We examined this proposition by investigating filling-in of bar stimuli in a Hierarchical Predictive Coding model network. The model network, trained with natural images, exhibited anisotropic filling-in performance at the blind spot, which is similar to the findings of psychophysical experiments. We suggest that the over-representation of horizontal contours in the natural scene contributes to the observed horizontal superiority in filling-in and the broader distribution of vertical contours contributes to the observed vertical superiority of tolerance in filling-in. These results indicate that natural scene statistics plays a significant role in determining the filling-in performance at the blind spot and shaping the associated anisotropies.

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Anisotropies in peripheral vernier acuity

Cited by 31 publications

References 23 publications

Demonstration of Tuning to Stimulus Orientation in the Human Visual Cortex: A High-Resolution fMRI Study with a Novel Continuous and Periodic Stimulation Paradigm

Demonstration of Tuning to Stimulus Orientation in the Human Visual Cortex: A High-Resolution fMRI Study with a Novel Continuous and Periodic Stimulation Paradigm

The Sources of Variability in Saccadic Eye Movements

Significance of Natural Scene Statistics in Understanding the Anisotropies of Perceptual Filling-in at the Blind Spot

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