Colour tuning in human visual cortex measured with functional magnetic resonance imaging

Engel, Stephen A.; Zhang, Xuemei; Wandell, Brian A.

doi:10.1038/40398

Cited by 319 publications

(236 citation statements)

References 30 publications

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“…The three panels show measurements using (L ϩ M)-cone, (L Ϫ M)-cone, or S-cone stimuli. Previous reports found that V1 is most responsive to (L Ϫ M)-cone, less responsive to (L ϩ M)-cone, and least responsive to S-cone stimuli per unit cone contrast (Kleinschmidt et al, 1996;Engel et al, 1997a). We confirm these responsivity differences.…”

Section: Psychophysicssupporting

confidence: 80%

Specializations for Chromatic and Temporal Signals in Human Visual Cortex

Liu¹,

Wandell²

2005

J. Neurosci.

109

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Neurological case studies and qualitative measurements suggest that regions within human extrastriate cortex are specialized for different perceptual functions, including color. However, there are few quantitative measurements of human extrastriate color specializations. We studied the chromatic and temporal responses in several different clusters of human visual field maps using functional magnetic resonance imaging. Contrast response functions were measured for luminance [(L ϩ M)-cone], red-green [(L Ϫ M)-cone] and blueyellow (S-cone) modulations at various temporal frequencies. In primary visual cortex (V1), temporal responsivities to luminance and red-green modulations are approximately constant up to 10 Hz, but responsivities to blue-yellow modulations decrease significantly. In ventral occipital cortex (VO), all colors elicit strong responses, and, for each color, low temporal frequency modulations are more effective than high temporal frequency modulations. Hence, VO represents the full range of color information but does not respond well to rapid modulations. Conversely, in human motion-selective cortex (MTϩ) and V3A, blue-yellow modulations elicit very weak responses, whereas luminance and red-green high temporal frequency modulations are equally or more effective than low temporal frequency modulations. Hence, these dorsal occipital regions respond well to rapid modulations, but not all color information is represented. Similar to human motion perception, MTϩ and V3A respond powerfully to all temporal frequencies but only to some colors. Similar to human color perception, VO responds powerfully to all colors but only to relatively low temporal frequencies.

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Section: Psychophysicssupporting

confidence: 80%

Specializations for Chromatic and Temporal Signals in Human Visual Cortex

Liu¹,

Wandell²

2005

J. Neurosci.

109

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“…Area V4 was de¢ned in one of the authors (E.M.H.) using standard functional magnetic resonance imaging methods for de¢ning retinotopic visual areas (Engel et al 1994(Engel et al , 1997; the location of the number area was estimated from the results of Rickard et al (2000) (average coordinates for left hemisphere, À29.5, À54.8 and À12.0).…”

Section: Methods and Resultsmentioning

confidence: 99%

Psychophysical investigations into the neural basis of synaesthesia

Ramachandran

Hubbard

2001

Proc. R. Soc. Lond. B

339

309

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We studied two otherwise normal, synaesthetic subjects who`saw' a speci¢c colour every time they saw a speci¢c number or letter. We conducted four experiments in order to show that this was a genuine perceptual experience rather than merely a memory association. (i) The synaesthetically induced colours could lead to perceptual grouping, even though the inducing numerals or letters did not.(ii) Synaesthetically induced colours were not experienced if the graphemes were presented peripherally. (iii) Roman numerals were ine¡ective: the actual number grapheme was required. (iv) If two graphemes were alternated the induced colours were also seen in alternation. However, colours were no longer experienced if the graphemes were alternated at more than 4 Hz. We propose that grapheme colour synaesthesia arises from`cross-wiring' between the`colour centre' (area V4 or V8) and the`number area', both of which lie in the fusiform gyrus. We also suggest a similar explanation for the representation of metaphors in the brain: hence, the higher incidence of synaesthesia among artists and poets.

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“…Furthermore, colour channels are included to capture complementary chromatic information. Interestingly, evidence from biological systems suggests that they exploit similar complementary feature combination in their visual processing [10,13,15,26,34].…”

Section: Technical Approach 21 Complementary Spacetime Orientation Dmentioning

confidence: 99%

Spacetime Forests with Complementary Features for Dynamic Scene Recognition

Feichtenhofer¹,

Pinz²,

Wildes³

2013

Procedings of the British Machine Vision Conference 2013

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This paper presents spacetime forests defined over complementary spatial and temporal features for recognition of naturally occurring dynamic scenes. The approach improves on the previous state-of-the-art in both classification and execution rates. A particular improvement is with increased robustness to camera motion, where previous approaches have experienced difficulty. There are three key novelties in the approach. First, a novel spacetime descriptor is employed that exploits the complementary nature of spatial and temporal information, as inspired by previous research on the role of orientation features in scene classification. Second, a forest-based classifier is used to learn a multi-class representation of the feature distributions. Third, the video is processed in temporal slices with scale matched preferentially to scene dynamics over camera motion. Slicing allows for temporal alignment to be handled as latent information in the classifier and for efficient, incremental processing. The integrated approach is evaluated empirically on two publically available datasets to document its outstanding performance.

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Colour tuning in human visual cortex measured with functional magnetic resonance imaging

Cited by 319 publications

References 30 publications

Specializations for Chromatic and Temporal Signals in Human Visual Cortex

Specializations for Chromatic and Temporal Signals in Human Visual Cortex

Psychophysical investigations into the neural basis of synaesthesia

Spacetime Forests with Complementary Features for Dynamic Scene Recognition

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