scholarly journals How attention enhances spatial resolution: Evidence from selective adaptation to spatial frequency

2006 ◽  
Vol 68 (6) ◽  
pp. 1004-1012 ◽  
Author(s):  
Marisa Carrasco ◽  
Fani Loula ◽  
Yun-Xian Ho
Keyword(s):  
Spatial Frequency ◽  
Spatial Resolution ◽  
Selective Adaptation

Adaptation in single units in visual cortex: The tuning of aftereffects in the spatial domain

1989 ◽  
Vol 2 (6) ◽  
pp. 593-607 ◽  
Author(s):  
A. B. Saul ◽  
M. S. Cynader
Keyword(s):  
Spatial Frequency ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Cortical Cell ◽  
Selective Adaptation ◽  
Single Units ◽  
Spatial Frequency Tuning ◽  
Sinusoidal Gratings ◽  
A Cell ◽  
Drift Direction

AbstractCat striate cortical neurons were investigated using a new method of studying adaptation aftereffects. Stimuli were sinusoidal gratings of variable contrast, spatial frequency, and drift direction and rate. A series of alternating adapting and test trials was presented while recording from single units. Control trials were completely integrated with the adapted trials in these experiments.Every cortical cell tested showed selective adaptation aftereffects. Adapting at suprathreshold contrasts invariably reduced contrast sensitivity. Significant aftereffects could be observed even when adapting at low contrasts.The spatial-frequency tuning of aftereffects varied from cell to cell. Adapting at a given spatial frequency generally resulted in a broad response reduction at test frequencies above and below the adapting frequency. Many cells lost responses predominantly at frequencies lower than the adapting frequency.The tuning of aftereffects varied with the adapting frequency. In particular, the strongest aftereffects occurred near the adapting frequency. Adapting at frequencies just above the optimum for a cell often altered the spatial-frequency tuning by shifting the peak toward lower frequencies. The fact that the tuning of aftereffects did not simply match the tuning of the cell, but depended on the adapting stimulus, implies that extrinsic mechanisms are involved in adaptation effects.

Population Models, Not Analyses, of Human Neuroscience Measurements

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Justin L. Gardner ◽  
Elisha P. Merriam
Keyword(s):  
Spatial Frequency ◽  
Spatial Scale ◽  
Spatial Resolution ◽  
Population Models ◽  
Orientation Tuning ◽  
Computational Techniques ◽  
Publication Date ◽  
Vision Science ◽  
Orientation Information ◽  
Computational Analyses

Selectivity for many basic properties of visual stimuli, such as orientation, is thought to be organized at the scale of cortical columns, making it difficult or impossible to measure directly with noninvasive human neuroscience measurement. However, computational analyses of neuroimaging data have shown that selectivity for orientation can be recovered by considering the pattern of response across a region of cortex. This suggests that computational analyses can reveal representation encoded at a finer spatial scale than is implied by the spatial resolution limits of measurement techniques. This potentially opens up the possibility to study a much wider range of neural phenomena that are otherwise inaccessible through noninvasive measurement. However, as we review in this article, a large body of evidence suggests an alternative hypothesis to this superresolution account: that orientation information is available at the spatial scale of cortical maps and thus easily measurable at the spatial resolution of standard techniques. In fact, a population model shows that this orientation information need not even come from single-unit selectivity for orientation tuning, but instead can result from population selectivity for spatial frequency. Thus, a categorical error of interpretation can result whereby orientation selectivity can be confused with spatial frequency selectivity. This is similarly problematic for the interpretation of results from numerous studies of more complex representations and cognitive functions that have built upon the computational techniques used to reveal stimulus orientation. We suggest in this review that these interpretational ambiguities can be avoided by treating computational analyses as models of the neural processes that give rise to measurement. Building upon the modeling tradition in vision science using considerations of whether population models meet a set of core criteria is important for creating the foundation for a cumulative and replicable approach to making valid inferences from human neuroscience measurements. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Selective Adaptation to Low Spatial Frequencies Does Not Decrease the Mueller-Lyer Illusion

1994 ◽  
Vol 78 (1) ◽  
pp. 339-347
Author(s):  
Janet D. Larsen ◽  
Beth Anne Goldstein
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Major Part ◽  
Selective Adaptation ◽  
Sinusoidal Grating ◽  
Square Wave ◽  
Frequency Information ◽  
Lyer Illusion ◽  
Spatial Frequencies

The idea that low spatial-frequency information in the Mueller-Lyer figure accounts for a major part of the illusion was tested in a series of five studies. In Study 1, subjects were selectively adapted to high or low square-wave spatial-frequency gratings with no difference in the magnitude of illusion they experienced. Similarly, adaptation to sinusoidal grating patterns with either high or low spatial frequency had no effect on the magnitude of illusion experienced (Studies 2 to 5). The failure of adaptation to low spatial-frequency gratings to affect the magnitude of illusion experienced indicates either that the illusion cannot be accounted for by the low spatial-frequency information or that adaptation of the visual system by grating patterns cannot be used to explore any effects of the low spatial frequencies in the figure.

scholarly journals Attention Modifies Spatial Resolution According to Task Demands

2017 ◽  
Vol 28 (3) ◽  
pp. 285-296 ◽  
Author(s):  
Antoine Barbot ◽  
Marisa Carrasco
Keyword(s):  
Spatial Resolution ◽  
High Frequency ◽  
Selective Adaptation ◽  
Task Demands ◽  
Endogenous Attention ◽  
Voluntary Attention ◽  
Improve Performance ◽  
Low Frequencies ◽  
Spatial Frequencies ◽  
Flexible Mechanism

How does visual attention affect spatial resolution? In texture-segmentation tasks, exogenous (involuntary) attention automatically increases resolution at the attended location, which improves performance where resolution is too low (at the periphery) but impairs performance where resolution is already too high (at central locations). Conversely, endogenous (voluntary) attention improves performance at all eccentricities, which suggests a more flexible mechanism. Here, using selective adaptation to spatial frequency, we investigated the mechanism by which endogenous attention benefits performance in resolution tasks. Participants detected a texture target that could appear at several eccentricities. Adapting to high or low spatial frequencies selectively affected performance in a manner consistent with changes in resolution. Moreover, adapting to high, but not low, frequencies mitigated the attentional benefit at central locations where resolution was too high; this shows that attention can improve performance by decreasing resolution. Altogether, our results indicate that endogenous attention benefits performance by modulating the contribution of high-frequency information in order to flexibly adjust spatial resolution according to task demands.

scholarly journals Effect of Filtered Back-Projection Filters to Low-Contrast Object Imaging in Ultra-High-Resolution (UHR) Cone-Beam Computed Tomography (CBCT)

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6416
Author(s):  
Sunghoon Choi ◽  
Chang-Woo Seo ◽  
Bo Kyung Cha
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Spatial Frequency ◽  
Spatial Resolution ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Acquisition Time ◽  
Imaging Protocol ◽  
Low Contrast ◽  
Smoothing Window

In this study, the effect of filter schemes on several low-contrast materials was compared using standard and ultra-high-resolution (UHR) cone-beam computed tomography (CBCT) imaging. The performance of the UHR-CBCT was quantified by measuring the modulation transfer function (MTF) and the noise power spectrum (NPS). The MTF was measured at the radial location around the cylindrical phantom, whereas the NPS was measured in the eight different homogeneous regions of interest. Six different filter schemes were designed and implemented in the CT sinogram from each imaging configuration. The experimental results indicated that the filter with smaller smoothing window preserved the MTF up to the highest spatial frequency, but larger NPS. In addition, the UHR imaging protocol provided 1.77 times better spatial resolution than the standard acquisition by comparing the specific spatial frequency (f50) under the same conditions. The f50s with the flat-top window in UHR mode was 1.86, 0.94, 2.52, 2.05, and 1.86 lp/mm for Polyethylene (Material 1, M1), Polystyrene (M2), Nylon (M3), Acrylic (M4), and Polycarbonate (M5), respectively. The smoothing window in the UHR protocol showed a clearer performance in the MTF according to the low-contrast objects, showing agreement with the relative contrast of materials in order of M3, M4, M1, M5, and M2. In conclusion, although the UHR-CBCT showed the disadvantages of acquisition time and radiation dose, it could provide greater spatial resolution with smaller noise property compared to standard imaging; moreover, the optimal window function should be considered in advance for the best UHR performance.

Orientation Channels in the Peripheral Visual Field

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 362-362
Author(s):  
R J Snowden
Keyword(s):  
Spatial Frequency ◽  
Peripheral Vision ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
High Spatial Frequency ◽  
Selective Adaptation ◽  
Orientation Tuning ◽  
Peripheral Retina ◽  
Foveal Vision ◽  
Analysis Techniques

Peripheral vision has been modelled as a coarser version of foveal vision. Thus visual behaviour elicited by, say, a 2 cycles deg−1 grating imaged foveally would be reproduced in the periphery by a lower spatial frequency (say 1 cycle deg−1). Tuning for orientation is broader at a low than high spatial frequency (Snowden, 1992 Vision Research32 1965 – 1974). Taken together this leads to the surprising prediction that, given a particular spatial frequency, tuning for orientation is narrower for peripheral viewing! In this study it has also been found that orientation tuning broadens with increasing temporal frequency, but the opposite relationship has been reported for peripheral vision (Sharpe and Tolhurst, 1973 Vision Research13 2103 – 2112). Orientation bandwidths were measured by the method of selective adaptation following the procedures and analysis techniques described by Snowden (1991 Proceedings of the Royal Society of London, Series B246 53 – 59). The results show that orientation bandwidths did indeed narrow as a stimulus was imaged more peripherally, so that its bandwidth in the peripheral retina could be half that of the fovea. However, at a greater eccentricity, bandwidths broadened once more. The results were not influenced by the contrast of the adaptation pattern eliminating visibility as a possible explanation. Increasing temporal frequency broadened orientation bandwidth at all eccentricities.

Effects of Orientation-Selective Adaptation on the Zöllner Illusion

Perception ◽  
1987 ◽  
Vol 16 (4) ◽  
pp. 473-483 ◽  
Author(s):  
Kazunori Morikawa
Keyword(s):  
Spatial Frequency ◽  
Illusion Magnitude ◽  
Selective Adaptation ◽  
Tilt Aftereffect ◽  
Apparent Contrast ◽  
Inhibitory Interaction ◽  
Retinal Adaptation ◽  
Adaptation Effects

The model of inhibitory interaction between orientation detectors was examined by prolonged presentation of grating patterns (which was expected to induce orientation-selective adaptation) before measurement of the Zöllner illusion. Adaptation effects were measured under conditions which excluded intrusion by the tilt aftereffect. In experiment 1, illusion magnitude greatly decreased only when the orientation of the adapting grating was the same as that of the inducing lines, which confirmed the first prediction deduced from the model. There was no effect of adapting grating when it was oriented more than 20 ° away from the inducing lines. In experiment 2, adaptation effects were selective not only to orientation but also to spatial frequency. In experiment 3 it was shown that illusion reduction was mediated neither by lowered apparent contrast of the inducing lines nor by retinal adaptation. The results are discussed with respect to the nature of adaptation and possible physiological correlates.

scholarly journals One Blue Colour Channel or Two?

Perception ◽  
10.1068/p5165 ◽  
2005 ◽  
Vol 34 (8) ◽  
pp. 921-925 ◽  
Author(s):  
Alexander D Logvinenko ◽  
Sara J Hutchinson
Keyword(s):  
Spatial Frequency ◽  
Spatial Resolution ◽  
High Spatial Frequency ◽  
Human Vision ◽  
Frequency Resolution ◽  
Blue Colour ◽  
General Belief ◽  
Apparent Paradox ◽  
Spatial Sensitivity ◽  
Colour Channel

Contrary to the general belief that the yellow-blue mechanism has lower spatial resolution than the red-green mechanism, it has been recently claimed that both mechanisms have similar spatial sensitivity (McKeefry et al, 2001 Vision Research41 245–255). Studying high-spatial-frequency tritanopia (a colour illusion based on spatio-chromatic interactions in human vision), we found strong evidence for the existence of two blue mechanisms—with low and high spatial-frequency resolution. If confirmed, this may resolve the apparent paradox concerning spatial resolution of the yellow-blue mechanism.

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