scholarly journals The motion after-effect: local and global contributions to contrast sensitivity

2009 ◽  
Vol 276 (1662) ◽  
pp. 1545-1554 ◽  
Author(s):  
Karin Nordström ◽  
David C O'Carroll
Keyword(s):  
Noise Analysis ◽  
Motion Adaptation ◽  
Contrast Gain ◽  
Contrast Response Function ◽  
After Effect ◽  
Widespread Phenomenon ◽  
Motion Coding ◽  
Processing Techniques ◽  
Contrast Response ◽  
Peripheral Sensory

Motion adaptation is a widespread phenomenon analogous to peripheral sensory adaptation, presumed to play a role in matching responses to prevailing current stimulus parameters and thus to maximize efficiency of motion coding. While several components of motion adaptation (contrast gain reduction, output range reduction and motion after-effect) have been described, previous work is inconclusive as to whether these are separable phenomena and whether they are locally generated. We used intracellular recordings from single horizontal system neurons in the fly to test the effect of local adaptation on the full contrast-response function for stimuli at an unadapted location. We show that contrast gain and output range reductions are primarily local phenomena and are probably associated with spatially distinct synaptic changes, while the antagonistic after-potential operates globally by transferring to previously unadapted locations. Using noise analysis and signal processing techniques to remove ‘spikelets’, we also characterize a previously undescribed alternating current component of adaptation that can explain several phenomena observed in earlier studies.

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.

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.

scholarly journals Electrophysiological measures of visual suppression

2021 ◽  
Author(s):  
Daniel H Baker ◽  
Greta Vilidaite ◽  
Alex R Wade
Keyword(s):  
Response Function ◽  
Second Harmonic ◽  
Meta Analysis ◽  
Gain Control ◽  
Spatial Location ◽  
Sine Wave ◽  
Harmonic Frequency ◽  
Contrast Gain ◽  
Contrast Response Function ◽  
Contrast Response

In the early visual system, suppression occurs between neurons representing different stimulus properties. This includes features such as orientation (cross-orientation suppression), eye-of-origin (interocular suppression) and spatial location (surround suppression), which are thought to involve distinct anatomical pathways. We asked if these separate routes to suppression can be differentiated by their pattern of gain control on the contrast response function measured in human participants using steady-state electroencephalography. Changes in contrast gain shift the contrast response function laterally, whereas changes in response gain scale the function vertically. We used a Bayesian hierarchical model to summarise the evidence for each type of gain control. A computational meta-analysis of 16 previous studies found the most evidence for contrast gain effects with overlaid masks, but no clear evidence favouring either response gain or contrast gain for other mask types. We then conducted two new experiments, comparing suppression from four mask types (monocular and dichoptic overlay masks, and aligned and orthogonal surround masks) on responses to sine wave grating patches flickering at 5Hz. At the occipital pole, there was strong evidence for contrast gain effects in all four mask types at the first harmonic frequency (5Hz). Suppression generally became stronger at more lateral electrode sites, but there was little evidence of response gain effects. At the second harmonic frequency (10Hz) suppression was stronger overall, and involved both contrast and response gain effects. Although suppression from different mask types involves distinct anatomical pathways, gain control processes appear to serve a common purpose, which we suggest might be to suppress less reliable inputs.

Derivation of the Visual Contrast Response Function by Maximizing Information Rate

2002 ◽  
Vol 14 (3) ◽  
pp. 527-542 ◽  
Author(s):  
Allan Gottschalk
Keyword(s):  
Gain Control ◽  
Information Rate ◽  
Maximal Response ◽  
Early Vision ◽  
Contrast Gain ◽  
Contrast Gain Control ◽  
Ratio Equation ◽  
Visual Contrast ◽  
Contrast Response Function ◽  
Contrast Response

A graph of neural output as a function of the logarithm of stimulus intensity often produces an S-shaped function, which is frequently modeled by the hyperbolic ratio equation. The response of neurons in early vision to stimuli of varying contrast is an important example of this. Here, the hyperbolic ratio equation with a response exponent of two is derived exactly by considering the balance between information rate and the neural costs of making that information available, where neural costs are a function of synaptic strength and spike rate. The maximal response and semisaturation constant of the neuron can be related to the stimulus ensemble and therefore shift accordingly to exhibit contrast gain control and normalization.

Crossmodal attention alters auditory contrast sensitivity

2012 ◽  
Vol 25 (0) ◽  
pp. 177
Author(s):  
Vivian Ciaramitaro ◽  
Dan Jentzen
Keyword(s):  
Visual Attention ◽  
Contrast Sensitivity ◽  
Response Function ◽  
Visual Processing ◽  
Visual Task ◽  
Contrast Gain ◽  
Crossmodal Attention ◽  
Visual Contrast ◽  
Contrast Response Function ◽  
Contrast Response

We examined the influence of covert, endogenous, crossmodal attention on auditory contrast sensitivity in a two-interval forced-choice dual-task paradigm. Attending to a visual stimulus has been found to alter the visual contrast response function via a mechanism of contrast gain for sustained visual attention, or a combination of response gain and contrast gain for transient visual attention (Ling and Carrasco, 2006). We examined if and how auditory contrast sensitivity varied as a function of attentional load, the difficulty of a competing visual task, and how such effects compared to those found for the influences of attention on visual processing. In our paradigm, subjects listened to two sequential white noise stimuli, one of which was amplitude modulated. Subjects reported which interval contained the amplitude modulated auditory stimulus. At the same time a sequence of 5 letters was presented, in an rsvp stream at central fixation, for each interval. Subjects judged which interval contained the visual target. For a given block of trials, subjects judged which interval contained white letters (easy visual task) or, in a separate block of trials, which interval had more target letters ‘A’ (difficult visual task). We found that auditory thresholds were lower for the easy compared to the difficult visual task and that the shift in the auditory contrast response function was reminiscent of a contrast gain mechanism for visual contrast. Importantly, we found that the effects of crossmodal attention on the auditory contrast response function diminished with practice.

scholarly journals Steady-state measures of visual suppression

2021 ◽  
Vol 17 (10) ◽  
pp. e1009507
Author(s):  
Daniel H. Baker ◽  
Greta Vilidaite ◽  
Alex R. Wade
Keyword(s):  
Steady State ◽  
Response Function ◽  
Second Harmonic ◽  
Meta Analysis ◽  
Gain Control ◽  
Sine Wave ◽  
Harmonic Frequency ◽  
Contrast Gain ◽  
Contrast Response Function ◽  
Contrast Response

In the early visual system, suppression occurs between neurons representing different stimulus properties. This includes features such as orientation (cross-orientation suppression), eye-of-origin (interocular suppression) and spatial location (surround suppression), which are thought to involve distinct anatomical pathways. We asked if these separate routes to suppression can be differentiated by their pattern of gain control on the contrast response function measured in human participants using steady-state electroencephalography. Changes in contrast gain shift the contrast response function laterally, whereas changes in response gain scale the function vertically. We used a Bayesian hierarchical model to summarise the evidence for each type of gain control. A computational meta-analysis of 16 previous studies found the most evidence for contrast gain effects with overlaid masks, but no clear evidence favouring either response gain or contrast gain for other mask types. We then conducted two new experiments, comparing suppression from four mask types (monocular and dichoptic overlay masks, and aligned and orthogonal surround masks) on responses to sine wave grating patches flickering at 5Hz. At the occipital pole, there was strong evidence for contrast gain effects in all four mask types at the first harmonic frequency (5Hz). Suppression generally became stronger at more lateral electrode sites, but there was little evidence of response gain effects. At the second harmonic frequency (10Hz) suppression was stronger overall, and involved both contrast and response gain effects. Although suppression from different mask types involves distinct anatomical pathways, gain control processes appear to serve a common purpose, which we suggest might be to suppress less reliable inputs.

scholarly journals Contrast Gain Reduction in Fly Motion Adaptation

Neuron ◽  
2000 ◽  
Vol 28 (2) ◽  
pp. 595-606 ◽  
Author(s):  
Robert A. Harris ◽  
David C. O'Carroll ◽  
Simon B. Laughlin
Keyword(s):  
Motion Adaptation ◽  
Contrast Gain ◽  
Gain Reduction

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.

A Simple Coding Procedure Enhances a Neuron's Information Capacity

1981 ◽  
Vol 36 (9-10) ◽  
pp. 910-912 ◽  
Author(s):  
Simon Laughlin
Keyword(s):  
Information Theory ◽  
Probability Distribution ◽  
Response Function ◽  
Compound Eye ◽  
Information Capacity ◽  
Cumulative Probability ◽  
Natural Scenes ◽  
First Order ◽  
Contrast Response Function ◽  
Contrast Response

Abstract The contrast-response function of a class of first order intemeurons in the fly's compound eye approximates to the cumulative probability distribution of contrast levels in natural scenes. Elementary information theory shows that this matching enables the neurons to encode contrast fluctuations most efficiently.

scholarly journals Porcine global flash multifocal electroretinogram: Possible mechanisms for the glaucomatous changes in contrast response function

2008 ◽  
Vol 48 (16) ◽  
pp. 1726-1734 ◽  
Author(s):  
Patrick H.W. Chu ◽  
Henry H.L. Chan ◽  
Yiu-fai Ng ◽  
Brian Brown ◽  
Andrew W. Siu ◽  
...  
Keyword(s):  
Response Function ◽  
Multifocal Electroretinogram ◽  
Global Flash ◽  
Contrast Response Function ◽  
Contrast Response
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