Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Review Article
  • Published:

Space and time in visual context

An Erratum to this article was published on 01 November 2007

Key Points

  • Visual processing of a feature or object is powerfully affected by its context, that is, its spatial and temporal neighbourhood. It is important to achieve a comprehensive understanding of how and why this is the case, from neural, perceptual and functional perspectives. We focus on tilt as a paradigmatic example, given the large body of historical and recent literature. We also emphasize similarities with other visual attributes and sensory domains.

  • Spatial and temporal context have often been treated separately in the literature. Nevertheless, despite quite different demands on their neural substrate (for example, memory for temporal context, but horizontal intraareal interactions for spatial context), they are closely tied, both functionally and in terms of their impact on vision.

  • Spatial and temporal context exhibit strikingly similar effects in many experimental circumstances. Psychophysical effects include perceptual biases, which are apparent in illusions and after-effects; physiological effects include suppression of the mean firing rate and changes in tuning curves.

  • Mechanistic population models of orientation tuning suggest a link between changes at the neural population level and perceptual changes. In these models, perceptual biases arise due to the 'coding catastrophe' (or decoding ambiguity): downstream mechanisms are unaware of the changes in tuning caused by contextual stimuli, and therefore err when such changes take place.

  • From a functional viewpoint, two main questions exist. First, why are these biases so similar for spatial and temporal contexts; and second, why do contextual stimuli induce perceptual biases at all? In answer to the first question, the obvious source of similarities is the shared statistical regularity in natural visual scenes, with a small patch of image in a scene being typically similar (in properties such as orientation) to patches observed simultaneously in nearby spatial regions and to patches that were recently observed.

  • The reason behind the functional benefit of contextual biases is more contentious: we discuss exciting directions in recent literature, focusing on computational frameworks of efficient coding and Bayesian inference. Natural scene statistics over space and time can inform both of the above frameworks.

  • These directions have the potential to unify our understanding of spatial and temporal contextual processing. Such unified approaches also highlight the many gaps in our current understanding and suggest future perspectives for physiological, psychophysical and computational investigations.

Abstract

No sensory stimulus is an island unto itself; rather, it can only properly be interpreted in light of the stimuli that surround it in space and time. This can result in entertaining illusions and puzzling results in psychological and neurophysiological experiments. We concentrate on perhaps the best studied test case, namely orientation or tilt, which gives rise to the notorious tilt illusion and the adaptation tilt after-effect. We review the empirical literature and discuss the computational and statistical ideas that are battling to explain these conundrums, and thereby gain favour as more general accounts of cortical processing.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Examples of contextual tilt.
Figure 2: Example experimental data for spatial and temporal context effects.
Figure 3: Mechanistic population model for spatial and temporal context.
Figure 4: Statistics of natural movies for time and space.
Figure 5: Correlation within a tuning curve population model.

Similar content being viewed by others

References

  1. Clifford, C. W. & Rhodes, G. (eds) Fitting the Mind to the World Adaptation and After-Effects in High-Level Vision (Oxford University Press, 2005). This book comprehensively covers a wealth of aspects of and perspectives on adaptation, ranging from orientation to high level processing (such as of faces), and from physiology to perception and functional perspectives.

    Google Scholar 

  2. Wohlgemuth, A. On the after-effect of seen movement. Bri. J. Psychol. (Suppl.) 1, 1–117 (1911).

    Google Scholar 

  3. Adelson, E. H. in The New Cognitive Neurosciences (ed. Gazzaniga, M.) 339–351 (MIT Press, Cambridge, Massachusetts, 2000).

    Google Scholar 

  4. Eagleman, D. M., Jacobson, J. E. & Sejnowski, T. J. Perceived luminance depends on temporal context. Nature 428, 854–856 (2004).

    CAS  PubMed  PubMed Central  Google Scholar 

  5. Gibson, J. J. Adaptation, after-effect, and contrast in the perception of tilted lines. J. Exp. Psychol. 20, 553–569 (1937). Pioneering paper that introduced the tilt after-effect, a striking perceptual effect that has been studied intensively over the years.

    Google Scholar 

  6. Webster, M. A., Georgeson, M. A. & Webster, S. M. Neural adjustments to image blur. Nature Neurosci. 5, 839–840 (2002).

    CAS  PubMed  Google Scholar 

  7. Webster, M. A., Kaping, D., Mizokami, Y. & Duhamel, P. Adaptation to natural facial categories. Nature 428, 557–561 (2004).

    CAS  PubMed  Google Scholar 

  8. Leopold, D. A., Rhodes, G., Müller, K. M. & Jeffery, L. The dynamics of visual adaptation to faces. Proc. Biol. Sci. 272, 897–904 (2005).

    PubMed  PubMed Central  Google Scholar 

  9. Oxenham, A. J. Forward masking: adaptation or integration? J. Acoust. Soc. Am. 109, 732–741 (2001).

    CAS  PubMed  Google Scholar 

  10. Wallace, M. T. et al. Unifying multisensory signals across time and space. Exp. Brain Res. 158, 252–258 (2004).

    CAS  PubMed  Google Scholar 

  11. Series, P., Lorenceau, J. & Frégnac, Y. The “silent” surround of V1 receptive fields: theory and experiments. J. Physiol. Paris 97, 453–474 (2003).

    PubMed  Google Scholar 

  12. Albright, T. D. & Stoner, G. R. Contextual influences on visual processing. Annu. Rev. Neurosci. 25, 339–379 (2002).

    CAS  PubMed  Google Scholar 

  13. Dragoi, V. & Sur, M. in The Visual Neuroscience (eds Chalupa, L. M. & Werner, J. S.) 1654–1664 (MIT Press, 2003).

    Google Scholar 

  14. Krekelberg, B., Boynton, G. M. & van Wezel, R. J. Adaptation: from single cells to BOLD signals. Trends Neurosci. 29, 250–256 (2006).

    CAS  PubMed  Google Scholar 

  15. Katz, Y., Heiss, J. E. & Lampl, I. Cross-whisker adaptation of neurons in the rat barrel cortex. J. Neurosci. 26, 13363–13372 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  16. Wachtler, T., Sejnowski, T. J. & Albright, T. D. Representation of color stimuli in awake macaque primary visual cortex. Neuron 37, 681–691 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Li, Z. Border ownership from intracortical interactions in visual area V2. Neuron 47, 143–153 (2005).

    CAS  Google Scholar 

  18. Wenderoth, P. & Johnstone, S. The different mechanisms of the direct and indirect tilt illusions. Vision Res. 28, 301–312 (1988).

    CAS  PubMed  Google Scholar 

  19. Clifford, C. W., Wenderoth, P. & Spehar, B. A functional angle on some after-effects in cortical vision. Proc. R. Soc. Lond. B Biol. Sci. 267, 1705–1710 (2000). Puts forth a functional model based on efficient coding principles for understanding both spatial and temporal perceptual context effects within a common framework.

    CAS  Google Scholar 

  20. Webster, M. A., Malkoc, G., Bilson, A. C. & Webster, S. M. Color contrast and contextual influences on color appearance. J. Vis. 2, 505–519 (2002).

    PubMed  Google Scholar 

  21. Guo, K. et al. Effects on orientation perception of manipulating the spatio-temporal prior probability of stimuli. Vision Res. 44, 2349–2358 (2004).

    PubMed  Google Scholar 

  22. Durant, S. & Clifford, C. W. Dynamics of the influence of segmentation cues on orientation perception. Vision Res. 46, 2934–2940 (2006).

    PubMed  Google Scholar 

  23. Polat, U. & Sagi, D. Temporal asymmetry of collinear lateral interactions. Vision Res. 46, 953–960 (2006).

    PubMed  Google Scholar 

  24. Felsen, G., Touryan, J. & Dan, Y. Contextual modulation of orientation tuning contributes to efficient processing of natural stimuli. Network 16, 139–149 (2005). Emphasizes that similarities in image statistics over space and time can explain experimental similarities in cortical processing (specifically, in terms of repulsive shifts in tuning curves due to spatial and temporal context).

    PubMed  Google Scholar 

  25. Shepherd, A. J. Increased visual after-effects following pattern adaptation in migraine: a lack of intracortical excitation? Brain 124, 2310–2318 (2001).

    CAS  PubMed  Google Scholar 

  26. Hubel, D. & Wiesel, T. Receptive fields, binocular interaction, and functional architecture in the cat's visual cortex. J. Physiol. (Lond.) 160, 106–154 (1962).

    CAS  Google Scholar 

  27. Seung, H. S. & Sompolinsky, H. Simple models for reading neuronal population codes. Proc. Natl Acad. Sci. USA 90, 10749–10753 (1993).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Snippe, H. P. Parameter extraction from population codes: a critical assessment. Neural Comput. 8, 511–529 (1996).

    CAS  PubMed  Google Scholar 

  29. Pouget, A., Dayan, P. & Zemel, R. Information processing with population codes. Nature Rev. Neurosci. 1, 125–132 (2000).

    CAS  Google Scholar 

  30. Coppola, D. M., Purves, H. R., McCoy, A. N. & Purves, D. The distribution of oriented contours in the real world. Proc. Natl Acad. Sci. USA 95, 4002–4006 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  31. Cavanaugh, J. R., Bair, W. & Movshon, J. A. Selectivity and spatial distribution of signals from the receptive field surround in macaque V1 neurons. J. Neurophysiol. 88, 2547–2556 (2002).

    PubMed  Google Scholar 

  32. Müller, J. R., Metha, A. B., Krauskopf, J. & Lennie, P. Local signals from beyond the receptive fields of striate cortical neurons. J. Neurophysiol. 90, 822–831 (2003).

    PubMed  Google Scholar 

  33. van der Smagt, M. J., Wehrhahn, C. & Albright, T. D. Contextual masking of oriented lines: interactions between surface segmentation cues. J. Neurophysiol. 94, 576–589 (2005).

    PubMed  Google Scholar 

  34. Knierim, J. J. & van Essen, D. C. Neuronal responses to static texture patterns in area V1 of the alert macaque monkey. J. Neurophysiol. 67, 961–980 (1992).

    CAS  PubMed  Google Scholar 

  35. Nothdurft, H. C., Gallant, J. L. & Essen, D. C. V. Response modulation by texture surround in primate area V1: correlates of “popout” under anesthesia. Vis. Neurosci. 16, 15–34 (1999).

    CAS  PubMed  Google Scholar 

  36. Li, W., Thier, P. & Wehrhahn, C. Contextual influence on orientation discrimination of humans and responses of neurons in V1 of alert monkeys. J. Neurophysiol. 83, 941–954 (2000).

    CAS  PubMed  Google Scholar 

  37. Sengpiel, F., Sen, A. & Blakemore, C. Characteristics of surround inhibition in cat area 17. Exp. Brain Res. 116, 216–228 (1997).

    CAS  PubMed  Google Scholar 

  38. Müller, J. R., Metha, A. B., Krauskopf, J. & Lennie, P. Rapid adaptation in visual cortex to the structure of images. Science 285, 1405–1408 (1999).

    PubMed  Google Scholar 

  39. Dragoi, V., Sharma, J. & Sur, M. Adaptation-induced plasticity of orientation tuning in adult visual cortex. Neuron 28, 287–298 (2000).

    CAS  PubMed  Google Scholar 

  40. Crowder, N. A. et al. Relationship between contrast adaptation and orientation tuning in V1 and V2 of cat visual cortex. J. Neurophysiol. 95, 271–283 (2006).

    CAS  PubMed  Google Scholar 

  41. Levitt, J. B. & Lund, J. S. Contrast dependence of contextual effects in primate visual cortex. Nature 387, 73–76 (1997).

    CAS  PubMed  Google Scholar 

  42. Kohn, A. & Movshon, J. A. Adaptation changes the direction tuning of macaque MT neurons. Nature Neurosci. 7, 764–772 (2004). Demonstrates the importance of studying systems hierarchically, reporting that population tuning changes at one level (in the primary visual cortex) can differ markedly from tuning changes at the next level (in the motion processing middle temporal area).

    CAS  PubMed  Google Scholar 

  43. Gilbert, C. D. & Wiesel, T. N. The influence of contextual stimuli on the orientation selectivity of cells in primary visual cortex of the cat. Vision Res. 30, 1689–1701 (1990).

    CAS  PubMed  Google Scholar 

  44. Li, C. Y., Lei, J. J. & Yao, H. S. Shift in speed selectivity of visual cortical neurons: a neural basis of perceived motion contrast. Proc. Natl Acad. Sci. USA 96, 4052–4056 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  45. Greenlee, M. W. & Magnussen, S. Saturation of the tilt aftereffect. Vision Res. 27, 1041–1043 (1987).

    CAS  PubMed  Google Scholar 

  46. Wenderoth, R. & van der Zwan, R. The effects of exposure duration and surrounding frames on direct and indirect tilt aftereffects and illusions. Percept. Psychophys. 46, 338–344 (1989).

    CAS  PubMed  Google Scholar 

  47. Schrater, P. R. & Simoncelli, E. P. Local velocity representation: evidence from motion adaptation. Vision Res. 38, 3899–3912 (1998).

    CAS  PubMed  Google Scholar 

  48. Mather, G., Verstraten, F. & Anstis, S. (eds) The Motion Aftereffect (MIT press, Massachusetts, USA, 1998).

    Google Scholar 

  49. Morgan, M., Chubb, C. & Solomon, J. A. Predicting the motion after-effect from sensitivity loss. Vision Res. 46, 2412–2420 (2006).

    CAS  PubMed  Google Scholar 

  50. Solomon, J. A. & Morgan, M. J. Stochastic re-calibration: contextual effects on perceived tilt. Proc. Biol. Sci. 273, 2681–2686 (2006).

    PubMed  PubMed Central  Google Scholar 

  51. Mareschal, I., Sceniak, M. P. & Shapley, R. M. Contextual influences on orientation discrimination: binding local and global cues. Vision Res. 41, 1915–1930 (2001).

    CAS  PubMed  Google Scholar 

  52. Dragoi, V., Sharma, J., Miller, E. K. & Sur, M. Dynamics of neuronal sensitivity in primate V1 underlying local feature discrimination. Nature Neurosci. 883–891 (2002).

  53. Westheimer, G. & Gee, A. Opposing views on orthogonal adaptation: a response to Clifford, Arnold, Smith, and Pianta (2003). Vision Res. 43, 721–722 (2003).

    PubMed  Google Scholar 

  54. Regan, D. & Beverley, K. I. Postadaptation orientation discrimination. J. Opt. Soc. Am. A 2, 147–155 (1985).

    CAS  PubMed  Google Scholar 

  55. Clifford, C. W., Arnold, D. H., Smith, S. T. & Pianta, M. Opposing views on orthogonal adaptation: a reply to Westheimer and Gee (2002). Vision Res. 43, 717–719 (2003).

    PubMed  Google Scholar 

  56. Clifford, C. W., Wyatt, A. M., Arnold, D. H., Smith, S. T. & Wenderoth, P. Orthogonal adaptation improves orientation discrimination. Vision Res. 41, 151–159 (2001).

    CAS  PubMed  Google Scholar 

  57. Barlow, H. B., Macleod, D. I. A. & van Meeteren, A. Adaptation to gratings: no compensatory advantages found. Vision Res. 16, 1043–1045 (1976).

    CAS  PubMed  Google Scholar 

  58. Jin, D. Z., Dragoi, V., Sur, M. & Seung, H. S. Tilt aftereffect and adaptation-induced changes in orientation tuning in visual cortex. J. Neurophysiol. 94, 4038–4050 (2005). Demonstrates how changes in tuning curves observed in cortical adaptation data can give rise to perceptual repulsion and attraction within a population decoding model.

    PubMed  Google Scholar 

  59. Averbeck, B. B., Latham, P. E. & Pouget, A. Neural correlations, population coding and computation. Nature Rev. Neurosci. 7, 358–366 (2006).

    CAS  Google Scholar 

  60. Fairhall, A. L., Lewen, G. D., Bialek, W. & de Ruyter Van Steveninck, R. R. Efficiency and ambiguity in an adaptive neural code. Nature 412, 787–792 (2001). Studies adaptation to variance statistics in a velocity-sensing neuron in the fly, and suggests that it might evade the coding catastrophe by reporting aspects of its state of adaptation through its long-run average firing rate.

    CAS  PubMed  Google Scholar 

  61. Teich, A. F. & Qian, N. Learning and adaptation in a recurrent model of V1 orientation selectivity. J. Neurophysiol. 89, 2086–2100 (2003). Proposes a mechanistic population decoding model and draws out the perceptual implications for two different timescales of temporal context, namely adaptation and learning.

    PubMed  Google Scholar 

  62. Li, Z. A saliency map in primary visual cortex. Trends Cogn. Sci. 6, 9–16 (2002).

    PubMed  Google Scholar 

  63. Barlow, H. B. in Vision: Coding and Efficiency (ed. Blakemore, C.) 363–375 (Cambridge University Press, New York, USA,1990). Barlow is a pioneer in the application of computational principles to explaining neural and psychophysical phenomena; here he discusses his original notion that efficient coding ideas can explain adaptation at the synaptic and perceptual levels.

    Google Scholar 

  64. Webster, M. A., Werner, J. S. & Field, D. J. in Fitting the Mind to the World: Adaptation and Aftereffects in High-Level Vision, Advances in Visual Cognition Series (eds Clifford, C. W. & Rhodes, G. L.) 241–277 (Oxford University Press, USA, 2005). Points out that the effects of adaptation on perceptual discriminability are quite modest compared with the more striking perceptual repulsion, and suggests alternative functional frameworks with a focus on societal norms.

    Google Scholar 

  65. Field, D. J. What is the goal of sensory coding? Neural Comput. 6, 559–601 (1994).

    Google Scholar 

  66. Simoncelli, E. P. & Olshausen, B. A. Natural image statistics and neural representation. Annu. Rev. Neurosci. 24, 1193–1216 (2001).

    CAS  PubMed  Google Scholar 

  67. Li, Z. & Atick, J. J. Towards a theory of the striate cortex. Neural Comput. 6, 127–146 (1994).

    Google Scholar 

  68. Olshausen, B. A. & Field, D. J. Emergence of simple-cell receptive field properties by learning a sparse factorial code. Nature 381, 607–609 (1996).

    CAS  PubMed  Google Scholar 

  69. Bell, A. J. & Sejnowski, T. J. The 'independent components' of natural scenes are edge filters. Vision Res. 37, 3327–3338 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  70. Li, Z. Theoretical understanding of the early visual processes by data compression and data selection. Network 17, 301–334 (2006). A review of theoretical frameworks for understanding early visual processing, including the notion that intracortical connections in the primary visual cortex are responsible for computing a map of the salience of regions of visual space, and that this can explain properties that are opaque to efficient coding principles.

    CAS  Google Scholar 

  71. Field, D. J., Hayes, A. & Hess, R. F. Contour integration by the human visual system: evidence for a local “association field”. Vision Res. 33, 173–193 (1993).

    CAS  PubMed  Google Scholar 

  72. Elder, J. H. & Goldberg, R. M. Ecological statistics of Gestalt laws for the perceptual organization of contours. J. Vis. 2, 324–353 (2002).

    PubMed  Google Scholar 

  73. Olshausen, B. A. & Field, D. J. Vision and the coding of natural images. Am. Sci. 88, 238–244 (2000).

    Google Scholar 

  74. Baddeley, R. The correlational structure of natural images and the calibration of spatial representations. Cogn. Sci. 21, 351–372 (1997).

    Google Scholar 

  75. Dong, D. W. & Atick, J. J. Statistics of natural time-varying images. Network 6 345–358 (1995).

    Google Scholar 

  76. Grzywacz, N. M. & de Juan, J. Sensory adaptation as Kalman filtering: theory and illustration with contrast adaptation. Network 14, 465–482 (2003).

    PubMed  Google Scholar 

  77. Geman, S. & Geman, D. Stochastic relaxation, Gibbs distributions, and the Bayesian restoration of images. IEEE. Trans. Pat. Anal. Mach. Intell. 6, 721–741 (1984).

    CAS  Google Scholar 

  78. Kersten, D. Predictability and redundancy of natural images. J. Opt. Soc. Am. A 4, 2395–2400 (1987).

    CAS  PubMed  Google Scholar 

  79. Schwartz, O. & Simoncelli, E. P. Natural signal statistics and sensory gain control. Nature Neurosci. 4, 819–825 (2001).

    CAS  PubMed  Google Scholar 

  80. Hoyer, P. & Hyvärinen, A. A multi-layer sparse coding network learns contour coding from natural images. Vision Res. 42, 1593–1605 (2002).

    PubMed  Google Scholar 

  81. Karklin, Y. & Lewicki, M. S. A hierarchical Bayesian model for learning nonlinear statistical regularities in nonstationary natural signals. Neural Comput. 17, 397–423 (2005).

    PubMed  Google Scholar 

  82. Zetzsche, C. & Nuding, U. Nonlinear and higher-order approaches to the encoding of natural scenes. Network 16, 191–221 (2005).

    PubMed  Google Scholar 

  83. Schwartz, O., Sejnowski, T. J. & Dayan, P. Soft mixer assignment in a hierarchical generative model of natural scene statistics. Neural Comput. 18, 2680–2718 (2006).

    PubMed  PubMed Central  Google Scholar 

  84. Hyvärinen, A., Hurri, J. & Väyrynen, J. Bubbles: a unifying framework for low-level statistical properties of natural image sequences. J. Opt. Soc. Am. A Opt. Image Sci. Vis. 20, 1237–1252 (2003).

    PubMed  Google Scholar 

  85. Sigman, M., Cecchi, G. A., Gilbert, C. D. & Magnasco, M. O. On a common circle: natural scenes and Gestalt rules. Proc. Natl Acad. Sci. USA 98, 1935–1940 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  86. Geisler, W. S., Perry, J. S., Super, B. J. & Gallogly, D. P. Edge co-occurrence in natural images predicts contour grouping performance. Vision Res. 41, 711–724 (2001). Examines both absolute and Bayesian orientation spatial context statistics in natural images, and derives a model of contour grouping that is compared to perception.

    CAS  PubMed  Google Scholar 

  87. Howe, C. Q. & Purves, D. Natural-scene geometry predicts the perception of angles and line orientation. Proc. Natl Acad. Sci. USA 102, 1228–1233 (2005). Measures image statistics of overlapping orientations in space, and suggests how these can give rise to perceptual tilt illusions.

    CAS  PubMed  PubMed Central  Google Scholar 

  88. Dragoi, V. & Sur, M. Image structure at the center of gaze during free viewing. J. Cogn. Neurosci. 18, 737–748 (2006).

    PubMed  Google Scholar 

  89. Melcher, D. Spatiotopic transfer of visual-form adaptation across saccadic eye movements. Curr. Biol. 15, 1745–1748 (2005).

    CAS  PubMed  Google Scholar 

  90. Burr, D. & Morrone, M. C. Eye movements: building a stable world from glance to glance. Curr. Biol. 15, R839–R840 (2005).

    CAS  PubMed  Google Scholar 

  91. Barlow, H. B. in Sensory Communication (ed. Rosenblith, W. A.) 217–234 (MIT press, Massachusetts, 1961).

    Google Scholar 

  92. Attneave, F. Some informational aspects of visual perception. Psychol. Rev. 61, 183–193 (1954).

    CAS  PubMed  Google Scholar 

  93. Shannon, C. A mathematical theory of communication. Bell Sys. Tech. J. 27, 379–423 (1948).

    Google Scholar 

  94. Barlow, H. B. Redundancy reduction revisited. Network 12, 241–253 (2001).

    CAS  PubMed  Google Scholar 

  95. Simoncelli, E. P. Vision and the statistics of the visual environment. Curr. Opin. Neurobiol. 13, 144–149 (2003). Reviews the efficient coding hypothesis in recent literature, covering aspects of experimental testing of these principles and computational models based on efficient coding of natural images.

    CAS  PubMed  Google Scholar 

  96. Barlow, H. B. & Foldiak, P. in The Computing Neuron (eds Miall, C., Durbin, R. M. & Mitchison, G. J.) 54–72 (Addison-Wesley, England, 1989).

    Google Scholar 

  97. Atick, J. J. & Redlich, A. N. Towards a theory of early visual processing. Neural Comput. 2, 308–320 (1990).

    Google Scholar 

  98. Atick, J. J., Li, Z. & Redlich, A. N. What does post-adaptation color appearance reveal about cortical color representation? Vision Res. 33, 123–129 (1993).

    CAS  PubMed  Google Scholar 

  99. Dan, Y., Atick, J. J. & Reid, R. C. Efficient coding of natural scenes in the lateral geniculate nucleus: experimental test of a computational theory. J. Neurosci. 16, 3351–3362 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

  100. Smith, E. & Lewicki, M. Efficient auditory coding. Nature 439, 978–982 (2006).

    CAS  PubMed  Google Scholar 

  101. Wainwright, M. J., Schwartz, O. & Simoncelli, E. P. in Probabilistic Models of the Brain: Perception and Neural Function (eds Rao, R., Olshausen, B. A. & Lewicki, M.) 203–222 (MIT Press, Massachusetts, USA, 2002).

    Google Scholar 

  102. Geisler, W. S. & Albrecht, D. G. Cortical neurons: isolation of contrast gain control. Vision Res. 8, 1409–1410 (1992).

    Google Scholar 

  103. Heeger, D. J. Normalization of cell responses in cat striate cortex. Vis. Neurosci. 9, 181–198 (1992).

    CAS  PubMed  Google Scholar 

  104. Vinje, W. E. & Gallant, J. L. Sparse coding and decorrelation in primary visual cortex during natural vision. Science 287, 1273–1276 (2000). Suggests that spatial context increases the efficiency of cortical neural processing.

    CAS  PubMed  Google Scholar 

  105. Movellan, J. R., Wachtler, T., Albright, T. D. & Sejnowski, T. J. in Neural Information Processing Systems (eds Becker, S., Thrun, S. & Obermayer, K.) 205–212 (MIT Press, Massachusetts, USA, 2002).

    Google Scholar 

  106. Schwartz, O., Movellan, J. R., Wachtler, T., Albright, T. D. & Sejnowski, T. J. Spike count distributions, factonizability, and contextual effects in area V1. Neurocomputing 58–60 (2004).

  107. Wainwright, M. J. Visual adaptation as optimal information transmission. Vision Res. 39, 3960–3974 (1999). Proposes that adaptation serves to optimize information transmission in an efficient coding context, using the tilt after-effect as a key example.

    CAS  PubMed  Google Scholar 

  108. Foldiak, P. Forming sparse representations by local anti-Hebbian learning. Biol. Cybern. 64, 165–170 (1990).

    CAS  PubMed  Google Scholar 

  109. Bednar, J. A. & Miikkulainen, R. Tilt aftereffects in a self-organizing model of the primary visual cortex. Neural Comput. 12, 1721–1740 (2000).

    CAS  PubMed  Google Scholar 

  110. Sirosh, J. & Miikkulainen, R. Topographic receptive fields and patterned lateral interaction in a self-organizing model of the primary visual cortex. Neural Comput. 9, 577–594 (1997).

    CAS  PubMed  Google Scholar 

  111. Doya, K., Ishii, S., Pouget, A. & Rao, R. P. N. (eds) Bayesian Brain: Probabilistic Approaches to Neural Coding (MIT Press, Massachusetts, USA, 2007).

    Google Scholar 

  112. Yuille, A. & Bulthoff, H. H. in Bayesian Decision Theory and Psychophysics (eds Knill, D. and Richards, W.) 123–161 (Cambridge University Press, New York, USA, 1996).

    Google Scholar 

  113. Yuille, A. & Kersten, D. Vision as Bayesian inference: analysis by synthesis? Trends Cogn. Sci. 10, 301–308 (2006).

    PubMed  Google Scholar 

  114. Balboa, R. M. & Grzywacz, N. M. The minimal local-asperity hypothesis of early retinal lateral inhibition. Neural Comput. 12, 1485–1517 (2000).

    CAS  PubMed  Google Scholar 

  115. Grzywacz, N. M. & Balboa, R. M. A Bayesian framework for sensory adaptation. Neural Comput. 14, 543–559 (2002).

    PubMed  Google Scholar 

  116. Weiss, Y., Simoncelli, E. P. & Adelson, E. H. Motion illusions as optimal percepts. Nature Neurosci. 5, 598–604 (2002).

    CAS  PubMed  Google Scholar 

  117. Stocker, A. A. & Simoncelli, E. P. Noise characteristics and prior expectations in human visual speed perception. Nature Neurosci. 9, 578–585 (2006).

    CAS  PubMed  Google Scholar 

  118. Kersten, D., Mamassian, P. & Yuille, A. Object perception as Bayesian inference. Annu. Rev. Psychol. 55, 271–304 (2004).

    PubMed  Google Scholar 

  119. Stocker, A. A. & Simoncelli, E. P. in NIPS Advances in Neural Information Processing Systems (eds Weiss, Y., Schölkopf, B. & Platt, J.) 1291–1298 (MIT Press, Massachusetts, USA, 2006). Proposes a Bayesian model of visual adaption in terms of adjustments to the likelyhood, on the important basis that changes to the prior are likely to lead to perceptual attraction rather than repulsion.

    Google Scholar 

  120. Schwartz, O., Sejnowski, T. J. & Dayan, P. in Advances in Neural Information Processing Systems 18 (eds Weiss, Y., Schölkopf, B. & Platt, J.) 1201–1208 (MIT Press, Massachusetts, USA, 2006).

    Google Scholar 

  121. Körding, K. & Tenenbaum, J. B. in Advances in Neural Information Processing Systems (eds Schölkopf, B., Platt, J. & Hoffman, T.) 737–744 (The MIT Press, Massachussets, USA, 2006).

    Google Scholar 

  122. Over, R. Comparison of normalization theory and neural enhancement explanation of negative aftereffects. Psychol. Bull. 75, 225–243 (1971).

    CAS  PubMed  Google Scholar 

  123. Andrews, D. P. Error-correcting perceptual mechanisms. Q. J. Exp. Psychol. 16, 104–115 (1964).

    Google Scholar 

  124. Mitchell, D. E. & Muir, D. W. Does the tilt after-effect occur in the oblique meridian? Vision Res. 16, 609–613 (1976).

    CAS  PubMed  Google Scholar 

  125. Leopold, D. A., Bondar, I. V. & Giese, M. A. Norm-based face encoding by single neurons in the monkey inferotemporal cortex. Nature 442, 572–575 (2006).

    CAS  PubMed  Google Scholar 

  126. Neisser, U. Cognitive Psychology (Prentice-Hall, New Jersey, USA, 1967).

    Google Scholar 

  127. Hinton, G. E. & Ghahramani, Z. Generative models for discovering sparse distributed representations. Philos. Trans. R. Soc. Lond. B Biol. Sci. 352, 1177–1190 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  128. Grenander, U. & Srivastava, A. Probabibility models for clutter in natural images. IEEE. Trans. Patt. Anal. Mach. Intell. 23, 423–429 (2002).

    Google Scholar 

  129. Zhu, S. & Mumford, D. Prior learning and gibbs reaction-diffusion. IEEE. Trans. Patt. Anal. Mach. Intell. 19, 1236–1250 (1997).

    Google Scholar 

  130. Nundy, S. & Purves, D. A probabilistic explanation of brightness scaling. Proc. Natl Acad. Sci. USA 99, 14482–14487 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  131. Gilchrist, A. L. et al. An anchoring theory of lightness perception. Psychol. Rev. 4, 795–834 (1999).

    Google Scholar 

  132. Andrews, D. P. & Mallows, C. Scale mixtures of normal distributions. J. R. Stat. Soc. 36, 99–102 (1974).

    Google Scholar 

  133. Wainwright, M. J. & Simoncelli, E. P. in Advances in Neural Information Processing Systems (eds Solla, S. A., Leen, T. K. & Müller, K. R.) 855–861 (MIT Press, Massachusetts, USA, 2000).

    Google Scholar 

  134. Portilla, J., Strela, V., Wainwright, M. & Simoncelli, E. P. Image denoising using a scale mixture of Gaussians in the wavelet domain. IEEE. Trans. Image Process. 12, 1338–1351 (2003).

    PubMed  Google Scholar 

  135. Schwartz, O., Sejnowski, T. J. & Dayan, P. The tilt illusion, population decoding, and natural scene statistics. Computational and Systems Neuroscience (COSYNE) Abstract 280 (2007).

  136. Rao, R. P. & Ballard, D. H. Predictive coding in the visual cortex: a functional interpretation of some extra-classical receptive-field effects. Nature Neurosci. 2, 79–87 (1999).

    CAS  PubMed  Google Scholar 

  137. Srinivasan, M. V., Laughlin, S. B. & Dubs, A. Predictive coding: a fresh view of inhibition in the retina. Proc. R. Soc. Lond. B Biol. Sci. 216, 427–459 (1982).

    CAS  PubMed  Google Scholar 

  138. Hosoya, T., Baccus, S. A. & Meister, M. Dynamic predictive coding by the retina. Nature 436, 71–77 (2005).

    CAS  PubMed  Google Scholar 

  139. Mackay, D. M. in Automata Studies (eds Shannon, C. E. & McCarthy, J.) 235–251 (Princeton University Press, New Jersey, USA, 1956).

    Google Scholar 

  140. Kapadia, M. K., Ito, M., Gilbert, C. D. & Westheimer, G. Improvement in visual sensitivity by changes in local context: parallel studies in human observers and in V1 of alert monkeys. Neuron 15, 843–856 (1995).

    CAS  PubMed  Google Scholar 

  141. Polat, U. & Sagi, D. Lateral interactions between spatial channels: suppression and facilitation revealed by lateral masking experiments. Vision Res. 33, 993–999 (1993).

    CAS  PubMed  Google Scholar 

  142. Magnussen, S. & Johnsen, T. Temporal aspects of spatial adaptation. A study of the tilt aftereffect. Vision Res. 26, 661–672 (1986).

    CAS  PubMed  Google Scholar 

  143. Rose, D. A square root law for adaptation to contrast? Vision Res. 32, 1781–1788 (1992).

    CAS  PubMed  Google Scholar 

  144. Kanai, R. & Verstraten, F. A. Perceptual manifestations of fast neural plasticity: motion priming, rapid motion aftereffect and perceptual sensitization. Vision Res. 45, 3109–3116 (2005).

    PubMed  Google Scholar 

  145. Muir, D. & Over, R. Tilt aftereffects in central and peripheral vision. J. Exp. Psychol. 85, 165–170 (1970).

    CAS  PubMed  Google Scholar 

  146. Solomon, J. A., Felisberti, F. M. & Morgan, M. J. Crowding and the tilt illusion: toward a unified account. J. Vis. 4, 500–508 (2004).

    PubMed  Google Scholar 

  147. Roberts, M. J. & Thielle, A. Attention and contrast modulate the influence of spatio-temporal context in orientation discrimination of human subjects. FENS abstract 3, A053.15 (2006).

  148. Kapadia, M. K., Westheimer, G. & Gilbert, C. D. Spatial distribution of contextual interactions in primary visual cortex and in visual perception. J. Neurophysiol. 84, 2048–2062 (2000).

    CAS  PubMed  Google Scholar 

  149. Li, Z. Computational design and nonlinear dynamics of a recurrent network model of the primary visual cortex. Neural Comput. 13, 1749–1780 (2001).

    CAS  PubMed  Google Scholar 

  150. Pelli, D. G. & Farell, B. Why use noise? J. Opt. Soc. Am. A 16, 647–653 (1999).

    CAS  Google Scholar 

  151. Meese, T. S. & Georgeson, M. A. The tilt aftereffect in plaids and gratings: channel codes, local signs and “patchwise” transforms. Vision Res. 36, 1421–1437 (1996).

    CAS  PubMed  Google Scholar 

  152. Georgeson, M. A. Human vision combines oriented filters to compute edges. Proc. Biol. Sci. 249, 235–245 (1992).

    CAS  PubMed  Google Scholar 

  153. Smith, S., Wenderoth, P. & van der Zwan, R. Orientation processing mechanisms revealed by the plaid tilt illusion. Vision Res. 41, 483–494 (2001).

    CAS  PubMed  Google Scholar 

  154. Foley, J. M. & Boynton, G. M. Forward pattern masking and adaptation: effects of duration, interstimulus interval, contrast, and spatial and temporal frequency. Vision Res. 33, 959–980 (1993).

    CAS  PubMed  Google Scholar 

  155. Foley, J. M. & Yang, Y. D. Forward pattern masking: effects of spatial frequency and contrast. J. Opt. Soc. Am. A 8, 2026–2037 (1991).

    CAS  PubMed  Google Scholar 

  156. Wehrhahn, C. & Dresp, B. Detection facilitation by collinear stimuli in humans: dependence on strength and sign of contrast. Vision Res. 38, 423–428 (1998).

    CAS  PubMed  Google Scholar 

  157. Tanaka, Y. & Sagi, D. Long-lasting, long-range detection facilitation. Vision Res. 38, 2591–2599 (1998).

    CAS  PubMed  Google Scholar 

  158. Zenger-Landolt, B. & Koch, C. Flanker effects in peripheral contrast discrimination–psychophysics and modeling. Vision Res. 41, 3663–3675 (2001).

    CAS  PubMed  Google Scholar 

  159. Chen, C. C. & Tyler, C. W. Lateral modulation of contrast discrimination: flanker orientation effects. J. Vis. 2, 520–530 (2002).

    PubMed  Google Scholar 

  160. Greenlee, M. W. & Heitger, F. The functional role of contrast adaptation. Vision Res. 28, 791–797 (1988).

    CAS  PubMed  Google Scholar 

  161. Maattanen, L. M. & Koenderink, J. J. Contrast adaptation and contrast gain control. Exp. Brain Res. 87, 205–212 (1991).

    CAS  PubMed  Google Scholar 

  162. Clifford, C. W. Perceptual adaptation: motion parallels orientation. Trends Cogn. Sci. 6, 136–143 (2002). Demonstrates perceptual analogies in the adaptation to orientation and motion, suggesting that common computational principles may underly contextual processing in both domains.

    PubMed  Google Scholar 

  163. Cavanaugh, J. R., Bair, W. & Movshon, J. A. Nature and interaction of signals from the receptive field center and surround in macaque V1 neurons. J. Neurophysiol. 88, 2530–2546 (2002).

    PubMed  Google Scholar 

  164. Albrecht, D. G., Farrar, S. B. & Hamilton, D. B. Spatial contrast adaptation characteristics of neurones recorded in the cat's visual cortex. J. Physiol. (Lond.) 347, 713–739 (1984).

    CAS  Google Scholar 

  165. Ohzawa, I., Sclar, G. & Freeman, R. D. Contrast gain control in the cat's visual system. J. Neurophysiol. 54, 651–667 (1985).

    CAS  PubMed  Google Scholar 

  166. Kapadia, M. K., Westheimer, G. & Gilbert, C. D. Dynamics of spatial summation in primary visual cortex of alert monkeys. Proc. Natl Acad. Sci. USA 21, 12073–12078 (1999).

    Google Scholar 

  167. Sceniak, M. P., Ringach, D. L., Hawken, M. J. & Shapley, R. Contrast's effect on spatial summation by macaque V1 neurons. Nature Neurosci. 2, 733–739 (1999).

    CAS  PubMed  Google Scholar 

  168. Webb, B. S., Dhruv, N. T., Solomon, S. G., Tailby, C. & Lennie, P. Early and late mechanisms of surround suppression in striate cortex of macaque. J. Neurosci. 25, 11666–11675 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  169. Walker, G. A., Ohzawa, I. & Freeman, R. D. Disinhibition outside receptive fields in the visual cortex. J. Neurosci. 22, 5659–5668 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  170. Carandini, M., Movshon, J. A. & Ferster, D. Pattern adaptation and cross-orientation interactions in the primary visual cortex. Neuropharmacology 37, 501–511 (1998).

    CAS  PubMed  Google Scholar 

  171. Sharpee, T. O. et al. Adaptive filtering enhances information transmission in visual cortex. Nature 439, 936–942 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  172. Fuster, J. M. Memory in the Cerebral Cortex: An Empirical Approach to Neural Networks in the Human and Nonhuman Primate (MIT Press, Massachusetts, USA, 1995).

    Google Scholar 

  173. Goldman-Rakic, P. S. Regional and cellular fractionation of working memory. Proc. Natl Acad. Sci. USA 93, 13473–13480 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

  174. Miller, E. K. & Cohen, J. D. An integrative theory of prefrontal cortex function. Annu. Rev. Neurosci. 24, 167–202 (2001).

    CAS  PubMed  Google Scholar 

  175. Renart, A., Song, O. & Wang, X. J. Robust spatial working memory through homeostatic synaptic scaling in heterogeneous cortical networks. Neuron 38, 473–485 (2003).

    CAS  PubMed  Google Scholar 

  176. Abbott, L. F., Varela, J. A., Sen, K. & Nelson, S. B. Synaptic depression and cortical gain control. Science 275, 220–224 (1997).

    CAS  PubMed  Google Scholar 

  177. Markram, H. & Tsodyks, M. V. Redistribution of synaptic efficacy between neocortical pyramidal neurones. Nature 382, 807–809 (1996).

    CAS  PubMed  Google Scholar 

  178. Chance, F. S., Nelson, S. B. & Abbott, L. F. Synaptic depression and the temporal response characteristics of V1 cells. J. Neurosci. 18, 4785–4799 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  179. Fusi, S., Drew, P. J. & Abbott, L. F. Cascade models of synaptically stored memories. Neuron 45, 599–611 (2005).

    CAS  PubMed  Google Scholar 

  180. Drew, P. J. & Abbott, L. F. Models and properties of power-law adaptation in neural systems. J. Neurophysiol. 96, 826–833 (2006).

    PubMed  Google Scholar 

  181. Wang, X. J., Liu, Y., Sanchez-Vives, M. V. & McCormick, D. A. Adaptation and temporal decorrelation by single neurons in the primary visual cortex. J. Neurophysiol. 89, 3279–3293 (2003).

    PubMed  Google Scholar 

  182. Carandini, M. Visual cortex: fatigue and adaptation. Curr. Biol. 10, R605–R607 (2000).

    CAS  PubMed  Google Scholar 

  183. Sanchez-Vives, M. V., Nowak, L. G. & McCormick, D. A. Cellular mechanisms of long-lasting adaptation in visual cortical neurons. J. Neurosci. 20, 4286–4299 (2000).

    CAS  PubMed  PubMed Central  Google Scholar 

  184. Nowak, L. G., Sanchez-Vives, M. V. & McCormick, D. A. Role of synaptic and intrinsic membrane properties in short-term receptive field dynamics in cat area 17. J. Neurosci. 25, 1866–1880 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  185. Fitzpatrick, D. The functional organization of local circuits in visual cortex: insights from the study of tree shrew striate cortex. Cereb. Cortex 6, 329–341 (1996).

    CAS  PubMed  Google Scholar 

  186. Angelucci, A. & Bullier, J. Reaching beyond the classical receptive field of V1 neurons: horizontal or feedback axons? J. Physiol. Paris 97, 141–154 (2003).

    PubMed  Google Scholar 

  187. Levitt, J. B. & Lund, J. S. The spatial extent over which neurons in macaque striate cortex pool visual signals. Vis. Neurosci. 19, 439–452 (2002).

    PubMed  Google Scholar 

  188. Bair, W., Cavanaugh, J. R. & Movshon, J. A. Time course and time-distance relationships for surround suppression in macaque V1 neurons. J. Neurosci. 23, 7690–7601 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  189. Stetter, M., Bartsch, H. & Obermayer, K. A mean-field model for orientation tuning, contrast saturation, and contextual effects in the primary visual cortex. Biol. Cybern. 82, 291–304 (2000).

    CAS  PubMed  Google Scholar 

  190. Bressloff, P. C. & Cowan, J. D. An amplitude equation approach to contextual effects in visual cortex. Neural Comput. 14, 493–525 (2002).

    PubMed  Google Scholar 

  191. Sullivan, T. J. & de Sa, V. R. A model of surround suppression through cortical feedback. Neural Netw. 19, 564–572 (2006).

    PubMed  Google Scholar 

  192. Schwabe, L., Obermayer, K., Angelucci, A. & Bressloff, P. C. The role of feedback in shaping the extra-classical receptive field of cortical neurons: a recurrent network model. J. Neurosci. 26, 9117–9129 (2006).

    CAS  PubMed  PubMed Central  Google Scholar 

  193. Das, A. & Gilbert, C. D. Topography of contextual modulations mediated by short-range interactions in primary visual cortex. Nature 399, 655–661 (1999).

    CAS  PubMed  Google Scholar 

  194. Okamoto, T., Watanabe, M., Aihara, K. & Kondo, S. An explanation of contextual modulation by short-range isotropic connections and orientation map geometry in the primary visual cortex. Biol. Cybern. 91, 396–407 (2004).

    PubMed  Google Scholar 

  195. Wielaard, J. & Sajda, P. Extraclassical receptive field phenomena and short-range connectivity in V1. Cereb. Cortex 16, 1531–1545 (2006).

    PubMed  Google Scholar 

  196. Dragoi, V., Rivadulla, C. & Sur, M. Foci of orientation plasticity in visual cortex. Nature 411, 80–86 (2001).

    CAS  PubMed  Google Scholar 

  197. Gelbtuch, M. H., Calvert, J. E., Harris, J. P. & Phillipson, O. T. Modification of visual orientation illusions by drugs which influence dopamine and GABA neurones: differential effects on simultaneous and successive illusions. Psychopharmacology (Berl.) 90, 379–383 (1986).

    CAS  Google Scholar 

  198. Borst, A., Flanagin, V. L. & Sompolinsky, H. Adaptation without parameter change: dynamic gain control in motion detection. Proc. Natl Acad. Sci. USA 102, 6172–6176 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  199. Boynton, G. M. & Finney, E. M. Orientation-specific adaptation in human visual cortex. J. Neurosci. 23, 8781–8787 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  200. Fraser, J. A new visual illusion of direction. Brit. J. Psych. 2, 307–320 (1908).

    Google Scholar 

  201. Kayser, W., Einhauser, C. & Konig, P. Temporal correlations of orientations in natural scenes. Neurocomputing 52–54, 117–123 (2003).

    Google Scholar 

  202. Simoncelli, E. P., Freeman, W. T., Adelson, E. H. & Heeger, D. J. Shiftable multi-scale transforms. IEEE. Trans. Inform. Theory 38, 587–607 (1992).

    Google Scholar 

  203. Simoncelli, E. P. in Proc. 31st Asilomar conf. on Signals, Systems and Computers 673–678 (Pacific Grove, California, USA, 1997).

    Google Scholar 

Download references

Acknowledgements

This work was funded by the Howard Hughes Medical Institute (O.S.), the Gatsby Charitable Foundation (A.H., P.D.), the Biotechnology and Biological Sciences Research Council, the Engineering and Physical Sciences Research Council and the Wellcome Trust (P.D). We are very grateful to C. Clifford, A. Kohn, A. Stocker and J. Solomon for comments on the manuscript and discussion, and to T. Sejnowski and E. Simoncelli for discussion.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Odelia Schwartz.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Related links

Related links

FURTHER INFORMATION

Odelia Schwarts's homepage

Pater Dayan's homepage

Glossary

Saccade

A rapid eye movement (with speeds of up to 800° per second) that brings the point of maximal visual acuity — the fovea — to the image of interest.

Orientation tuning

The property of visual neurons to only respond to stimuli (images) with a certain orientation or tilt (for example, vertically orientated bars).

Tuning curve

A tuning curve to a feature (such as orientation) is the curve describing the average response of a neuron as a function of the feature values.

Rotation invariance

When each input angle is treated in the same way; that is, when the input rotates, the output rotates.

Discrimination threshold

The smallest difference between two visual stimuli (for example, vertical versus tilted bars) that can reliably (that is, with a given probability of error) be reported by an observer.

Population code

Sensory events that are encoded by neuronal populations rather than by individual neurons.

Poisson spiking neuron

A simple model neuron for which the number of spikes emitted in a given time is Poisson distributed about a mean firing rate. Spikes are assumed to be independent both in time and across neurons.

Fisher information

Measures how quickly the likelihood of the population responses changes with stimulus parameters, and thereby provides a decoder-independent quantification of the potential accuracy of decoding (the Cramér-Rao lower bound).

Mean square estimation error

Estimation error can be quantified by the squared difference between the (population-based) estimate and its true value. The mean of this over trials is one measure of the accuracy of an estimate.

Efficient coding

When information is coded in an efficient and non-redundant manner, for instance, when the outputs of neurons in the population are statistically independent.

Bayes (Bayesian approach)

A statistical method that allows the use of prior information to evaluate the posterior probabilities of different hypotheses.

Kalman filter

A recursive formulation that estimates the present outcome dynamically in time, based on prior information and noisy measurements.

Markov random field

An undirected graphical model that represents statistical dependencies between a set of variables. The Markov property is that a variable associated with one location in the image is only directly influenced by variables associated with neighbouring locations.

Linear (or second order) de-correlation

Random variables are de-correlated if the off-diagonal elements of their covariance matrix (representing the second order statistics) are equal to zero. De-correlation is in general a weaker requirement than independence, because higher order statistics may still exhibit dependencies.

Divisive normalization

Strictly speaking, when (for example) sum output across a population is kept constant by dividing each response by a (trial-dependent) quantity. Looser versions model gain control mechanisms in V1 and elsewhere.

Gain control

When the (for example) sum output across a population is used to adjust the gain to an appropriate level for a range of input signal levels, with higher signal levels resulting in higher gain and reduced response. Stricter versions are denoted divisive normalization.

anti-Hebbian learning

A learning rule whereby whenever two units or neurons are active simultaneously, the effective connection between them becomes less excitatory or more inhibitory.

Bayesian inference

Inference according to the standard laws of probability, notably including Bayes theorem. Conclusions are based on posterior distributions arising from combining observations (as probabilistic likelihoods) with prior information.

Prior

A probability distribution that captures the belief or expectation about a variable, in the absence of observations or evidence. Here, priors are specified through personal or evolutionary experience of environmental statistics.

Decision-theoretic loss function

The loss (or cost) associated with a particular decision about a quantity as a function of its true values. Bayesian decision theory suggests that choices should be made by minimizing expected losses under posterior distributions.

Gibson's normalization

The hypothesis that replusive biases arise in the orientation domain due to a long-run prior favouring absolute cardinal axes.

Power law synapses

A synaptic adaptation that is (time) scale invariant; for example, having the same response shape at multiple timescales. This is in contrast to an exponential adaptation process with a single time constant.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Schwartz, O., Hsu, A. & Dayan, P. Space and time in visual context. Nat Rev Neurosci 8, 522–535 (2007). https://doi.org/10.1038/nrn2155

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1038/nrn2155

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing