Cross-Orientation Suppression: Monoptic and Dichoptic Mechanisms Are Different

2005 ◽  
Vol 94 (2) ◽  
pp. 1645-1650 ◽  
Author(s):  
Baowang Li ◽  
Matthew R. Peterson ◽  
Jeffrey K. Thompson ◽  
Thang Duong ◽  
Ralph D. Freeman
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Intracortical Inhibition ◽  
A Cell

The response of a cell in the primary visual cortex to an optimally oriented grating is suppressed by a superimposed orthogonal grating. This cross-orientation suppression (COS) is exhibited when the orthogonal and optimal stimuli are presented to the same eye (monoptically) or to different eyes (dichoptically). A recent study suggested that monoptic COS arises from subcortical processes; however, the mechanisms underlying dichoptic COS were not addressed. We have compared the temporal frequency tuning and stimulus adaptation properties of monoptic and dichoptic COS. We found that dichoptic COS is best elicited with lower temporal frequencies and is substantially reduced after prolonged adaptation to a mask grating. In contrast, monoptic COS is more pronounced with mask gratings at much higher temporal frequencies and is less prone to stimulus adaptation. These results suggest that monoptic COS is mediated by subcortical mechanisms, whereas intracortical inhibition is the mechanism for dichoptic COS.

A model for the estimate of local image velocity by cells in the visual cortex

1990 ◽  
Vol 239 (1295) ◽  
pp. 129-161 ◽  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Spatial Integration ◽  
Temporal Area ◽  
Image Velocity ◽  
Tuning Curves ◽  
Spatio Temporal ◽  
Local Image

Some computational theories of motion perception assume that the first stage en route to this perception is the local estimate of image velocity. However, this assumption is not supported by data from the primary visual cortex. Its motion sensitive cells are not selective to velocity, but rather are directionally selective and tuned to spatio-temporal frequen­cies. Accordingly, physiologically based theories start with filters selec­tive to oriented spatio-temporal frequencies. This paper shows that computational and physiological theories do not necessarily conflict, because such filters may, as a population, compute velocity locally. To prove this point, we show how to combine the outputs of a class of frequency tuned filters to detect local image velocity. Furthermore, we show that the combination of filters may simulate ‘Pattern’ cells in the middle temporal area (MT), whereas each filter simulates primary visual cortex cells. These simulations include three properties of the primary cortex. First, the spatio-temporal frequency tuning curves of the in­dividual filters display approximate space-time separability. Secondly, their direction-of-motion tuning curves depend on the distribution of orientations of the components of the Fourier decomposition and speed of the stimulus. Thirdly, the filters show facilitation and suppression for responses to apparent motions in the preferred and null directions, respect­ively. It is suggested that the MT’s role is not to solve the aperture problem, but to estimate velocities from primary cortex information. The spatial integration that accounts for motion coherence may be postponed to a later cortical stage.

scholarly journals Influence of Contrast on Orientation and Temporal Frequency Tuning in Ferret Primary Visual Cortex

2004 ◽  
Vol 91 (6) ◽  
pp. 2797-2808 ◽  
Author(s):  
Henry J. Alitto ◽  
W. Martin Usrey
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Orientation Tuning ◽  
Visual Response ◽  
Stimulus Contrast ◽  
Tuning Curves ◽  
Simple And Complex Cells

Neurons in primary visual cortex are highly sensitive to the contrast, orientation, and temporal frequency of a visual stimulus. These three stimulus properties can be varied independently of one another, raising the question of how they interact to influence neuronal responses. We recorded from individual neurons in ferret primary visual cortex to determine the influence of stimulus contrast on orientation tuning, temporal-frequency tuning, and latency to visual response. Results show that orientation-tuning bandwidth is not affected by contrast level. Thus neurons in ferret visual cortex display contrast-invariant orientation tuning. Stimulus contrast does, however, influence the structure of orientation-tuning curves as measures of circular variance vary inversely with contrast for both simple and complex cells. This change in circular variance depends, in part, on a contrast-dependent change in the ratio of null to preferred orientation responses. Stimulus contrast also has an influence on the temporal-frequency tuning of cortical neurons. Both simple and complex cells display a contrast-dependent rightward shift in their temporal frequency-tuning curves that results in an increase in the highest temporal frequency needed to produce a half-maximum response (TF50). Results show that the degree of the contrast-dependent increase in TF50 is similar for cortical neurons and neurons in the lateral geniculate nucleus (LGN) and indicate that subcortical mechanisms likely play a major role in establishing the degree of effect displayed by downstream neurons. Finally, results show that LGN and cortical neurons experience a contrast-dependent phase advance in their visual response. This phase advance is most pronounced for cortical neurons indicating a role for both subcortical and cortical mechanisms.

Cortical Maps of Separable Tuning Properties Predict Population Responses to Complex Visual Stimuli

2005 ◽  
Vol 94 (1) ◽  
pp. 775-787 ◽  
Author(s):  
Tanya I. Baker ◽  
Naoum P. Issa
Keyword(s):  
Visual Cortex ◽  
Spatial Frequency ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Sinusoidal Grating ◽  
Cortical Organization ◽  
Moving Images ◽  
Spatial Parameters

In the earliest cortical stages of visual processing, a scene is represented in different functional domains selective for specific features. Maps of orientation and spatial frequency preference have been described in the primary visual cortex using simple sinusoidal grating stimuli. However, recent imaging experiments suggest that the maps of these two spatial parameters are not sufficient to describe patterns of activity in different orientation domains generated in response to complex, moving stimuli. A model of cortical organization is presented in which cortical temporal frequency tuning is superimposed on the maps of orientation and spatial frequency tuning. The maps of these three tuning properties are sufficient to describe the activity in orientation domains that have been measured in response to drifting complex images. The model also makes specific predictions about how moving images are represented in different spatial frequency domains. These results suggest that the tangential organization of primary visual cortex can be described by a set of maps of separable neuronal receptive field features including maps of orientation, spatial frequency, and temporal frequency tuning properties.

scholarly journals Orientation Tuning, But Not Direction Selectivity, Is Invariant to Temporal Frequency in Primary Visual Cortex

2005 ◽  
Vol 94 (2) ◽  
pp. 1336-1345 ◽  
Author(s):  
Bartlett D. Moore ◽  
Henry J. Alitto ◽  
W. Martin Usrey
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Stimulus ◽  
Visual Processing ◽  
Cortical Neurons ◽  
Temporal Frequency ◽  
Direction Selectivity ◽  
Orientation Tuning ◽  
Orientation Contrast ◽  
Wide Range

The activity of neurons in primary visual cortex is influenced by the orientation, contrast, and temporal frequency of a visual stimulus. This raises the question of how these stimulus properties interact to shape neuronal responses. While past studies have shown that the bandwidth of orientation tuning is invariant to stimulus contrast, the influence of temporal frequency on orientation-tuning bandwidth is unknown. Here, we investigate the influence of temporal frequency on orientation tuning and direction selectivity in area 17 of ferret visual cortex. For both simple cells and complex cells, measures of orientation-tuning bandwidth (half-width at half-maximum response) are ∼20–25° across a wide range of temporal frequencies. Thus cortical neurons display temporal-frequency invariant orientation tuning. In contrast, direction selectivity is typically reduced, and occasionally reverses, at nonpreferred temporal frequencies. These results show that the mechanisms contributing to the generation of orientation tuning and direction selectivity are differentially affected by the temporal frequency of a visual stimulus and support the notion that stability of orientation tuning is an important aspect of visual processing.

Broad-tuned chromatic inputs to color-selective neurons in the monkey visual cortex

1994 ◽  
Vol 72 (1) ◽  
pp. 163-168 ◽  
Author(s):  
H. Sato ◽  
N. Katsuyama ◽  
H. Tamura ◽  
Y. Hata ◽  
T. Tsumoto
Keyword(s):  
Visual Cortex ◽  
Receptor Antagonist ◽  
Cytochrome Oxidase ◽  
Primary Visual Cortex ◽  
Emission Spectra ◽  
Intracortical Inhibition ◽  
Expected Value ◽  
Color Stimulus ◽  
Different Types ◽  
Monkey Visual Cortex

1. Input mechanisms of 21 color-selective cells in cytochrome oxidase-rich blobs in layer II/III of the anesthetized and paralyzed monkey primary visual cortex were studied by an iontophoretic administration of the GABAergic receptor antagonist bicuculline methiodide (BMI). 2. Color-selective blob cells become responsive to originally nonresponsive colors of stimuli or brightness contrast stimuli during removal of intracortical inhibition. 3. The magnitudes of the cells' responses to color stimuli during BMI administration were larger than the expected value of response calculated from the previously reported color tuning of color-selective geniculate cells and emission spectra of color stimulus. 4. These results suggest that color-selective blob cells receive a convergence of different types of chromatic inputs and that intracortical inhibition confers selectivity for a given color on them.

Mechanisms underlying direction selectivity of neurons in the primary visual cortex of the macaque

1995 ◽  
Vol 74 (4) ◽  
pp. 1382-1394 ◽  
Author(s):  
H. Sato ◽  
N. Katsuyama ◽  
H. Tamura ◽  
Y. Hata ◽  
T. Tsumoto
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Threshold Level ◽  
Intracortical Inhibition ◽  
Direction Selectivity ◽  
Gamma Aminobutyric Acid ◽  
Visual Responses ◽  
Preferred Direction ◽  
Control Response ◽  
Layer Vi

1. We studied the effects of blocking intracortical inhibition by microiontophoretic administration of bicuculline methiodide (BMI), a selective antagonist for gamma-aminobutyric acid-A receptors, on direction sensitivity of 103 neurons in the primary visual cortex (VI) of anesthetized and paralyzed monkeys. 2. The direction selectivity index (DSI) of each cell was calculated for the control response and response during the BMI administration at the optimal stimulus orientation to assess the directionality of an individual cell. 3. The averaged direction tuning of visual responses of cells was sharp in layers IVa and IVb, moderate in both interblob and blob regions of layer II/III and layers V and VI, and poor in layers IVc alpha and IVc beta. 4. Iontophoretic administration of BMI uncovered or facilitated responses to stimuli moving in the nonpreferred direction, and reduced DSIs of cells to a varying extent in all the layers except layer VI. Responses to stimuli moving in the preferred direction were also facilitated so that a slight bias of response toward the originally preferred direction remained during BMI administration in most cells. 5. Most of the cells in layers II/III (both blobs and interblobs) and IVb that receive inputs from layers IVc alpha and IVc beta showed a clear reduction of direction selectivity during BMI administration. This result suggests that intracortical inhibition plays an important role in the elaboration of direction selectivity at the second stage of information processing in VI. 6. The direction selectivity of cells in layer VI was most resistant to the effects of BMI, suggesting that it is dependent on excitatory inputs that are already direction selective, even though the sample size of this layer was small. 7. In direction-selective cells outside layer VI, responses to a stimulus moving in the preferred direction were enhanced in a way that was linearly related with those in the nonpreferred direction as the BMI dose was increased. This suggests that various amounts of inhibition interact linearly with directionally biased excitatory inputs to raise the firing threshold to various levels so as to produce various degrees of directionality. 8. These results suggest that, in most of the directionally sensitive cells except for those in layer VI, there are excitatory inputs which are bidirectional but slightly biased to one direction, and that the intracortical inhibition raises a threshold level of responses to excitatory inputs so that the response become direction selective.

Temporal-frequency tuning of direction selectivity in cat visual cortex

1992 ◽  
Vol 8 (4) ◽  
pp. 365-372 ◽  
Author(s):  
Alan B. Saul ◽  
Allen L. Humphrey
Keyword(s):  
Visual Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Direction Selectivity ◽  
Half Cycle ◽  
Low Frequencies ◽  
Preferred Direction ◽  
Cat Visual Cortex ◽  
Cortical Responses ◽  
Areas 17 And 18

AbstractResponses of 71 cells in areas 17 and 18 of the cat visual cortex were recorded extracellularly while stimulating with gratings drifting in each direction across the receptive field at a series of temporal frequencies. Direction selectivity was most prominent at temporal frequencies of 1–2 Hz. In about 20% of the total population, the response in the nonpreferred direction increased at temporal frequencies of around 4 Hz and direction selectivity was diminished or lost. In a few cells the preferred direction reversed.One consequence of this behavior was a tendency for the preferred direction to have lower optimal temporal frequencies than the nonpreferred direction. Across the population, the preferred direction was tuned almost an octave lower. In spite of this, temporal resolution was similar in the two directions. It appeared that responses in the nonpreferred direction were suppressed at low frequencies, then recovered at higher frequencies.This phenomenon might reflect the convergence in visual cortex of lagged and nonlagged inputs from the lateral geniculate nucleus. These afferents fire about a quarter-cycle apart (i.e. are in temporal quadrature) at low temporal frequencies, but their phase difference increases to a half-cycle by about 4 Hz. Such timing differences could underlie the prevalence of direction-selective cortical responses at 1 and 2 Hz and the loss of direction selectivity in many cells by 4 or 8 Hz.

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

1989 ◽  
Vol 2 (6) ◽  
pp. 609-620 ◽  
Author(s):  
A. B. Saul ◽  
M. S. Cynader
Keyword(s):  
Frequency Tuning ◽  
Temporal Frequency ◽  
Direction Selectivity ◽  
Cortical Cells ◽  
Specific Effects ◽  
A Cell ◽  
Visual Cortical ◽  
Velocity Matching ◽  
Induced Changes ◽  
Direction Opposite

AbstractAdaptation-induced changes in the temporal-frequency tuning and direction selectivity of cat visual cortical cells were studied. Aftereffects were induced largely independent of direction. Adapting in either direction reduced responses in both directions. Aftereffects in the direction opposite that adapted were only slightly weaker than were aftereffects in the adapted direction. No cell showed any enhancement of responses to drifting test stimuli after adapting with moving gratings. Adapting in a cell's null direction usually had no effect. Dramatic differences between the adaptation characteristics of moving and stationary stimuli were observed, however.Furthermore, aftereffects were temporal frequency specific. Temporal frequency-specific aftereffects were found in both directions: adapting in one direction induced frequency-specific effects in both directions. This bidirectionality of frequency-specific aftereffects applied to the spatial domain as well. Often, aftereffects in the direction opposite that adapted were more narrowly tuned.In general, adaptation could shift a cell's preferred temporal frequency. Aftereffects were most prominent at high temporal frequencies when testing in the adapted direction. Aftereffects seemed to be more closely linked to temporal frequency than to velocity matching.These results constrain models of cortical connectivity. In particular, we argue against schemes by which direction selectivity is generated by inhibiting a cell specifically when stimulated in the nonpreferred direction. Instead, we argue that cells receive bidirectional spatially and temporally tuned inputs, which could combine in spatiotemporal quadrature to produce direction selectivity.

Laminar Organization of Response Properties in Primary Visual Cortex of the Gray Squirrel(Sciurus carolinensis)

2005 ◽  
Vol 94 (5) ◽  
pp. 3538-3554 ◽  
Author(s):  
J. Alexander Heimel ◽  
Stephen D. Van Hooser ◽  
Sacha B. Nelson
Keyword(s):  
Visual Cortex ◽  
Spatial Frequency ◽  
Spontaneous Activity ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Sciurus Carolinensis ◽  
Gray Squirrel ◽  
Laminar Organization ◽  
Spatial Frequency Tuning ◽  
Layer 4

The gray squirrel ( Sciurus carolinensis) is a diurnal highly visual rodent with a cone-rich retina. To determine which features of visual cortex are common to highly visual mammals and which are restricted to non-rodent species, we studied the laminar organization of response properties in primary visual area V1 of isoflurane-anesthetized squirrels using extra-cellular single-unit recording and sinusoidal grating stimuli. Of the responsive cells, 75% were tuned for orientation. Only 10% were directionally selective, almost all in layer 6, a layer receiving direct input from the dorsal lateral geniculate nucleus (LGN). Cone opponency was widespread but almost absent from layer 6. Median optimal spatial frequency tuning was 0.21 cycles/°. Median optimal temporal frequency a high 5.3 Hz. Layer 4 had the highest percentage of simple cells and shortest latency (26 ms). Layers 2/3 had the lowest spontaneous activity and highest temporal frequency tuning. Layer 5 had the broadest spatial frequency tuning and most spontaneous activity. At the layer 4/5 border were sustained cells with high cone opponency. Simple cells, determined by modulation to drifting sinusoidal gratings, responded with shorter latencies, were more selective for orientation and direction, and were tuned to lower spatial frequencies. A comparison with other mammals shows that although the laminar organization of orientation selectivity is variable, the cortical input layers contain more linear cells in most mammals. Nocturnal mammals appear to have more orientation-selective neurons in V1 than diurnal mammals of similar size.

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