scholarly journals Awareness-dependent normalization framework of visual bottom-up attention

2021 ◽  
Author(s):  
Shiyu Wang ◽  
Ling Huang ◽  
Qinglin Chen ◽  
Jingyi Wang ◽  
Siting Xu ◽  
...  
Keyword(s):  
Stimulus Size ◽  
Response Functions ◽  
Backward Masking ◽  
Stimulus Contrast ◽  
Bottom Up ◽  
Contrast Gain ◽  
Cueing Effect ◽  
Cueing Task ◽  
Neural Computations ◽  
Contrast Response

Although bottom-up attention can improve visual performance with and without awareness, whether they are governed by a common neural computation remains unclear. Using a modified Posner paradigm with backward masking, we found that both the attention-triggered cueing effect with and without awareness displayed a monotonic gradient profile (Gaussian-like). The scope of this profile, however, was significantly wider with than without awareness. Subsequently, for each subject, the stimulus size was manipulated as their respective mean scopes with and without awareness while stimulus contrast was varied in a spatial cueing task. By measuring the gain pattern of contrast-response functions, we observed changes in the cueing effect consonant with changes in contrast gain for bottom-up attention with awareness and response gain for bottom-up attention without awareness. Our findings indicate an awareness-dependent normalization framework of visual bottom-up attention, placing a necessary constraint, namely, awareness, on our understanding of the neural computations underlying visual attention.

Contrast and Temporal Frequency-Related Adaptation in the Pretectal Nucleus of the Optic Tract

2005 ◽  
Vol 94 (1) ◽  
pp. 136-146 ◽  
Author(s):  
M. R. Ibbotson
Keyword(s):  
Visual Cortex ◽  
Optic Tract ◽  
Gain Control ◽  
Response Functions ◽  
High Contrast ◽  
Motion Adaptation ◽  
Contrast Gain ◽  
Contrast Gain Control ◽  
Contrast Adaptation ◽  
Contrast Response

In mammals, many cells in the retino-geniculate-cortical pathway adapt during stimulation with high contrast gratings. In the visual cortex, adaptation to high contrast images reduces sensitivity at low contrasts while only moderately affecting sensitivity at high contrasts, thus generating rightward shifts in the contrast response functions (contrast gain control). Similarly, motion adaptation at particular temporal frequencies (TFs) alters the temporal tuning properties of cortical cells. For the first time in any species, this paper investigates the influence of motion adaptation on both the contrast and TF responses of neurons in the retino-pretectal pathway by recording from direction-selective neurons in the nucleus of the optic tract (NOT) of the marsupial wallaby, Macropus eugenii. This species is of interest because its NOT receives almost all input directly from the retina, with virtually none from the visual cortex (unlike cats and primates). All NOT cells show changes in their contrast response functions after adaptation, many revealing contrast gain control. Contrast adaptation is direction-dependent, preferred directions producing the largest changes. The lack of cortical input suggests that contrast adaptation is generated independently from the cortex in the NOT or retina. Motion adaptation also produces direction-selective effects on the TF tuning of NOT neurons by shifting the location of the optimum TF. Cells that show strong adaptation to contrast also tend to show large changes in TF tuning, suggesting similar intracellular mechanisms. The data are discussed in terms of the generality of contrast adaptation across mammalian species and across unconnected brain regions within the same species.

Contrast gain control in the cat's visual system

1985 ◽  
Vol 54 (3) ◽  
pp. 651-667 ◽  
Author(s):  
I. Ohzawa ◽  
G. Sclar ◽  
R. D. Freeman
Keyword(s):  
Contrast Sensitivity ◽  
Cortical Neurons ◽  
Time Course ◽  
Gain Control ◽  
Local Contrast ◽  
Response Functions ◽  
Contrast Gain ◽  
Contrast Gain Control ◽  
Contrast Adaptation ◽  
Contrast Response

We have examined the idea that the adaptation of cortical neurons to local contrast levels in a visual stimulus is functionally advantageous. Specifically, cortical cells may have large differential contrast sensitivity as a result of adjustments that center a limited response range around a mean level of contrast. To evaluate this notion, we measured contrast-response functions of cells in striate cortex while systematically adapting them to different contrast levels of stimulus gratings. For the majority of cortical neurons tested, the results of this basic experiment show that contrast-response functions shift laterally along a log-contrast axis so that response functions match mean contrast levels in the stimulus. This implies a contrast-dependent change in the gain of the cell's contrast-response relationship. We define this process as contrast gain control. The degree to which this contrast adjustment occurs varies considerably from cell to cell. There are no obvious differences regarding cell type (simple vs. complex) or laminar distribution. Contrast gain control is almost certainly a cortical function, since lateral geniculate cells and fibers exhibit only minimal effects. Tests presented in the accompanying paper (37) provide additional evidence on the cortical origin of the process. In another series of experiments, the effect of contrast adaptation on physiological estimates of contrast sensitivity was evaluated. Sustained adaptation to contrast levels as low as 3% was capable of nearly doubling the thresholds of most of the cells tested. Adaptation may therefore be an important factor in determinations of the contrast sensitivity of cortical neurons. We tested the spatial extent of the mechanisms responsible for these gain-control effects by attempting to adapt cells using both a large grating and a grating patch limited to that portion of a cell's receptive field from which excitatory discharges could be elicited directly (the central discharge region). Adaptation was found to be an exclusive property of the central region. This held even in the case of hypercomplex cells, which received strong influences from surrounding regions of the visual field. Finally, we measured the time course of contrast adaptation. We found the process to be rather slow, with a mean time constant of approximately 6 s. Once again, there was considerable variability in this value from cell to cell.

Effect of stimulus contrast and size on NMDA receptor activity in cat lateral geniculate nucleus

1992 ◽  
Vol 68 (1) ◽  
pp. 182-196 ◽  
Author(s):  
Y. H. Kwon ◽  
S. B. Nelson ◽  
L. J. Toth ◽  
M. Sur
Keyword(s):  
Nmda Receptor ◽  
Stimulus Size ◽  
Optimal Size ◽  
Visual Response ◽  
Visual Responses ◽  
Stimulus Contrast ◽  
Surround Inhibition ◽  
X Cells ◽  
Contrast Response ◽  
Receptive Field Center

1. We studied the effect of varying excitatory and inhibitory drive on the N-methyl-D-aspartate (NMDA) receptor-mediated component of the visual responses of neurons in the cat dorsal lateral geniculate nucleus (dLGN) by varying the contrast and size of stimuli presented to the receptive fields of these cells. 2. Cells were classified as either on- or off-center, X or Y, and lagged or nonlagged. Stimulus contrast, and hence the amount of excitatory drive, was varied by changing the brightness of a spot, whose size and location matched the cell's receptive field center, relative to a fixed background luminance. Responses to varying contrast were collected from each cell before, during, and after iontophoretic application of D-2-amino-5-phosphonovaleric acid (D-APV), a specific NMDA receptor antagonist. From each contrast-response plot, a sigmoidal curve fit yielded five parameters on which we examined the effect of D-APV: the threshold contrast, saturation contrast, contrast at half saturation (C50), slope (gain) at C50, and saturation response. 3. In most cells, application of D-APV reduced both the saturation response and the gain of the contrast-response curve, but did not reduce or change significantly the threshold contrast, saturation contrast, or C50. 4. Cells varied in their sensitivity to D-APV, but for any given cell, the D-APV-sensitive component was nearly always a linear function of the control visual response level. Thus, for a spot of optimal size, there was a constant proportion of the visual response attributable to NMDA receptors, regardless of the amplitude of the response. 5. When the effect of D-APV on the visual responses to an optimal spot at varying contrasts was compared among different classes of dLGN cells, the visual responses of lagged X cells were reduced to a greater extent than those of either nonlagged X cells or the combined population of nonlagged X and Y cells. 6. Stimulus size (spot diameter) was also varied systematically at a fixed contrast to vary the inhibitory drive to dLGN cells. As stimulus size was increased, the response first increased because of increased stimulation of the receptive field center and then decreased because of increasing amounts of surround inhibition. 7. The D-APV-sensitive component of individual cell responses was greater when the stimulus spot was less than or equal to optimal size than when the spot was larger. Thus the contribution of NMDA receptors to the visual response decreased with increasing surround inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Contrast gain control in the kitten's visual system

1985 ◽  
Vol 54 (3) ◽  
pp. 668-675 ◽  
Author(s):  
G. Sclar ◽  
I. Ohzawa ◽  
R. D. Freeman
Keyword(s):  
Gain Control ◽  
Sine Wave ◽  
Response Functions ◽  
Cortical Cells ◽  
Contrast Gain ◽  
Contrast Gain Control ◽  
Response Range ◽  
Adult Cats ◽  
Contrast Response ◽  
Different Levels

We have studied the effects of contrast adaptation on cortical cells from 4- and 6-wk-old kittens (49 and 47 cells, respectively) using sine-wave grating stimuli. We wished to know if the effects of adaptation to different contrast levels are more extensive than those in adult animals. Our experiments involved adapting cells to different contrasts (3.1, 12.5, and 50%) while concurrently measuring their contrast-response functions at each of these different levels. We found qualitatively that the effects of adaptation in the kitten are similar to those we have previously documented in adult animals (19). Contrast-response functions are laterally shifted along the log-contrast axis, effectively matching the response range of the cells to prevailing contrast levels. The degree to which this occurred varied from cell to cell. The average degree to which cells showed these effects, as assessed both qualitatively and quantitatively, was greater for kittens than for adult cats, and greater for 4-wk-old kittens than for those aged 6 wk. This suggests that susceptibility to adaptation varies as a function of age. Additional studies were undertaken with the intent of localizing these adaptive effects. First, lateral geniculate cells and fibers (n = 23) were studied with our standard protocol, and second, we investigated the degree to which the effects of adaptation of cortical cells transferred interocularly.(ABSTRACT TRUNCATED AT 250 WORDS)

Contrast response of temporally sparse dichoptic multifocal visual evoked potentials

2005 ◽  
Vol 22 (2) ◽  
pp. 153-162 ◽  
Author(s):  
TED MADDESS ◽  
ANDREW CHARLES JAMES ◽  
ELIZABETH ANNE BOWMAN
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Human Subjects ◽  
Response Functions ◽  
Signal To Noise ◽  
Recording Time ◽  
Contrast Gain ◽  
Multifocal Visual Evoked Potentials ◽  
Contrast Response ◽  
Visual Evoked

Temporally sparse stimuli have been found to produce larger multifocal visual evoked potentials than rapid contrast-reversal stimuli. We compared the contrast-response functions of conventional contrast-reversing (CR) stimuli and three grades of temporally sparse stimuli, examining both the changes in response amplitude and signal-to-noise ratio (SNR). All stimuli were presented dichoptically to normal adult human subjects. One stimulus variant, the slowest pattern pulse, had interleaved monocular and binocular stimuli. Response amplitudes and SNRs were similar for all stimuli at contrast 0.4 but grew faster with increasing contrast for the sparser stimuli. The best sparse stimulus provided an SNR improvement that corresponded to a recording time improvement of 2.6 times relative to that required for contrast reversing stimuli. Multiple regression of log-transformed response metrics characterized the contrast-response functions by fitting power-law relationships. The exponents for the two sparsest stimuli were significantly larger (P < 0.001) than for the CR stimuli, as were the mean response amplitudes and signal-to-noise ratios for these stimuli. The contrast-dependent response enhancement is discussed with respect to the possible influences of rapid retinal contrast gain control, or intracortical and cortico-geniculate feedback.

scholarly journals Spectral properties and retinal distribution of ferret cones

2003 ◽  
Vol 20 (1) ◽  
pp. 11-17 ◽  
Author(s):  
JACK B. CALDERONE ◽  
GERALD H. JACOBS
Keyword(s):  
Spectral Properties ◽  
Response Functions ◽  
Gain Ratio ◽  
Contrast Gain ◽  
Flicker Erg ◽  
Adaptation State ◽  
Retinal Distribution ◽  
Antibody Labeling ◽  
Contrast Response ◽  
Relative Weighting

The spectral mechanisms of the ferret (Mustela putorious furo) were studied with electroretinogram (ERG) flicker photometry. Variations in adaptation state and flicker rate were used to define corneally based spectral sensitivities for the three classes of receptor present in the retina of this mustelid—rods (λmax = 505 nm), S cones (430 nm), and L cones (558 nm). The retinal distributions of the two classes of cone were determined using opsin antibody labeling. Ferret retinas contain a total of about 1.3 million cones with L cones outnumbering S cones in a ratio of approximately 14:1. ERGs were also recorded using 18.75-Hz flickering stimuli that were designed to isolate signals from individual cone classes. The contrast/response functions for signals originating from both S and L cones were linear over low-to-moderate levels of contrast, but with greatly different slopes for the two cone types. The L:S contrast gain ratio derived from a comparison of these slopes, as well as inferences drawn from another experiment in which responses to various combinations of L- and S-cone activation were analyzed, suggest that contributions of these two cone types to the flicker ERG have a relative weighting of about 4:1 to 5:1 (L/S).

Dynamic shifts of the contrast-response function

1997 ◽  
Vol 14 (3) ◽  
pp. 577-587 ◽  
Author(s):  
Jonathan D. Victor ◽  
Mary M. Conte ◽  
Keith P. Purpura
Keyword(s):  
Gain Control ◽  
Human Vision ◽  
High Contrast ◽  
Contrast Level ◽  
Low Contrast ◽  
Contrast Gain ◽  
Contrast Response Function ◽  
Stimuli Response ◽  
Response Phase ◽  
Contrast Response

AbstractWe recorded visual evoked potentials in response to square-wave contrast-reversal checkerboards undergoing a transition in the mean contrast level. Checkerboards were modulated at 4.22 Hz (8.45-Hz reversal rate). After each set of 16 cycles of reversals, stimulus contrast abruptly switched between a “high” contrast level (0.06 to 1.0) to a “low” contrast level (0.03 to 0.5). Higher contrasts attenuated responses to lower contrasts by up to a factor of 2 during the period immediately following the contrast change. Contrast-response functions derived from the initial second following a conditioning contrast shifted by a factor of 2–4 along the contrast axis. For low-contrast stimuli, response phase was an advancing function of the contrast level in the immediately preceding second. For high-contrast stimuli, response phase was independent of the prior contrast history. Steady stimulation for periods as long as 1 min produced only minor effects on response amplitude, and no detectable effects on response phase. These observations delineate the dynamics of a contrast gain control in human vision.

scholarly journals Contrast response functions in the visual wulst of the alert burrowing owl: a single-unit study

2016 ◽  
Vol 116 (4) ◽  
pp. 1765-1784 ◽  
Author(s):  
Pedro Gabrielle Vieira ◽  
João Paulo Machado de Sousa ◽  
Jerome Baron
Keyword(s):  
Single Unit ◽  
Goodness Of Fit ◽  
Dynamic Range ◽  
Information Criterion ◽  
Future Research ◽  
Response Functions ◽  
Athene Cunicularia ◽  
Low Contrast ◽  
Burrowing Owl ◽  
Contrast Response

The neuronal representation of luminance contrast has not been thoroughly studied in birds. Here we present a detailed quantitative analysis of the contrast response of 120 individual neurons recorded from the visual wulst of awake burrowing owls ( Athene cunicularia). Stimuli were sine-wave gratings presented within the cell classical receptive field and optimized in terms of eye preference, direction of drift, and spatiotemporal frequency. As contrast intensity was increased from zero to near 100%, most cells exhibited a monotonic response profile with a compressive, at times saturating, nonlinearity at higher contrasts. However, contrast response functions were found to have a highly variable shape across cells. With the view to capture a systematic trend in the data, we assessed the performance of four plausible models (linear, power, logarithmic, and hyperbolic ratio) using classical goodness-of-fit measures and more rigorous statistical tools for multimodel inferences based on the Akaike information criterion. From this analysis, we conclude that a high degree of model uncertainty is present in our data, meaning that no single descriptor is able on its own to capture the heterogeneous nature of single-unit contrast responses in the wulst. We further show that the generalizability of the hyperbolic ratio model established, for example, in the primary visual cortex of cats and monkeys is not tenable in the owl wulst mainly because most neurons in this area have a much wider dynamic range that starts at low contrast. The challenge for future research will be to understand the functional implications of these findings.

Contrast encoding in retinal bipolar cells: Current vs. voltage

2003 ◽  
Vol 20 (1) ◽  
pp. 19-28 ◽  
Author(s):  
WALLACE B. THORESON ◽  
DWIGHT A. BURKHARDT
Keyword(s):  
Dynamic Range ◽  
Linear Regression Analysis ◽  
Bipolar Cells ◽  
Response Analysis ◽  
Voltage Response ◽  
Cone Voltage ◽  
Current Response ◽  
Contrast Gain ◽  
Retinal Bipolar Cells ◽  
Contrast Response

To investigate the influence of voltage-sensitive conductances in shaping light-evoked responses of retinal bipolar cells, whole-cell recordings were made in the slice preparation of the tiger salamander, Ambystoma tigrinum. To study contrast encoding, the retina was stimulated with 0.5-s steps of negative and positive contrasts of variable magnitude. In the main, responses recorded under voltage- and current-clamp modes were remarkably similar. In general agreement with past results in the intact retina, the contrast/response curves were relatively steep for small contrasts, thus showing high contrast gain; the dynamic range was narrow, and responses tended to saturate at relatively small contrasts. For ON and OFF cells, linear regression analysis showed that the current response accounted for 83–93% of the variance of the voltage response. Analysis of specific parameters of the contrast/response curve showed that contrast gain was marginally higher for voltage than current in three of four cases, while no significant differences were found for half-maximal contrast (C50), dynamic range, or contrast dominance. In sum, the overall similarity between current and voltage responses indicates that voltage-sensitive conductances do not play a major role in determining the shape of the bipolar cell's contrast response in the light-adapted retina. The salient characteristics of the contrast response of bipolars apparently arise between the level of the cone voltage response and the postsynaptic current of bipolar cells, via the transformation between cone voltage and transmitter release and/or via the interaction between the neurotransmitter glutamate and its postsynaptic receptors on bipolar cells.

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