The primary visual cortex (V1) is probably the best characterized area of primate cortex, but whether this region contributes directly to conscious visual experience is controversial. Early neurophysiological and neuroimaging studies found that visual awareness was best correlated with neural activity in extrastriate visual areas, but recent studies have found similarly powerful effects in V1. Lesion and inactivation studies have provided further evidence that V1 might be necessary for conscious perception. Whereas hierarchical models propose that damage to V1 simply disrupts the flow of information to extrastriate areas that are crucial for awareness, interactive models propose that recurrent connections between V1 and higher areas form functional circuits that support awareness. Further investigation into V1 and its interactions with higher areas might uncover fundamental aspects of the neural basis of visual awareness.
There are two main theories that pertain to the role of the primary visual cortex (V1) in visual awareness. Hierarchical models propose that although V1 provides necessary input, only high-level extrastriate areas that project to frontal-parietal attentional areas are directly involved in awareness. Interactive models propose that dynamic recurrent circuits between V1 and higher areas are necessary to maintain a visual representation in awareness. These models yield different predictions about whether awareness will be impaired by V1 disruption if extrastriate activity remains intact.
V1 damage severely impairs visual awareness, indicating that this region is necessary for normal conscious vision. Lesions to extrastriate areas lead to more specific visual deficits, whereas damage to parietal and/or superior-temporal areas can lead to gross visual neglect of contralateral space. Therefore, no single brain area is sufficient for visual awareness. Nonetheless, V1 seems to be the only single cortical area that is crucial for visual awareness.
Some subjects with V1 lesions can make accurate forced-choice visual discriminations in the absence of reported awareness. These implicit residual abilities (blindsight) presumably reflect the sustained activity that is found in many extrastriate areas, including motion-sensitive areas MT and V3A, and object-sensitive areas V4/V8 and the lateral occipital area. Similarly, motion phosphenes elicited by transcranial magnetic stimulation of area MT can be disrupted by subsequent stimulation to V1, indicating that extrastriate activity alone might be insufficient for awareness and that feedback projections from MT to V1 may be important for awareness of motion.
V1 activity is strongly associated with awareness under certain ambiguous perceptual conditions. During binocular rivalry, awareness spontaneously alternates between two competing monocular images. Human neuroimaging studies have revealed strong awareness-related modulations in V1 during rivalry. Likewise, neurophysiological and functional magnetic resonance imaging studies of visual detection tasks have found that V1 activity is greater for perceived than unperceived targets, and that the degree of response enhancement can predict detection performance.
However, not all studies have found a consistent relationship between V1 activity and awareness, including those of internally generated visual experiences (such as hallucinations, dreaming or imagery). In some studies, changes in perception are associated with increased extrastriate activity and concomitant decreases in V1 activity, indicating a more complex relationship.
Current evidence indicates that V1 activity is necessary for normal conscious perception and is closely associated with some forms of visual awareness. Further investigation of V1 and its interactions with higher areas might provide important insights into the neural basis of visual awareness.
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Felleman, D. J. & Van Essen, D. C. Distributed hierarchical processing in the primate cerebral cortex. Cereb. Cortex 1, 1–47 (1991).
Cowey, A. & Stoerig, P. The neurobiology of blindsight. Trends Neurosci. 14, 140–145 (1991).
Salin, P. A. & Bullier, J. Corticocortical connections in the visual system: structure and function. Physiol. Rev. 75, 107–154 (1995).
Falchier, A., Clavagnier, S., Barone, P. & Kennedy, H. Anatomical evidence of multimodal integration in primate striate cortex. J. Neurosci. 22, 5749–5759 (2002).
Barone, P., Batardiere, A., Knoblauch, K. & Kennedy, H. Laminar distribution of neurons in extrastriate areas projecting to visual areas V1 and V4 correlates with the hierarchical rank and indicates the operation of a distance rule. J. Neurosci. 20, 3263–3281 (2000).
Barlow, H. B., Blakemore, C. & Pettigrew, J. D. The neural mechanism of binocular depth discrimination. J. Physiol. (Lond.) 193, 327–342 (1967).
Cumming, B. G. An unexpected specialization for horizontal disparity in primate primary visual cortex. Nature 418, 633–636 (2002).
Hubel, D. H. & Wiesel, T. N. Receptive fields, binocular interaction, and functional architecture in the cat's visual cortex. J. Physiol. (Lond.) 160, 106–154 (1962).
Hubel, D. H. & Wiesel, T. N. Receptive fields and functional architecture of monkey striate cortex. J. Physiol. (Lond.) 195, 215–243 (1968).
De Valois, K. K., De Valois, R. L. & Yund, E. W. Responses of striate cortex cells to grating and checkerboard patterns. J. Physiol. (Lond.) 291, 483–505 (1979).
Ungerleider, L. G. & Mishkin, M. in Analysis of Visual Behavior (eds Ingle, D. J., Goodale, M. A. & Mansfield, R. J. W.) 549–586 (MIT Press, Cambridge, Massachusetts, 1982).
Inouye, T. Visual Disturbances following Gunshot Wounds of the Cortical Visual Area (translated by M. Glickestein & M. Fahle) (Oxford Univ. Press, Oxford, 2000; Brain 123, Suppl. 1–101).
Holmes, G. Disturbances of vision by cerebral lesions. Brit. J. Ophthalmol. 2, 353–384 (1918).
Rees, G., Kreiman, G. & Koch, C. Neural correlates of consciousness in humans. Nature Rev. Neurosci. 3, 261–270 (2002).
Crick, F. & Koch, C. Are we aware of neural activity in primary visual cortex? Nature 375, 121–123 (1995).
Zeki, S. Localization and globalization in conscious vision. Annu. Rev. Neurosci. 24, 57–86 (2001).
Zeki, S. M. Functional organization of a visual area in the posterior bank of the superior temporal sulcus of the rhesus monkey. J. Physiol. (Lond.) 236, 549–573 (1974).
Zeki, S. M. Colour coding in the superior temporal sulcus of rhesus monkey visual cortex. Proc. R. Soc. Lond. B 197, 195–223 (1977).
Gross, C. G., Bender, D. B. & Rocha-Miranda, C. E. Visual receptive fields of neurons in inferotemporal cortex of the monkey. Science 166, 1303–1306 (1969).
Leopold, D. A. & Logothetis, N. K. Multistable phenomena: changing views in perception. Trends Cogn. Sci. 3, 254–264 (1999).
Pollen, D. A. On the neural correlates of visual perception. Cereb. Cortex 9, 4–19 (1999).
Lamme, V. A. & Roelfsema, P. R. The distinct modes of vision offered by feedforward and recurrent processing. Trends Neurosci. 23, 571–579 (2000).
Bullier, J. Integrated model of visual processing. Brain Res. Brain Res. Rev. 36, 96–107 (2001).
Treisman, A. M. & Gelade, G. A feature-integration theory of attention. Cogn. Psychol. 12, 97–136 (1980).
Baars, B. J. In the Theater of Consciousness: the Workspace of the Mind (Oxford Univ. Press, New York, 1996).
Engel, A. K. & Singer, W. Temporal binding and the neural correlates of sensory awareness. Trends Cogn. Sci. 5, 16–25 (2001).
Tononi, G. & Edelman, G. M. Consciousness and complexity. Science 282, 1846–1851 (1998).
Weiskrantz, L. Blindsight: a Case Study in its Implications (Oxford Univ. Press, Oxford, 1986). A widely cited book that details the discovery and first investigations of blindsight or vision without awareness.
Stoerig, P. & Cowey, A. Wavelength discrimination in blindsight. Brain 115, 425–444 (1992).
Stoerig, P. & Barth, E. Low-level phenomenal vision despite unilateral destruction of primary visual cortex. Conscious. Cogn. 10, 574–587 (2001).
Stoerig, P. & Cowey, A. Blindsight in man and monkey. Brain 120, 535–559 (1997).
Stoerig, P., Zontanou, A. & Cowey, A. Aware or unaware: assessment of cortical blindness in four men and a monkey. Cereb. Cortex 12, 565–574 (2002).
Cowey, A. & Stoerig, P. Blindsight in monkeys. Nature 373, 247–249 (1995). A compelling behavioural demonstration that monkeys with striate lesions lack awareness for items they can discriminate under forced-choice conditions.
Azzopardi, P. & Cowey, A. Blindsight and visual awareness. Conscious. Cogn. 7, 292–311 (1998).
Barbur, J. L., Watson, J. D., Frackowiak, R. S. & Zeki, S. Conscious visual perception without V1. Brain 116, 1293–1302 (1993).
Riddoch, G. Dissociation of visual perceptions due to occipital injuries, with especial reference to appreciation of movement. Brain 40, 15–57 (1917).
Weiskrantz, L., Cowey, A. & Hodinott-Hill, I. Prime-sight in a blindsight subject. Nature Neurosci. 5, 101–102 (2002).
Faubert, J., Diaconu, V., Ptito, M. & Ptito, A. Residual vision in the blind field of hemidecorticated humans predicted by a diffusion scatter model and selective spectral absorption of the human eye. Vision Res. 39, 149–157 (1999).
Girard, P., Salin, P. A. & Bullier, J. Visual activity in areas V3a and V3 during reversible inactivation of area V1 in the macaque monkey. J. Neurophysiol. 66, 1493–1503 (1991).
Rodman, H. R., Gross, C. G. & Albright, T. D. Afferent basis of visual response properties in area MT of the macaque. I. Effects of striate cortex removal. J. Neurosci. 9, 2033–2050 (1989).
Moore, T., Rodman, H. R., Repp, A. B. & Gross, C. G. Localization of visual stimuli after striate cortex damage in monkeys: parallels with human blindsight. Proc. Natl Acad. Sci. USA 92, 8215–8218 (1995).
Goebel, R., Muckli, L., Zanella, F. E., Singer, W. & Stoerig, P. Sustained extrastriate cortical activation without visual awareness revealed by fMRI studies of hemianopic patients. Vision Res. 41, 1459–1474 (2001).
Merigan, W. H., Nealey, T. A. & Maunsell, J. H. Visual effects of lesions of cortical area V2 in macaques. J. Neurosci. 13, 3180–3191 (1993).
Zihl, J., von Cramon, D., Mai, N. & Schmid, C. Disturbance of movement vision after bilateral posterior brain damage. Further evidence and follow up observations. Brain 114, 2235–2252 (1991).
Zihl, J., von Cramon, D. & Mai, N. Selective disturbance of movement vision after bilateral brain damage. Brain 106, 313–340 (1983).
Plant, G. T., Laxer, K. D., Barbaro, N. M., Schiffman, J. S. & Nakayama, K. Impaired visual motion perception in the contralateral hemifield following unilateral posterior cerebral lesions in humans. Brain 116, 1303–1335 (1993).
Pasternak, T. & Merigan, W. H. Motion perception following lesions of the superior temporal sulcus in the monkey. Cereb. Cortex 4, 247–259 (1994).
Meadows, J. C. Disturbed perception of colours associated with localized cerebral lesions. Brain 97, 615–632 (1974).
Zeki, S. A century of cerebral achromatopsia. Brain 113, 1721–1777 (1990).
Wade, A. R., Brewer, A. A., Rieger, J. W. & Wandell, B. A. Functional measurements of human ventral occipital cortex: retinotopy and colour. Phil. Trans. R. Soc. Lond. B 357, 963–973 (2002). | PubMed
Hadjikhani, N., Liu, A. K., Dale, A. M., Cavanagh, P. & Tootell, R. B. Retinotopy and color sensitivity in human visual cortical area V8. Nature Neurosci. 1, 235–241 (1998).
Heywood, C. & Cowey, A. With color in mind. Nature Neurosci. 1, 171–173 (1998).
Gross, C. G. How inferior temporal cortex became a visual area. Cereb. Cortex 5, 455–469 (1994).
Meadows, J. C. The anatomical basis of prosopagnosia. J. Neurol. Neurosurg. Psychiatry 37, 489–501 (1974).
Vallar, G. & Perani, D. The anatomy of unilateral neglect after right-hemisphere stroke lesions. A clinical/CT-scan correlation study in man. Neuropsychologia 24, 609–622 (1986).
Karnath, H. O., Ferber, S. & Himmelbach, M. Spatial awareness is a function of the temporal not the posterior parietal lobe. Nature 411, 950–953 (2001).
Balint, R. Psychic paralysis of gaze, optic ataxia, and spatial disorder of attention. Cogn. Neuropsychol. 12, 265–281 (1995).
Andersen, R. A. & Buneo, C. A. Intentional maps in posterior parietal cortex. Annu. Rev. Neurosci. 25, 189–220 (2002).
Watson, R. T., Valenstein, E., Day, A. & Heilman, K. M. Posterior neocortical systems subserving awareness and neglect. Neglect associated with superior temporal sulcus but not area 7 lesions. Arch. Neurol. 51, 1014–1021 (1994).
Blake, R. & Logothetis, N. K. Visual competition. Nature Rev. Neurosci. 3, 13–21 (2002).
Wheatstone, C. Contributions to the physiology of vision. Part I. On some remarkable, and hitherto unobserved, phenomena of binocular vision. Phil. Trans. R. Soc. Lond. B 128, 371–394 (1838)
Lansing, R. W. Electroencephalographic correlates of binocular rivalry in man. Science 146, 1325–1327 (1964). The first study to identify a neural correlate of awareness during binocular rivalry by using EEG to measure occipital responses.
Cobb, W. A., Morton, H. B. & Ettlinger, G. Cerebral potential evoked by pattern reversal and their suppression in visual rivalry. Nature 216, 1123–1125 (1967).
Logothetis, N. K. & Schall, J. D. Neuronal correlates of subjective visual perception. Science 245, 761–763 (1989). The first of a series of influential studies recording single-unit activity in monkeys that reported their perceptions during rivalry (see also references 65 and 66).
Leopold, D. A. & Logothetis, N. K. Activity changes in early visual cortex reflect monkeys' percepts during binocular rivalry. Nature 379, 549–553 (1996).
Sheinberg, D. L. & Logothetis, N. K. The role of temporal cortical areas in perceptual organization. Proc. Natl Acad. Sci. USA 94, 3408–3413 (1997).
Blake, R. A neural theory of binocular rivalry. Psychol. Rev. 96, 145–167 (1989).
Tong, F. & Engel, S. A. Interocular rivalry revealed in the human cortical blind-spot representation. Nature 411, 195–199 (2001).
Polonsky, A., Blake, R., Braun, J. & Heeger, D. J. Neuronal activity in human primary visual cortex correlates with perception during binocular rivalry. Nature Neurosci. 3, 1153–1159 (2000).
Tong, F. Competing theories of binocular rivalry: a possible resolution. Brain Mind 2, 55–83 (2001).
Tong, F., Nakayama, K., Vaughan, J. T. & Kanwisher, N. Binocular rivalry and visual awareness in human extrastriate cortex. Neuron 21, 753–759 (1998). The first fMRI study to demonstrate a tight coupling between cortical activity and the contents of human visual awareness during rivalry (see also references 68, 69 and 72).
Lumer, E. D., Friston, K. J. & Rees, G. Neural correlates of perceptual rivalry in the human brain. Science 280, 1930–1934 (1998).
Zipser, K., Lamme, V. A. & Schiller, P. H. Contextual modulation in primary visual cortex. J. Neurosci. 16, 7376–7389 (1996).
Rossi, A. F., Desimone, R. & Ungerleider, L. G. Contextual modulation in primary visual cortex of macaques. J. Neurosci. 21, 1698–1709 (2001).
Super, H., Spekreijse, H. & Lamme, V. A. Two distinct modes of sensory processing observed in monkey primary visual cortex (V1). Nature Neurosci. 4, 304–310 (2001).
Lee, T. S., Yang, C. F., Romero, R. D. & Mumford, D. Neural activity in early visual cortex reflects behavioral experience and higher-order perceptual saliency. Nature Neurosci. 5, 589–597 (2002). A single-unit study showing that V1 activity in the monkey reflects the perceptual salience of a target during visual search and can predict performance accuracy.
Ress, D., Nadell, D. E. & Heeger, D. J. Neural correlates of threshold visual pattern detection. Soc. Neurosci. Abstr. 783.7 (2001).
Ress, D., Backus, B. T. & Heeger, D. J. Activity in primary visual cortex predicts performance in a visual detection task. Nature Neurosci. 3, 940–945 (2000). An elegant fMRI study showing that attentional modulation levels in V1 can predict near-threshold detection performance.
Grunewald, A., Bradley, D. C. & Andersen, R. A. Neural correlates of structure-from-motion perception in macaque V1 and MT. J. Neurosci. 22, 6195–6207 (2002).
Sterzer, P., Russ, M. O., Preibisch, C. & Kleinschmidt, A. Neural correlates of spontaneous direction reversals in ambiguous apparent visual motion. Neuroimage 15, 908–916 (2002).
Muckli, L. et al. Apparent motion: event-related functional magnetic resonance imaging of perceptual switches and states. J. Neurosci. 22, RC219 (2002).
Murray, S. O., Kersten, D., Olshausen, B. A., Schrater, P. & Woods, D. L. Shape perception reduces activity in human primary visual cortex. Proc. Natl Acad. Sci. USA 99, 15164–15169 (2002).
Kleinschmidt, A., Buchel, C., Zeki, S. & Frackowiak, R. S. Human brain activity during spontaneously reversing perception of ambiguous figures. Proc. R. Soc. Lond. B 265, 2427–2433 (1998).
Schoups, A., Vogels, R., Qian, N. & Orban, G. Practising orientation identification improves orientation coding in V1 neurons. Nature 412, 549–553 (2001).
Rossi, A. F. & Paradiso, M. A. Neural correlates of perceived brightness in the retina, lateral geniculate nucleus, and striate cortex. J. Neurosci. 19, 6145–6156 (1999).
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).
Sugita, Y. Grouping of image fragments in primary visual cortex. Nature 401, 269–272 (1999).
von der Heydt, R., Peterhans, E. & Baumgartner, G. Illusory contours and cortical neuron responses. Science 224, 1260–1262 (1984).
Grosof, D. H., Shapley, R. M. & Hawken, M. J. Macaque V1 neurons can signal 'illusory' contours. Nature 365, 550–552 (1993).
Fiorani, M., Rosa, M. G. P., Gattass, R. & Rocha-Miranda, C. E. Dynamic surrounds of receptive fields in primate striate cortex: a physiological basis for perceptual completion? Neurobiology 89, 8547–8551 (1992). | PubMed |
Gilbert, C. D. & Wiesel, T. N. Receptive field dynamics in adult primary visual cortex. Nature 356, 150–152 (1992).
de Weerd, P., Gattass, R., Desimone, R. & Ungerleider, L. G. Responses of cells in monkey visual cortex during perceptual filling-in of an artificial scotoma. Nature 377, 731–734 (1995).
Hammond, P., Mouat, G. S. & Smith, A. T. Motion after-effects in cat striate cortex elicited by moving gratings. Exp. Brain Res. 60, 411–416 (1985).
Dragoi, V., Rivadulla, C. & Sur, M. Foci of orientation plasticity in visual cortex. Nature 411, 80–86 (2001).
Engel, S. A. & Furmanski, C. S. Selective adaptation to color contrast in human primary visual cortex. J. Neurosci. 21, 3949–3954 (2001).
Sengpiel, F. & Blakemore, C. Interocular control of neuronal responsiveness in cat visual cortex. Nature 368, 847–850 (1994).
Macknik, S. L. & Livingstone, M. S. Neuronal correlates of visibility and invisibility in the primate visual system. Nature Neurosci. 1, 144–149 (1998).
Schiller, P. H. Single unit analysis of backward visual masking and metacontrast in the cat lateral geniculate nucleus. Vision Res. 8, 855–866 (1968).
Gur, M. & Snodderly, D. M. A dissociation between brain activity and perception: chromatically opponent cortical neurons signal chromatic flicker that is not perceived. Vision Res. 37, 377–382 (1997).
He, S. & MacLeod, D. I. Orientation-selective adaptation and tilt after-effect from invisible patterns. Nature 411, 473–476 (2001). An original psychophysical study showing orientation-specific adaptation for high spatial frequency gratings that are too fine to be perceived, indicating that some amount of V1 processing can occur without awareness.
Blake, R. & Fox, R. Adaptation to invisible gratings and the site of binocular rivalry suppression. Nature 249, 488–490 (1974).
Nakamura, R. K. & Mishkin, M. Chronic 'blindness' following lesions of nonvisual cortex in the monkey. Exp. Brain Res. 63, 173–184 (1984).
Rees, G. et al. Unconscious activation of visual cortex in the damaged right hemisphere of a parietal patient with extinction. Brain 123, 1624–1633 (2000).
Vuilleumier, P. et al. Neural fate of seen and unseen faces in visuospatial neglect: a combined event-related functional MRI and event-related potential study. Proc. Natl Acad. Sci. USA 98, 3495–3500 (2001).
Dehaene, S. et al. Cerebral mechanisms of word masking and unconscious repetition priming. Nature Neurosci. 4, 752–758 (2001).
Beck, D. M., Rees, G., Frith, C. D. & Lavie, N. Neural correlates of change detection and change blindness. Nature Neurosci. 4, 645–650 (2001).
Ffytche, D. H. et al. The anatomy of conscious vision: an fMRI study of visual hallucinations. Nature Neurosci. 1, 738–742 (1998).
Braun, A. R. et al. Dissociated pattern of activity in visual cortices and their projections during human rapid eye movement sleep. Science 279, 91–95 (1998).
Hadjikhani, N. et al. Mechanisms of migraine aura revealed by functional MRI in human visual cortex. Proc. Natl Acad. Sci. USA 98, 4687–4692 (2001).
Nunn, J. A. et al. Functional magnetic resonance imaging of synesthesia: activation of V4/V8 by spoken words. Nature Neurosci. 5, 371–375 (2002).
Aleman, A., Rutten, G. J., Sitskoorn, M. M., Dautzenberg, G. & Ramsey, N. F. Activation of striate cortex in the absence of visual stimulation: an fMRI study of synesthesia. Neuroreport 12, 2827–2830 (2001).
Kosslyn, S. M., Ganis, G. & Thompson, W. L. Neural foundations of imagery. Nature Rev. Neurosci. 2, 635–642 (2001).
Foerster, O. Beiträge zur Pathophysiologie der Sehbahn und der Sehsphäre. J. Psychol. Neurol. 39, 463–485 (1929).
Dobelle, W. H. & Mladejovsky, M. G. Phosphenes produced by electrical stimulation of human occipital cortex, and their application to the development of a prosthesis for the blind. J. Physiol. (Lond.) 243, 553–576 (1974).
Brindley, G. S. & Lewin, W. S. The sensations produced by electrical stimulation of the visual cortex. J. Physiol. (Lond.) 196, 479–493 (1968).
Salzman, C. D., Britten, K. H. & Newsome, W. T. Cortical microstimulation influences perceptual judgements of motion direction. Nature 346, 174–177 (1990). A classic study showing that a monkey's perceptual interpretation of ambiguous motion can be biased by electrical stimulation in area MT.
Cowey, A. & Walsh, V. Magnetically induced phosphenes in sighted, blind and blindsighted observers. Neuroreport 11, 3269–3273 (2000).
Girard, P., Hupe, J. M. & Bullier, J. Feedforward and feedback connections between areas V1 and V2 of the monkey have similar rapid conduction velocities. J. Neurophysiol. 85, 1328–1331 (2001).
Movshon, J. A. & Newsome, W. T. Visual response properties of striate cortical neurons projecting to area MT in macaque monkeys. J. Neurosci. 16, 7733–7741 (1996).
Penfield, W. The Cerebral Cortex of Man: a Clinical Study of Localization of Function (Macmillan, New York, 1950).
Amassian, V. E. et al. Suppression of visual perception by magnetic coil stimulation of human occipital cortex. Electroencephalogr. Clin. Neurophysiol. 74, 458–462 (1989).
Kamitani, Y. & Shimojo, S. Manifestation of scotomas created by transcranial magnetic stimulation of human visual cortex. Nature Neurosci. 2, 767–771 (1999).
Corthout, E., Uttl, B., Walsh, V., Hallett, M. & Cowey, A. Timing of activity in early visual cortex as revealed by transcranial magnetic stimulation. Neuroreport 10, 2631–2634 (1999).
Beckers, G. & Homberg, V. Cerebral visual motion blindness: transitory akinetopsia induced by transcranial magnetic stimulation of human area V5. Proc. R. Soc. Lond. B 249, 173–178 (1992).
Pascual-Leone, A. & Walsh, V. Fast backprojections from the motion to the primary visual area necessary for visual awareness. Science 292, 510–512 (2001). An innovative TMS study that tested whether feedback projections from MT to V1 might be necessary for awareness of motion phosphenes.
di Lollo, V., Enns, J. T. & Rensink, R. A. Competition for consciousness among visual events: the psychophysics of reentrant visual processes. J. Exp. Psychol. Gen. 129, 481–507 (2000). | PubMed
Breitmeyer, B. G. Visual Masking: an Integrative Approach (Clarendon, Oxford, 1984).
Colombo, M., Colombo, A. & Gross, C. G. Bartolomeo Panizza's Observations on the optic nerve (1855). Brain Res. Bull. 58, 529–539 (2002).
Ferrier, D. Functions of the Brain (Smith, Elder & Co., London, 1876).
Munk, H. translated in von Bonin, G. Some Papers on the Cerebral Cortex (Thomas, Springfield, Illinois, 1960).
Henschen, S. E. On the visual path and centre. Brain 16, 170–180 (1893).
He, S., Cavanagh, P. & Intriligator, J. Attentional resolution and the locus of visual awareness. Nature 383, 334–337 (1996).
Motter, B. C. Focal attention produces spatially selective processing in visual cortical areas V1, V2, and V4 in the presence of competing stimuli. J. Neurophysiol. 70, 909–919 (1993).
Moran, J. & Desimone, R. Selective attention gates visual processing in the extrastriate cortex. Science 229, 782–784 (1985).
Vidyasagar, T. R. Gating of neuronal responses in macaque primary visual cortex by an attentional spotlight. Neuroreport 9, 1947–1952 (1998).
Ito, M. & Gilbert, C. D. Attention modulates contextual influences in the primary visual cortex of alert monkeys. Neuron 22, 593–604 (1999).
Roelsema, P. R., Lamme, V. A. & Spekreijse, H. Object-based attention in the primary visual cortex of the macaque monkey. Nature 395, 376–381 (1998). A compelling demonstration of object-based attention effects in V1 of the monkey.
Mehta, A. D., Ulbert, I. & Schroeder, C. E. Intermodal selective attention in monkeys. I: distribution and timing of effects across visual areas. Cereb. Cortex 10, 343–358 (2000).
Watanabe, T. et al. Task-dependent influences of attention on the activation of human primary visual cortex. Proc. Natl Acad. Sci. USA 95, 11489–11492 (1998).
Gandhi, S. P., Heeger, D. J. & Boynton, G. M. Spatial attention affects brain activity in human primary visual cortex. Proc. Natl Acad. Sci. USA 96, 3314–3319 (1999).
Brefczynski, J. A. & DeYoe, E. A. A physiological correlate of the 'spotlight' of visual attention. Nature Neurosci. 2, 370–374 (1999).
Somers, D. C., Dale, A. M., Seiffert, A. E. & Tootell, R. B. Functional MRI reveals spatially specific attentional modulation in human primary visual cortex. Proc. Natl Acad. Sci. USA 96, 1663–1668 (1999).
Saenz, M., Buracas, G. T. & Boynton, G. M. Global effects of feature-based attention in human visual cortex. Nature Neurosci. 5, 631–632 (2002).
O'Connor, D. H., Fukui, M. M., Pinsk, M. A. & Kastner, S. Attention modulates responses in the human lateral geniculate nucleus. Nature Neurosci. 15, 1203–1209 (2002). | PubMed
Vanduffel, W., Tootell, R. B. & Orban, G. A. Attention-dependent suppression of metabolic activity in the early stages of the macaque visual system. Cereb. Cortex 10, 109–126 (2000).
I would like to thank C. Gross, S. Kastner, T. Moore and A. Seiffert for helpful comments on this manuscript. This work was supported by the National Institutes of Health, James S. McDonnell Foundation and Pew Charitable Trusts.
Encyclopedia of Life Sciences
MIT Encyclopedia of Cognitive Science
- PRIMARY VISUAL CORTEX
The first cortical area to receive inputs from the eye via the geniculostriate pathway; also referred to as V1, area 17 and striate cortex.
- EXTRASTRIATE CORTEX
A belt of visually responsive areas of cortex surrounding the primary visual cortex.
- MT AND MST
Motion sensitive areas of extrastriate cortex.
- PO AND PIP
The parieto-occipital (PO) and posterior intraparietal (PIP) visual areas lie in the dorsal stream and have weak reciprocal connections with V1. Their specific functions are not well understood.
This visual area lies anterior to MT and MST in the floor of the superior temporal sulcus, and is also involved in motion perception but has not been extensively studied.
The superior temporal polysensory area contains neurons that respond to visual, auditory and somatosensory stimuli, and responds strongly to visual motion.
- TOE AND TE
These areas comprise the posterior and anterior portions of inferotemporal cortex (IT) respectively, and are involved in shape, object and face processing.
This visual area lies in the parahippocampal gyrus, which has been implicated in scene perception and visual memory.
The lateral intraparietal area (LIP) is strongly implicated in visual-spatial attention and eye movement planning.
- FRONTAL EYE FIELDS
(FEF). These areas are strongly implicated in visual–spatial attention and eye movement planning, and have strong connections with area LIP.
- DORSAL STREAM
Visual brain areas that are involved in the localization of objects and are mostly found in the posterior/superior part of the brain.
- VENTRAL STREAM
Visual brain areas that are involved in the identification of objects and are mostly found in the posterior/inferior part of the brain.
- BACKWARD VISUAL MASKING
The reduced perception that occurs when a weak or brief stimulus is followed immediately by a stronger stimulus.
An unusual 'mixing of the senses' in which a stimulus in one sensory modality (for example, a sound) elicits a percept in another modality (such as visual perception of a colour).
Loss of vision over half of the visual field, typically resulting from damage to the optic radiations that project to V1 or damage to V1 itself.
- MOTION PHOSPHENES
Moving visual images that can be induced by stimulating parts of the visual system that are sensitive to motion.
- ORTHODROMIC ACTIVATION
Activation of a target neuron by stimulation of an input neuron that synapses onto the target; action potentials are propagated in the normal direction along the input axon.
- TRANSCRANIAL MAGNETIC STIMULATION
(TMS). A technique that is used to induce a transient interruption of normal activity in a relatively restricted area of the brain. It is based on the generation of a strong magnetic field near the area of interest, which, if changed rapidly enough, will induce an electric field that is sufficient to stimulate neurons.
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