Visual hyperacuity: spatiotemporal interpolation in human vision

1981 ◽  
Vol 213 (1193) ◽  
pp. 451-477 ◽  
Keyword(s):  
Constant Velocity ◽  
Receptive Fields ◽  
Spatial Separation ◽  
Human Vision ◽  
Interpolation Process ◽  
Vernier Acuity ◽  
Optimal Velocity ◽  
Temporal Properties ◽  
Wide Range ◽  
Temporal Offset

Stroboscopic presentation of a moving object can be interpolated by our visual system into the perception of continuous motion. The precision of this interpolation process has been explored by measuring the vernier discrimination threshold for targets displayed stroboscopically at a sequence of stations. The vernier targets, moving at constant velocity, were presented either with a spatial offset or with a temporal offset or with both. The main results are: (1) vernier acuity for spatial offset is rather invariant over a wide range of velocities and separations between the stations (see Westheimer & McKee 1975); (2) vernier acuity for temporal offset depends on spatial separation and velocity. At each separation there is an optimal velocity such that the strobe interval is roughly constant at about 30 ms; optimal acuity decreases with increasing separation; (3) blur of the vernier pattern decreases acuity for spatial offsets, but improves acuity for temporal offsets (at high velocities and large separations); (4) a temporal offset exactly compensates the equivalent (at the given velocity) spatial offset only for a small separation and optimal velocity; otherwise the spatial offset dominates. A theoretical analysis of the interpolation problem suggests a computational scheme based on the assumption of constant velocity motion. This assumption reflects a constraint satisfied in normal vision over the short times and small distances normally relevant for the interpolation process. A reasonable implementation of this scheme only requires a set of independent, direction selective spatiotemporal channels, that is receptive fields with the different sizes and temporal properties revealed by psychophysical experiments. It is concluded that sophisticated mechanisms are not required to account for the main properties of vernier acuity with moving targets. It is furthermore suggested that the spatiotemporal channels of human vision may be the interpolation filters themselves. Possible neurophysiological implications are briefly discussed.

Spatial and Temporal Properties of Stereoscopic Surface Interpolation

Perception ◽  
10.1068/p5437 ◽  
2005 ◽  
Vol 34 (11) ◽  
pp. 1325-1338 ◽  
Author(s):  
Laurie M Wilcox ◽  
Philip A Duke
Keyword(s):  
Exposure Duration ◽  
Critical Value ◽  
Stereoscopic Vision ◽  
Interpolation Process ◽  
Temporal Constraints ◽  
Shape Discrimination ◽  
Surface Interpolation ◽  
Temporal Properties ◽  
Texture Density ◽  
Wide Range

It is well established that under a wide range of conditions when a sparse collection of texture elements varies smoothly in depth, the spaces between the elements are assigned depth values. This disparity interpolation process has been studied in an effort to define some of its fundamental spatial and temporal constraints. To assess disparity interpolation we employed two tasks: a novel task that relies on the bisection of illusory boundaries created when subjective stereoscopic surfaces intersect, and one that relies on a 3-D shape discrimination. The results of both experiments show that there is no improvement in performance when texture density is increased from near 0.20 to 0.85 or when exposure duration is increased from 50–100 to 1000 ms. This lack of dependence on the addition of features that define the interpolated surface, along with the abrupt decline in performance below a critical value, is consistent with the view that surface interpolation is an important function of human stereoscopic vision.

Signals and noise in the elasmobranch electrosensory system

1999 ◽  
Vol 202 (10) ◽  
pp. 1349-1355 ◽  
Author(s):  
J.C. Montgomery ◽  
D. Bodznick
Keyword(s):  
Direct Current ◽  
Noise Suppression ◽  
Receptive Fields ◽  
Sensory System ◽  
Mate Recognition ◽  
Common Mode ◽  
Central Processing ◽  
Temporal Properties ◽  
Efferent Neurons ◽  
Bioelectric Fields

Analyzing signal and noise for any sensory system requires an appreciation of the biological and physical milieu of the animal. Behavioral studies show that elasmobranchs use their electrosensory systems extensively for prey detection, but also for mate recognition and possibly for navigation. These biologically important signals are detected against a background of self-generated bioelectric fields. Noise-suppression mechanisms can be recognized at a number of different levels: behavior, receptor anatomy and physiology, and at the early stages of sensory processing. The peripheral filters and receptor characteristics provide a detector with permissive temporal properties but restrictive spatial characteristics. Biologically important signals probably cover the range from direct current to 10 Hz, whereas the bandwidth of the receptors is more like 0.1-10 Hz. This degree of alternating current coupling overcomes significant noise problems while still allowing the animal to detect external direct current signals by its own movement. Self-generated bioelectric fields modulated by breathing movement have similar temporal characteristics to important external signals and produce very strong modulation of electrosensory afferents. This sensory reafference is essentially similar, or common-mode, across all afferent fibers. The principal electrosensory neurons (ascending efferent neurons; AENs) of the dorsal octavolateralis nucleus show a greatly reduced response to common-mode signals. This suppression is mediated by the balanced excitatory and inhibitory components of their spatial receptive fields. The receptive field characteristics of AENs determine the information extracted from external stimuli for further central processing.

scholarly journals Neural network models of the tactile system develop first-order units with spatially complex receptive fields

2017 ◽  
Author(s):  
Charlie W. Zhao ◽  
Mark J. Daley ◽  
J. Andrew Pruszynski
Keyword(s):  
Neural Network ◽  
Network Performance ◽  
Receptive Fields ◽  
Network Models ◽  
Network Architectures ◽  
Learning Tools ◽  
Neural Network Models ◽  
First Order ◽  
Wide Range ◽  
Tactile System

AbstractFirst-order tactile neurons have spatially complex receptive fields. Here we use machine learning tools to show that such complexity arises for a wide range of training sets and network architectures, and benefits network performance, especially on more difficult tasks and in the presence of noise. Our work suggests that spatially complex receptive fields are normatively good given the biological constraints of the tactile periphery.

scholarly journals Retinal Synaptic Pathways Underlying the Response of the Rabbit Local Edge Detector

2010 ◽  
Vol 103 (5) ◽  
pp. 2757-2769 ◽  
Author(s):  
Thomas L. Russell ◽  
Frank S. Werblin
Keyword(s):  
Feedback Inhibition ◽  
Receptive Fields ◽  
Cell Voltage ◽  
Retinal Ganglion ◽  
Edge Detector ◽  
Temporal Properties ◽  
Field Sensitivity ◽  
Glycinergic Inhibition ◽  
Local Edge ◽  
Feedforward Inhibition

We studied the circuitry that underlies the behavior of the local edge detector (LED) retinal ganglion cell in rabbit by measuring the spatial and temporal properties of excitatory and inhibitory currents under whole cell voltage clamp. Previous work showed that LED excitation is suppressed by activity in the surround. However, the contributions of outer and inner retina to this characteristic and the neurotransmitters used are currently unknown. Blockage of retinal inhibitory pathways (GABAA, GABAC, and glycine) eliminated edge selectivity. Inverting gratings in the surround with 50-μm stripe sizes did not stimulate horizontal cells, but suppressed on and off excitation by roughly 60%, indicating inhibition of bipolar terminals (feedback inhibition). On pharmacologic blockage, we showed that feedback inhibition used both GABAA and GABAC receptors, but not glycine. Glycinergic inhibition suppressed GABAergic feedback inhibition in the center, enabling larger excitatory currents in response to luminance changes. Excitation, feedback inhibition, and direct (feedforward) inhibition responded to luminance-neutral flipping gratings of 20- to 50-μm widths, showing they are driven by independent subunits within their receptive fields, which confers sensitivity to borders between areas of texture and nontexture. Feedforward inhibition was glycinergic, its rise time was faster than decay time, and did not function to delay spiking at the onset of a stimulus. Both the on and off phases could be triggered by luminance shifts as short in duration as 33 ms and could be triggered during scenes that already produced a high baseline level of feedforward inhibition. Our results show how LED circuitry can use subreceptive field sensitivity to detect visual edges via the interaction between excitation and feedback inhibition and also respond to rapid luminance shifts within a rapidly changing scene by producing feedforward inhibition.

Early Motion Processes and the Kinetic Depth Effect

1989 ◽  
Vol 41 (1) ◽  
pp. 183-198 ◽  
Author(s):  
George Mather
Keyword(s):  
Depth Perception ◽  
Short Range ◽  
Three Dimensional ◽  
Visual Display ◽  
Depth Effect ◽  
Temporal Properties ◽  
Early Motion ◽  
Wide Range ◽  
Dimensional Object ◽  
Inter Frame

It has been known for over 30 years that motion information alone is sufficient to yield a vivid impression of three-dimensional object structure. For example, a computer simulation of a transparent sphere, the surface of which is randomly speckled with dots, gives no impression of depth when presented as a stationary pattern on a visual display. As soon as the sphere is made to rotate in a series of discrete steps or frames, its 3-D structure becomes apparent. Three experiments are described which use this stimulus, and find that depth perception in these conditions depends crucially on the spatial and temporal properties of the display: 1. Depth is seen reliably only for between-frame rotations of less than 15°, using two-frame and four-frame sequences. 2. Parametric observations using a wide range of frame durations and inter-frame intervals reveal that depth is seen only for inter-frame intervals below 80 msec and is optimal when the stimulus can be sampled at intervals of about 40–60 msec. 3. Monoptic presentation of two frames of the stimulus is sufficient to yield depth, but the impression is destroyed by dichoptic presentation. These data are in close agreement with the observed limits of direction perception in experiments using “short-range” stimuli. It is concluded that depth perception in the motion display used in these experiments depends on the outputs of low-level or “short-range” motion detectors.

Visual responses of pulvinar and collicular neurons during eye movements of awake, trained macaques

1991 ◽  
Vol 66 (2) ◽  
pp. 485-496 ◽  
Author(s):  
D. L. Robinson ◽  
J. W. McClurkin ◽  
C. Kertzman ◽  
S. E. Petersen
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Receptive Fields ◽  
Visual Responses ◽  
Stimulus Motion ◽  
Stimulus Movement ◽  
Pursuit Eye Movements ◽  
Extraretinal Signal ◽  
Wide Range

1. We recorded from single neurons in awake, trained rhesus monkeys in a lighted environment and compared responses to stimulus movement during periods of fixation with those to motion caused by saccadic or pursuit eye movements. Neurons in the inferior pulvinar (PI), lateral pulvinar (PL), and superior colliculus were tested. 2. Cells in PI and PL respond to stimulus movement over a wide range of speeds. Some of these cells do not respond to comparable stimulus motion, or discharge only weakly, when it is generated by saccadic or pursuit eye movements. Other neurons respond equivalently to both types of motion. Cells in the superficial layers of the superior colliculus have similar properties to those in PI and PL. 3. When tested in the dark to reduce visual stimulation from the background, cells in PI and PL still do not respond to motion generated by eye movements. Some of these cells have a suppression of activity after saccadic eye movements made in total darkness. These data suggest that an extraretinal signal suppresses responses to visual stimuli during eye movements. 4. The suppression of responses to stimuli during eye movements is not an absolute effect. Images brighter than 2.0 log units above background illumination evoke responses from cells in PI and PL. The suppression appears stronger in the superior colliculus than in PI and PL. 5. These experiments demonstrate that many cells in PI and PL have a suppression of their responses to stimuli that cross their receptive fields during eye movements. These cells are probably suppressed by an extraretinal signal. Comparable effects are present in the superficial layers of the superior colliculus. These properties in PI and PL may reflect the function of the ascending tectopulvinar system.

The impact of LTE-FDD at the LTE-TDD for the co-existence under 2.6 GHz band for Malaysia

2016 ◽  
Vol 2 (3) ◽  
pp. 657 ◽  
Author(s):  
L.M. Ahmed ◽  
M.F.L. Abdullah
Keyword(s):  
Spatial Separation ◽  
Loss Ratio ◽  
Frequency Allocation ◽  
Edge Point ◽  
Wide Range ◽  
Two Systems ◽  
The Impact

For the co-existence scenario between LTE-FDD and LTE-TDD systems, if the two systems are using an adjacent frequency carrier, there will be a need for spatial separation between the eNodeBs of the two systems, otherwise the two systems will interfere each other. The study is implemented based on realistic parameters in order to help the network designer to make a decision about the best frequency allocation and network deployments in order to achieve higher performance under the lowest possible cost. Throughout this paper, the effect of the FDD system at the TDD is evaluated under wide range of ACIR and separation distances between the two systems eNodeBs as well. The results showed that, the recommended ACIR offset by the 3GPP is not enough for the LTE-TDD uplink throughput loss ratio to be acceptable, whereas 115 dB, 45 dB, and 35 dB of the ACIR is required for the throughput loss ratio in order to drop less than 5% for the co-located, Mid-point, and Edge-point eNodeBs deployment scenario respectively. Meanwhile, comparing to the uplink case, the downlink of the TDD system is much coherent; the recommended ACIR offset is only unacceptable for the co-located deployment case, whereas 50 dB of the ACIR is required for the system to drop less than 5%.

White-light solar corona structure observed by naked eye and processed images

2020 ◽  
Vol 495 (2) ◽  
pp. 2170-2178 ◽  
Author(s):  
Vojtech Rušin ◽  
Paul Prikryl ◽  
Emil A Prikryl
Keyword(s):  
Solar Wind ◽  
White Light ◽  
High Speed ◽  
Geomagnetic Storms ◽  
Interplanetary Space ◽  
Coronal Holes ◽  
Human Vision ◽  
Naked Eye ◽  
Wide Range ◽  
White Light Corona

ABSTRACT Light and dark adaptation and luminance contrast enhancement are well-known characteristics of human vision that allow us to observe a wide range of light intensity not fully captured in standard camera images. The naked-eye observations of total eclipses, some recorded with spectacular detail in artists’ paintings, reveal structure that is consistent with images obtained by telescopes equipped with recording media. The actual shape of the corona during a total eclipse depends not only on the phase of the solar cycle but, as can be simply demonstrated, also on the day-to-day variability and spatial distribution of coronal intensity that is determined by solar surface magnetic fields, including the locations of coronal holes that are the sources of high-speed solar wind causing geomagnetic storms. The latter were very similar for the eclipses in 1932, 1994, and 2017, which is the main reason why the naked-eye observations, as well as the processed images (1994 and 2017), of the white-light corona displayed very similar shapes. White-light corona image processing is a useful technique to enhance the contrast to observe fine-scale structure that is consistent with the physics of the solar atmosphere shaped by the magnetic field drawn out into the interplanetary space by solar wind.

Tectopontine pathway in the cat: laminar distribution of cells of origin and visual properties of target cells in dorsolateral pontine nucleus

1979 ◽  
Vol 42 (1) ◽  
pp. 1-15 ◽  
Author(s):  
G. Mower ◽  
A. Gibson ◽  
M. Glickstein
Keyword(s):  
Superior Colliculus ◽  
Visual Stimulation ◽  
Receptive Fields ◽  
Target Cells ◽  
Pontine Nucleus ◽  
Single Spot ◽  
Visual Cells ◽  
Visual Hemifield ◽  
Wide Range ◽  
Dorsolateral Pontine Nucleus

1. The superior colliculus projects to the dorsolateral nucleus of the pons. Retrograde transport of horseradish peroxidase (HRP) revealed that cells in the superior colliculus, which send their axons to the pons, lie in both superficial (III) and deep (IV--VII) layers. Superficial cells outnumbered deep cells. The inferior colliculus also projects heavily to the dorsolateral pontine nucleus. 2. Dorsolateral pontine visual cells were activated only by visual stimulation. Cells responsive to somatic or auditory stimulation were also found in the dorsolateral nucleus, and they too responded to only one sense modality. 3. Of the dorsolateral pontine visual cells, 69% were directionally selective. 4. Dorsolateral pontine visual cells were responsive to moving targets over a wide range of stimulus velocities. Velocities between 25 and 100 degrees/s were the most effective. No cells responded to a stationary stimulus. 5. Single-spot targets were the most effective stimuli. Stimulus size was a more important parameter than stimulus configuration. Many cells had inhibitory regions outside of their excitatory fields. 6. The excitatory receptive fields of dorsolateral pontine cells were very large (median, 1,100 deg2). 7. Nearly all receptive fields were centered in the contralateral visual hemifield, and 91% of the dorsolateral visual cells were activated from either eye. 8. We conclude that the visual cells in the dorsolateral nucleus have receptive-field properties that are similar to those of cells in the superior colliculus. The preference of dorsolateral cells for single-spot targets contrasts strongly with the multiple-spot preference of medial pontine cells, which receive their input from visual cortex.

scholarly journals Light adaptation alters inner retinal inhibition to shape OFF retinal pathway signaling

2016 ◽  
Vol 115 (6) ◽  
pp. 2761-2778 ◽  
Author(s):  
Reece E. Mazade ◽  
Erika D. Eggers
Keyword(s):  
Ganglion Cell ◽  
Bipolar Cell ◽  
Light Adaptation ◽  
Ganglion Cells ◽  
Receptive Fields ◽  
Excitatory Input ◽  
Bipolar Cells ◽  
Visual Sensitivity ◽  
Resting Membrane Potential ◽  
Wide Range

The retina adjusts its signaling gain over a wide range of light levels. A functional result of this is increased visual acuity at brighter luminance levels (light adaptation) due to shifts in the excitatory center-inhibitory surround receptive field parameters of ganglion cells that increases their sensitivity to smaller light stimuli. Recent work supports the idea that changes in ganglion cell spatial sensitivity with background luminance are due in part to inner retinal mechanisms, possibly including modulation of inhibition onto bipolar cells. To determine how the receptive fields of OFF cone bipolar cells may contribute to changes in ganglion cell resolution, the spatial extent and magnitude of inhibitory and excitatory inputs were measured from OFF bipolar cells under dark- and light-adapted conditions. There was no change in the OFF bipolar cell excitatory input with light adaptation; however, the spatial distributions of inhibitory inputs, including both glycinergic and GABAergic sources, became significantly narrower, smaller, and more transient. The magnitude and size of the OFF bipolar cell center-surround receptive fields as well as light-adapted changes in resting membrane potential were incorporated into a spatial model of OFF bipolar cell output to the downstream ganglion cells, which predicted an increase in signal output strength with light adaptation. We show a prominent role for inner retinal spatial signals in modulating the modeled strength of bipolar cell output to potentially play a role in ganglion cell visual sensitivity and acuity.

Sign in / Sign up

Export Citation Format

Share Document