Color Vision: Decoding Color Space

A new study has used magnetoencephalography to track cortical responses color as they emerge in time. Similarities and differences within these neural parallel characteristics of the perceptual experience color. It is still common describe vision terms two stages. In first, light spectrum sampled by three classes retinal cone receptors with different spectral sensitivities. second, signals are compared post-receptoral channels that encode attributes like hue saturation light. But dividing machinery this way — between initial rest brain a bit saying main parts dissertation signature page thesis. may feel students during their defense, but dichotomy hides an intricate story many chapters, most which unread. reported issue Current Biology Rosenthal et al.1Rosenthal I.A. Singh S.R. Hermann K.L. Pantazis D. Conway B.R. Color space geometry uncovered magnetoencephalography.Curr. Biol. 2021; 31: 515-526Abstract Full Text PDF Scopus (2) Google Scholar sheds further on probing over One nervous systems represent information through populations neurons tuned properties stimulus. These tuning preferences typically arranged systematically brain. For example, areas visual system retinotopically, so nearby cells respond locations (and thus image falling mosaic retina)2Wandell B.A. Winawer J. Imaging retinotopic maps human brain.Vis. Res. 2011; 51: 718-737Crossref PubMed (206) Scholar. ‘maps’ can provide representation space, linking processing However, highly distorted more devoted sampling our central foveal than periphery, receptive field size or spatial area captured individual also increases eccentricity. This why we see clearly at center gaze: discriminations better fovea because same stimulus difference produces larger response when shown versus peripheral vision. some judgments falloff sensitivity eccentricity corresponds reasonably changes sampling, performance be equated scaling stimulate constant number magnification factor3Rovamo Virsu V. Nasanen R. Cortical factor predicts photopic contrast vision.Nature. 1978; 271: 54-56Crossref (308) Thus, distortions impact perception, raise exciting possibility could reverse engineer aspects percepts from code. Within beyond maps, there arrangements neuronal for inputs, such eye dominance subpathway, features edge orientation, size, color4Livingstone M. Hubel Segregation form, color, movement, depth: anatomy, physiology, perception.Science. 1988; 240: 740-749Crossref (2207) combinations carried distinct cell types retina, course layers lateral geniculate nucleus5Lee B.B. coding primate pathway: historical view.J. Opt. Soc. Am. A. 2014; A103-A112Crossref (10) Many studies have explored how inputs transformed areas, V1–V4 VO, form representations revealed important point variety stages along stream6Xiao Y. Wang Felleman D.J. spatially organized colour macaque V2.Nature. 2003; 421: 535-539Crossref (187) Scholar,7Lafer-Sousa Parallel, multi-stage colors, faces shapes inferior temporal cortex.Nat. Neurosci. 2013; 16: 1870-1878Crossref (126) The serve ends. Could higher ventral stream predict biases color8Brouwer G.J. Heeger Decoding reconstructing cortex.J. 2009; 29: 13992-14003Crossref (282) (Figure 1)? study, examined four hues luminance levels, uniformly retinogeniculate representation, then analysed similar were samples. work follows long tradition exploring mechanisms using techniques: recording activity population measured noninvasively monitoring electrical (EEG/ERG) related hemodynamic (fMRI, example) color-specific throughout pathway, although differing areas8Brouwer Scholar,9Gegenfurtner K.R. vision.Nat. Rev. 4: 563-572Crossref (259) dynamics interplay remain poorly understood. work, (MEG), measures activity-dependent magnetic fields high resolution, providing powerful window into change time10Sandhaeger F. von Nicolai C. Miller E.K. Siegel Monkey EEG links motion across species scales.eLife. 2019; 8e45645Crossref include faster chromatic stimuli, dimensions time; authors explore interaction separate paper11Hermann K. I. S. Temporal encoding magnetoencephalography.bioRxiv. 2020; https://doi.org/10.1101/2020.06.17.155713Crossref Analyses prominent perception. identifying substrates appearance proven difficult. interesting lightness: while often treated independent appear largely separable markedly depending whether brighter darker surround. particular, yellow exists only increment, becomes brown decrement12Buck S.L. Brown. Curr. 2015; 25: R536-R537Abstract (11) 1B). was dissimilar dark versions orange/yellow hue, other (particularly blue) remained level. While it striking reflected patterns activity, do not know structure brain, environment, causes us way. addition analogs percepts, notable intriguing findings. pattern participants appeared reverberate time after 275 milliseconds, potentially reflecting late role recurrent networks representation. Another stimuli words, very delays (?900 ms), words did responses, failing support close association conceptual relationship perception cognition actively debated13Lupyan G. Abdel Rahman Boroditsky L. Clark Effects language perception.Trends Cogn. Sci. 24: 930-944Abstract (15) Scholar,14Firestone Scholl B.J. "Top-down" effects where none should found: El Greco fallacy research.Psychol. 38-46Crossref (124) Scholar, would might differ languages that, unlike English, treat blues categories15Martinovic Paramei G.V. MacInnes W.J. Russian reveal limits influencing discrimination.Cognition. 201: 104281Crossref (4) back build metric color? attempts been made create uniform equal distances correspond perception16Smet Whitehead Webster M.A. simple principled approach understanding metrics.J. 2016; 33: A319-A331Crossref (12) What depends percept, however, scalings required judgments, just noticeable salience large differences. involved tasks, segmenting scene judging surface materials even expression face. processes underlying analyses involve pathways contributes vary widely. Moreover, reports pure red one person next17Emery K.J. Individual implications perception.Curr. Opin. Behav. 30: 28-33Crossref given measure reveals challenging. Consider again maps: equate varies task18Westheimer grain perifoveal field.Vis. 1982; 22: 157-162Crossref (238) despite distortion world compressed periphery. map(s) therefore single space. question what extent ‘space’. cones constrains three-dimensional trichromatic, encourages idea colors coordinates, however framework considerable explanatory power. We coordinates similar, order continuously similarities19Shepard R.N. Cooper L.A. Representation blind, color-blind, normally sighted.Psychol. 1992; 3: 97-104Crossref (119) Yet untrained observers, intuitive opposite is, let alone orthogonal20Webster Verriest Lecture: Adventures blue yellow.J. 37: V1-V14Crossref (8) relationships readily compute need to. utility experiencing uncertain, objects categories computable vectors. sense, purples oranges apples oranges. Space Geometry Uncovered MagnetoencephalographyRosenthal al.Current BiologyNovember 16, 2020In BriefRosenthal, Singh, Hermann, al. use decode By analyzing similarity among varying luminance, discover dynamic universal color-naming makes predictions Full-Text