Suprathreshold contrast response in normal and anomalous trichromats

Knoblauch, Kenneth; Marsh-Armstrong, Brennan; Werner, John S.

doi:10.1101/788331

Cited by 3 publications

(4 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results point to strong compensation for color losses in anomalous trichromacy through amplification of cortical responses to chromatic contrast. This in turn suggests that the greater than expected responses to colors observed behaviorally [17-19] may reflect actual gain changes in early cortical processing. Both the neural and behavioral evidence are not inconsistent with the profound sensitivity losses in color-anomalous observers in threshold discrimination for color, since these thresholds are limited by noise, which may also be amplified by the gain change [14, 15, 47].…”

Section: Discussionmentioning

confidence: 95%

“…Yet despite this theoretical importance, whether and how color compensation occurs in anomalous trichromacy remains poorly understood (for review see [13] and [16]. The tasks indicating compensation tend to involve judging the similarity or size or salience of color differences [17-19], and thus could potentially reflect conceptual rather than perceptual adaptations. There have been few direct tests of compensation by measuring neural activity [20], and to our knowledge none using functional MRI to assess color processing in anomalous trichromats, a technique that has been shown to be an effective measure of color and contrast coding throughout cortex [21-26] [27-30].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Color compensation in anomalous trichromats assessed with fMRI

Tregillus

Isherwood

Vanston

et al. 2020

Preprint

View full text Add to dashboard Cite

Anomalous trichromacy is a common form of congenital color-deficiency resulting from a genetic alteration in the photopigments of the eye's light receptors. The changes reduce sensitivity to reddish-greenish hues, yet previous work suggests that these observers may experience the world to be more colorful than their altered receptor sensitivities would predict, potentially indicating an amplification of post-receptoral signals. However, past evidence suggesting such a gain adjustment rests on subjective measures of color appearance or salience. We directly tested for neural amplification by using fMRI to measure cortical responses in color-anomalous and normal control observers. Color contrast response functions were measured in two experiments with different tasks to control for attentional factors. Both experiments showed a predictable reduction in chromatic responses for anomalous trichromats in primary visual cortex. However, in later areas V2v and V3v, chromatic responses in the two groups were indistinguishable. Our results provide direct evidence for neural plasticity that compensates for the deficiency in the initial receptor color signals and suggest that the site of this compensation is in early visual cortex.

show abstract

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Color compensation in anomalous trichromats assessed with fMRI

Tregillus

Isherwood

Vanston

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…For example, anomalous trichromacy (the most common inherited color deficiency) results in a shift in the L or M peak sensitivity so that they are much closer together. This reduces the strength of the difference signals produced by the L ‐ M channel, yet measurements of these observers' suprathreshold color percepts differ less than expected from those of standard trichromats 73,74 …”

Section: Effects Of Individual Cone Fundamentals Differences On Color Appearancementioning

confidence: 92%

Color appearance model incorporating contrast adaptation—Implications for individual differences in color vision

Smet¹,

Webster

Whitehead

2021

Color Research & Application

View full text Add to dashboard Cite

Color appearance models are usually based on equations with fixed numerical coefficients that were predetermined to yield optimal agreement for a selected standard observer. Here we address the well‐known fact that, among color‐normal observers, there are significant differences of cone fundamentals, which often cause observer metamerism. This is not fully addressed by many appearance models. It might seem that observer metamerism could be accurately predicted by substituting an individual's color matching functions into an otherwise‐unchanged color appearance model, but this is not assured because the model's coefficients were not designed for the new observer. Here we explore a solution related to how the visual system tends to compensate for changes in color information arising from variations cone fundamentals. For this purpose, we developed a simple color appearance model that uses only a few numerical coefficients, yet accurately predicts the perceptual attributes of Munsell samples under a selected standard lighting condition. We then added a feedback loop to adjust the model coefficients automatically, in response to switching between the cone fundamentals for different observers. This feature is intended to model long term contrast adaptation in the vision system by maintaining the average long‐term levels of color contrast. Incorporating this adaptation principle into color appearance models could allow better assessments of displays and illumination systems, to help improve color appearances for most observers.

show abstract

“…Additionally, the response range along the d scale of the visual component in the face task is only about one-third smaller than that for the auditory component in the voice task. These observations suggest that integration mechanisms are capable of adjusting modality specific weights to compensate for differences in the range of input signals as has been demonstrated in anomalous color vision (MacLeod, 2003;Knoblauch et al, 2020;Tregillus et al, 2020).…”

Section: Discussionmentioning

confidence: 60%

The Role of Unimodal Feedback Pathways in Gender Perception During Activation of Voice and Face Areas

Abbatecola

Gerardin

Beneyton

et al. 2021

Front. Syst. Neurosci.

Self Cite

View full text Add to dashboard Cite

Cross-modal effects provide a model framework for investigating hierarchical inter-areal processing, particularly, under conditions where unimodal cortical areas receive contextual feedback from other modalities. Here, using complementary behavioral and brain imaging techniques, we investigated the functional networks participating in face and voice processing during gender perception, a high-level feature of voice and face perception. Within the framework of a signal detection decision model, Maximum likelihood conjoint measurement (MLCM) was used to estimate the contributions of the face and voice to gender comparisons between pairs of audio-visual stimuli in which the face and voice were independently modulated. Top–down contributions were varied by instructing participants to make judgments based on the gender of either the face, the voice or both modalities (N = 12 for each task). Estimated face and voice contributions to the judgments of the stimulus pairs were not independent; both contributed to all tasks, but their respective weights varied over a 40-fold range due to top–down influences. Models that best described the modal contributions required the inclusion of two different top–down interactions: (i) an interaction that depended on gender congruence across modalities (i.e., difference between face and voice modalities for each stimulus); (ii) an interaction that depended on the within modalities’ gender magnitude. The significance of these interactions was task dependent. Specifically, gender congruence interaction was significant for the face and voice tasks while the gender magnitude interaction was significant for the face and stimulus tasks. Subsequently, we used the same stimuli and related tasks in a functional magnetic resonance imaging (fMRI) paradigm (N = 12) to explore the neural correlates of these perceptual processes, analyzed with Dynamic Causal Modeling (DCM) and Bayesian Model Selection. Results revealed changes in effective connectivity between the unimodal Fusiform Face Area (FFA) and Temporal Voice Area (TVA) in a fashion that paralleled the face and voice behavioral interactions observed in the psychophysical data. These findings explore the role in perception of multiple unimodal parallel feedback pathways.

show abstract

Suprathreshold contrast response in normal and anomalous trichromats

Cited by 3 publications

References 56 publications

Color compensation in anomalous trichromats assessed with fMRI

Color compensation in anomalous trichromats assessed with fMRI

Color appearance model incorporating contrast adaptation—Implications for individual differences in color vision

The Role of Unimodal Feedback Pathways in Gender Perception During Activation of Voice and Face Areas

Contact Info

Product

Resources

About