Long-wavelength adaptation reveals slow, spectrally opponent inputs to the human luminance pathway

Stockman, Andrew; Plummer, Daniel J.

doi:10.1167/5.9.5

Cited by 14 publications

(20 citation statements)

References 63 publications

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“…Consistent with this view, three recent, meticulous psychophysical studies revealed strong, non-linear interactions between the human luminance channel and chromatic opponent channels [44]–[46], thus providing the necessary pre-cortical substrate for the correspondence between colour brightness and V1 activity reported here. While arguing for a potential retinal locus for these interactions, these authors also highlighted previous studies showing colour-luminance interactions at the level of single V1 cells [47]–[49].…”

Section: Discussionsupporting

confidence: 84%

The Brightness of Colour

Corney¹,

Haynes

Rees

et al. 2009

PLoS ONE

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BackgroundThe perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour) appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK) effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this ‘illusion’ to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies.ResultsRather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1), if not earlier in the visual system, since the brightness of colours (as opposed to their luminance) accords with activity in V1 as measured with fMRI.ConclusionsThe data suggest that perceptions of brightness represent a robust visual response to the likely sources of stimuli, as determined, in this instance, by the known statistical relationship between scenes and their retinal responses. While the responses of the early visual system (receptors in this case) may represent specifically the statistics of images, post receptor responses are more likely represent the statistical relationship between images and scenes. A corollary of this suggestion is that the visual cortex is adapted to relate the retinal image to behaviour given the statistics of its past interactions with the sources of retinal images: the visual cortex is adapted to the signals it receives from the eyes, and not directly to the world beyond.

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Section: Discussionsupporting

confidence: 84%

The Brightness of Colour

Corney¹,

Haynes

Rees

et al. 2009

PLoS ONE

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“…The inverted and delayed phase delays shown here are not confined to S-cone signals. M-cone phase delays with similar phase characteristics have been reported before under comparable conditions (Stockman & Plummer, 2005a, 2005b. Figure 7 shows such M-cone phase delays measured on the 610-nm background fields decreasing in steps from 10.41 log 10 quanta s j1 deg j2 for KR and from 9.39 log 10 quanta s j1 deg j2 for WL.…”

Section: Sluggish Inverted M-cone Signalssupporting

confidence: 79%

The S-cone contribution to luminance depends on the M- and L-cone adaptation levels: Silent surrounds?

et al. 2009

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Under dim background conditions, the S-cones make little or no contribution to luminance (A. Eisner & D. I. MacLeod, 1980; W. Verdon & A. J. Adams, 1987), yet under conditions of intense long-wavelength adaptation, a small but robust contribution to luminance--as defined by heterochromatic flicker photometry (A. Stockman, D. I. MacLeod, & D. D. DePriest, 1987, 1991) or motion (J. Lee & C. F. Stromeyer, 1989)--can be found. Here, by using selective adaptation and/or tritanopic metamers to isolate the S-cone response, we investigate the dependence of the S-cone luminance input on changes in background wavelength and radiance. Interestingly, the S-cone luminance input disappears completely when no adapting background is present, even though the same S-cone stimulus makes a clear contribution to luminance when a background is present. The dependence of the S-cone luminance input on the wavelength and radiance of the adapting background is surprising. We find that the S-cone signal can be measured on fields of 491 nm and longer wavelengths that exceed a criterion background radiance. These criterion radiances roughly follow an L + M spectral sensitivity, which suggests that the S-cone luminance input is silent unless the L- and M-cones are excited above a certain level. We hypothesize that the L + M cone signals produced by the steady adapting backgrounds somehow "gate" the S-cone luminance signals, perhaps by being modulated by them.

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“…Indeed, similarly large delays are found in many other experiments using L-, M-, and Scone flicker using similarly sized fields (Stockman, Montag, & Plummer, 2006;Stockman & Plummer, 2005a, 2005bStockman, Plummer, & Montag, 2005;Stockman, Sharpe, Zrenner, & Nordby, 1991;Stromeyer et al, 2000). This is a topic we will return to in future papers.…”

Section: Determination Of the Late Filter Shapessupporting

confidence: 64%

Color and brightness encoded in a common L- and M-cone pathway with expansive and compressive nonlinearities

Stockman¹,

Petrova²,

Henning³

2014

Journal of Vision

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Lights near 560 nm appear brighter when flickered, whereas lights near 520 or 650 nm appear yellower. Both effects are consistent with signal distortion within the visual pathway-brightness changes at an expansive nonlinearity, and hue shifts at a compressive one. We previously manipulated the distortion products generated by each nonlinearity to extract the temporal properties of stages of the L-and M-cone pathways that signal brightness and color before (early stages) and after (late stages) each nonlinearity. We find that the attenuation characteristics of the early and late stages are virtually identical in both pathways: The early temporal stage acts like a band-pass filter peaking at 10-15 Hz, while the late stage acts like low-pass filter with a cut-off frequency near 3 Hz. We propose a physiologically relevant model that accounts for the filter shapes and incorporates both nonlinearities within a common parvocellular pathway. The shape of the early band-pass filter is consistent with antagonism between center signals and more sluggish and delayed surround signals, while the late filter is consistent with a simple two-stage low-pass filter. Modeling suggests that the brightness change and hue shift are both initially caused by the half-wave rectification and partition of signals into ON and OFF components. However, the hue shift is probably caused by the additional effects of a later nonlinearity that compresses chromatic red and green signals. Plausible sites for the expansive half-wave rectifying nonlinearity are after surround antagonism, possibly from horizontal cells, but the compressive nonlinearity is likely to be after the late filter.

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Long-wavelength adaptation reveals slow, spectrally opponent inputs to the human luminance pathway

Cited by 14 publications

References 63 publications

The Brightness of Colour

The Brightness of Colour

The S-cone contribution to luminance depends on the M- and L-cone adaptation levels: Silent surrounds?

Color and brightness encoded in a common L- and M-cone pathway with expansive and compressive nonlinearities

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