Noisy Template Matching: A Model for Detection and Discrimination

The detection and discrimination of simple patterns occupies a central place in visual psychophysics. A wide variety of phenomena have been observed in this paradigm, such as: Weber's law; masking (simultaneous, forward, and backward); masking by noise; spatial frequency tuning; orientation tuning; and area summation. We suggest that many of these phenomena can be explained by a simple model which we call ‘noisy template matching’. In this model, the encoded stimulus is matched to a memorised template. Both stimulus and template are corrupted by additive noise. The template matching operation yields a decision variable, to which more noise is added. This model is very simple, but it has many interesting consequences. It provides qualitative explanations for many of the phenomena mentioned above, and with additional (but we think reasonable) assumptions about lens blur, contrast nonlinearity (Whittle, 1986 Vision Research26 1677 – 1691), uncertainty (Pelli, 1985 Journal of the Optical Society of America2 1508 – 1532), and suboptimal templates, the model also provides good quantitative accounts of these phenomena.

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Spatial-frequency and orientation tuning in psychophysical end-stopping

Visual Neuroscience ◽

10.1017/s0952523898154019 ◽

1998 ◽

Vol 15 (4) ◽

pp. 585-595 ◽

Cited By ~ 10

Author(s):

CONG YU ◽

DENNIS M. LEVI

Keyword(s):

Spatial Frequency ◽

Frequency Tuning ◽

Spatial Filter ◽

Orientation Tuning ◽

Maximal Strength ◽

Facilitation Effect ◽

Spatial Filters ◽

Spatial Frequency Tuning ◽

Spatial Frequencies ◽

Wide Range

A psychophysical analog to cortical receptive-field end-stopping has been demonstrated previously in spatial filters tuned to a wide range of spatial frequencies (Yu & Levi, 1997a). The current study investigated tuning characteristics in psychophysical spatial filter end-stopping. When a D6 (the sixth derivative of a Gaussian) target is masked by a center mask (placed in the putative spatial filter center), two end-zone masks (placed in the filter end-zones) reduce thresholds. This “end-stopping” effect (the reduction of masking induced by end-zone masks) was measured at various spatial frequencies and orientations of end-zone masks. End-stopping reached its maximal strength when the spatial frequency and/or orientation of the end-zone masks matched the spatial frequency and/or orientation of the target and center mask, showing spatial-frequency tuning and orientation tuning. The bandwidths of spatial-frequency and orientation tuning functions decreased with increasing target spatial frequency. At larger orientation differences, however, end-zone masks induced a secondary facilitation effect, which was maximal when the spatial frequency of end-zone masks equated the target spatial frequency. This facilitation effect might be related to certain types of contour and texture perception, such as perceptual pop-out.

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Neurons in cat V1 show significant clustering by degree of tuning

Journal of Neurophysiology ◽

10.1152/jn.00646.2014 ◽

2015 ◽

Vol 113 (7) ◽

pp. 2555-2581 ◽

Cited By ~ 4

Author(s):

Avi J. Ziskind ◽

Al A. Emondi ◽

Andrei V. Kurgansky ◽

Sergei P. Rebrik ◽

Kenneth D. Miller

Keyword(s):

Spatial Frequency ◽

Frequency Tuning ◽

Direction Selectivity ◽

Preferred Orientation ◽

Orientation Tuning ◽

Complex Cells ◽

Spatial Frequency Tuning ◽

Spatial Frequencies ◽

Tuning Width ◽

Simple And Complex Cells

Neighboring neurons in cat primary visual cortex (V1) have similar preferred orientation, direction, and spatial frequency. How diverse is their degree of tuning for these properties? To address this, we used single-tetrode recordings to simultaneously isolate multiple cells at single recording sites and record their responses to flashed and drifting gratings of multiple orientations, spatial frequencies, and, for drifting gratings, directions. Orientation tuning width, spatial frequency tuning width, and direction selectivity index (DSI) all showed significant clustering: pairs of neurons recorded at a single site were significantly more similar in each of these properties than pairs of neurons from different recording sites. The strength of the clustering was generally modest. The percent decrease in the median difference between pairs from the same site, relative to pairs from different sites, was as follows: for different measures of orientation tuning width, 29–35% (drifting gratings) or 15–25% (flashed gratings); for DSI, 24%; and for spatial frequency tuning width measured in octaves, 8% (drifting gratings). The clusterings of all of these measures were much weaker than for preferred orientation (68% decrease) but comparable to that seen for preferred spatial frequency in response to drifting gratings (26%). For the above properties, little difference in clustering was seen between simple and complex cells. In studies of spatial frequency tuning to flashed gratings, strong clustering was seen among simple-cell pairs for tuning width (70% decrease) and preferred frequency (71% decrease), whereas no clustering was seen for simple-complex or complex-complex cell pairs.

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A spherical model for orientation and spatial–frequency tuning in a cortical hypercolumn

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2002.1109 ◽

2002 ◽

Vol 358 (1438) ◽

pp. 1643-1667 ◽

Cited By ~ 32

Author(s):

Paul C. Bressloff ◽

Jack D. Cowan

Keyword(s):

Spatial Frequency ◽

Frequency Tuning ◽

Cortical Cell ◽

Faithful Representation ◽

Orientation Tuning ◽

Linear Filter ◽

Local Orientation ◽

Functional Interpretation ◽

Feed Forward ◽

Spatial Frequency Tuning

A theory is presented of the way in which the hypercolumns in primary visual cortex (V1) are organized to detect important features of visual images, namely local orientation and spatial–frequency. Given the existence in V1 of dual maps for these features, both organized around orientation pinwheels, we constructed a model of a hypercolumn in which orientation and spatial–frequency preferences are represented by the two angular coordinates of a sphere. The two poles of this sphere are taken to correspond, respectively, to high and low spatial–frequency preferences. In Part I of the paper, we use mean–field methods to derive exact solutions for localized activity states on the sphere. We show how cortical amplification through recurrent interactions generates a sharply tuned, contrast–invariant population response to both local orientation and local spatial frequency, even in the case of a weakly biased input from the lateral geniculate nucleus (LGN). A major prediction of our model is that this response is non–separable with respect to the local orientation and spatial frequency of a stimulus. That is, orientation tuning is weaker around the pinwheels, and there is a shift in spatial–frequency tuning towards that of the closest pinwheel at non–optimal orientations. In Part II of the paper, we demonstrate that a simple feed–forward model of spatial–frequency preference, unlike that for orientation preference, does not generate a faithful representation when amplified by recurrent interactions in V1. We then introduce the idea that cortico–geniculate feedback modulates LGN activity to generate a faithful representation, thus providing a new functional interpretation of the role of this feedback pathway. Using linear filter theory, we show that if the feedback from a cortical cell is taken to be approximately equal to the reciprocal of the corresponding feed–forward receptive field (in the two–dimensional Fourier domain), then the mismatch between the feed–forward and cortical frequency representations is eliminated. We therefore predict that cortico–geniculate feedback connections innervate the LGN in a pattern determined by the orientation and spatial–frequency biases of feed–forward receptive fields. Finally, we show how recurrent cortical interactions can generate cross–orientation suppression.

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Role of intrathalamic inhibition on the spatial frequency tuning of neurons in the lateral geniculate nucleus of the cat

Neuroscience Research ◽

10.1016/j.neures.2009.09.477 ◽

2009 ◽

Vol 65 ◽

pp. S106

Author(s):

Akihiro Kimura ◽

Satoshi Shimegi ◽

Shin-ichiro Hara ◽

Masahiro Okamoto ◽

Hiromichi Sato

Keyword(s):

Spatial Frequency ◽

Lateral Geniculate Nucleus ◽

Frequency Tuning ◽

Spatial Frequency Tuning ◽

Lateral Geniculate

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

Visual Neuroscience ◽

10.1017/s0952523800003527 ◽

1989 ◽

Vol 2 (6) ◽

pp. 593-607 ◽

Cited By ~ 65

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.

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Functional organization of spatial frequency tuning in macaque V1 revealed with two-photon calcium imaging

Progress in Neurobiology ◽

10.1016/j.pneurobio.2021.102120 ◽

2021 ◽

pp. 102120

Author(s):

Shu-Chen Guan ◽

Nian-Sheng Ju ◽

Louis Tao ◽

Shi-Ming Tang ◽

Cong Yu

Keyword(s):

Spatial Frequency ◽

Calcium Imaging ◽

Functional Organization ◽

Frequency Tuning ◽

Two Photon ◽

Spatial Frequency Tuning

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Receptive Field Size and Response Latency Are Correlated Within the Cat Visual Thalamus

Journal of Neurophysiology ◽

10.1152/jn.00847.2004 ◽

2005 ◽

Vol 93 (6) ◽

pp. 3537-3547 ◽

Cited By ~ 20

Author(s):

Chong Weng ◽

Chun-I Yeh ◽

Carl R. Stoelzel ◽

Jose-Manuel Alonso

Keyword(s):

Receptive Field ◽

Spatial Frequency ◽

Response Latency ◽

Time Course ◽

Frequency Tuning ◽

Receptive Fields ◽

Cortical Cell ◽

Field Size ◽

Receptive Field Size ◽

Spatial Frequency Tuning

Each point in visual space is encoded at the level of the thalamus by a group of neighboring cells with overlapping receptive fields. Here we show that the receptive fields of these cells differ in size and response latency but not at random. We have found that in the cat lateral geniculate nucleus (LGN) the receptive field size and response latency of neighboring neurons are significantly correlated: the larger the receptive field, the faster the response to visual stimuli. This correlation is widespread in LGN. It is found in groups of cells belonging to the same type (e.g., Y cells), and of different types (i.e., X and Y), within a specific layer or across different layers. These results indicate that the inputs from the multiple geniculate afferents that converge onto a cortical cell (approximately 30) are likely to arrive in a sequence determined by the receptive field size of the geniculate afferents. Recent studies have shown that the peak of the spatial frequency tuning of a cortical cell shifts toward higher frequencies as the response progresses in time. Our results are consistent with the idea that these shifts in spatial frequency tuning arise from differences in the response time course of the thalamic inputs.

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