Micro-consciousness
Micro-consciousness is a neurobiological theory of consciousness proposed by Semir Zeki.[1]. The theory argues that phenomenal consciousness consists of many micro-consciousnesses that are distributed in space and time[2]. Therefore, there is no unity of consciousness at the level of phenomenal consciousness[3]. Rather, consciousness is distributed in space and in time because different phenomenal components are processed in different locations and at different temporalities. This, however, is not noticeable in day-to-day life – the several micro-conscious components that occur together are perceived as one on a macroscale, i.e., in macro-consciousness.
Various empirical observations led to the formulation of the theory of micro-consciousness. First, is the fact that different parts of the visual brain perform different functions; that is, there is functional specialization within the brain. This is clearly demonstrated not only through physiological[4] and human imaging[5][6][7][8], which show that different cardinal visual features are processed in anatomically different parts, with visual motion being processed in V5/MT and color vision in V4 LOC.
Second, these processing areas also appear to be perceptual areas. Continuing with the previous examples, this argument is demonstrated by clinical evidence showing that lesions in V4 lead to cerebral achromatopsia (the inability to perceive color)[9], whereas cerebral akinetopsia (the inability to perceive motion)[10] is produced by lesions in V5. Moreover, when V5 is disconnected from V1, following lesions to V1, the subject may still be able to perceive visual motion consciously, even though the motion is only described in terms of moving 'shadows', which is known as the Riddoch Syndrome. These clinical observations show that the conscious experience of a particular visual feature is disrupted when there is damage to the relevant, specialized area, whereas conscious vision remains when the area is intact but other visual areas of the cortex are damaged, in particular area V1, as long as the connections between the subcortex and the specialized area remain intact.
Third, there is the phenomenon of perceptual asynchrony. Functional specialization raises the question of how the various features are bound together to give the experience of the world as a unified whole. Some theories of consciousness posit that binding between visual features is the prelude to conscious experience of the visual stimulus. But psychophysical experiments have demonstrated that we do not see all visual features at the exact same time. Consequently, subjects mis-bind visual features that occur together in real time[11][12][13][14][15][16]. This demonstrates that the brain processes information asynchronously, that is, brain areas do not wait for other brain areas to complete the information processing[17]. These results seem to suggest that binding may not occur by physiological interaction between cells, as is commonly assumed, but through some other mechanism. This also derives from the observations that mis-binds two simultaneously presented attributes as the perceptual asynchrony experiments demonstrate, and only binds together information that has been processed and reached a conscious correlate[1].
Although the theory of micro-consciousness argues that different areas can acquire a conscious correlate, it does not claim that no other areas are involved. But certain propositions can be eliminated, such as the proposal that conscious experience of visual motion requires return input from V5 to V1[18]. Micro-consciousness versus macro-consciousness
Micro-consciousness versus macro-consciousness
Inspired by the world of physics, which is divided into macro-physics, that is to say, gravitational physics and general relativity, and micro-physics, that is to say quantum physics, the demonstration of micro-consciousness raises an interesting issue, related in particular to neural binding. It is common knowledge that in our normal experience we perceive different features of an object as being completely bound. However, the perceptual asynchrony experiments show us that this is not the case at very short timescales after the appearance of a stimulus, say less than about 150 ms. This has led to the proposal that maybe the perceptual world in vision should also be considered as consisting of two separate worlds, the micro-perceptive and macro-perceptive world, the former being one in which features are not bound or mis-bound, and the latter one in which they are completely bound. This raises the question of how and when the transition from the world of micro-perception to that of macro-perception occurs. It is of crucial importance in understanding the problem of neural binding, and there is at least a superficial similarity to the transition from the world of microphysics to that of macrophysics. With this difference that the latter transition occurred billions of years ago, starting with the big bang, whereas the transition from the micro- to the macro-perceptive world, assuming that there is a transition, occurs at all times[19]
References
- ↑ 1.0 1.1 Zeki, S.; Bartels, A. (1999-06-01). "Toward a Theory of Visual Consciousness". Consciousness and Cognition. 8 (2): 225–259. doi:10.1006/ccog.1999.0390. ISSN 1053-8100. PMID 10448004. Unknown parameter
|s2cid=ignored (help) - ↑ Zeki, Semir (2007), "A Theory of Micro-Consciousness", The Blackwell Companion to Consciousness, John Wiley & Sons, Ltd, pp. 580–588, doi:10.1002/9780470751466.ch46, ISBN 978-0-470-75146-6, retrieved 2021-04-27
- ↑ Zeki, S. (May 2003). "The disunity of consciousness". Trends in Cognitive Sciences. 7 (5): 214–218. doi:10.1016/s1364-6613(03)00081-0. ISSN 1364-6613. PMID 12757823. Unknown parameter
|s2cid=ignored (help) - ↑ Zeki, S. M. (1978-08-XX). "Functional specialisation in the visual cortex of the rhesus monkey". Nature. 274 (5670): 423–428. Bibcode:1978Natur.274..423Z. doi:10.1038/274423a0. ISSN 1476-4687. PMID 97565. Unknown parameter
|s2cid=ignored (help); Check date values in:|date=(help) - ↑ Zeki, S.; Watson, J. D.; Lueck, C. J.; Friston, K. J.; Kennard, C.; Frackowiak, R. S. (1991-03-01). "A direct demonstration of functional specialization in human visual cortex". Journal of Neuroscience. 11 (3): 641–649. doi:10.1523/JNEUROSCI.11-03-00641.1991. ISSN 0270-6474. PMC 6575357 Check
|pmc=value (help). PMID 2002358. - ↑ Wade, A.; Augath, M.; Logothetis, N.; Wandell, B. (2008-09-01). "fMRI measurements of color in macaque and human". Journal of Vision. 8 (10): 6.1–19. doi:10.1167/8.10.6. ISSN 1534-7362. PMC 3045694. PMID 19146348.
- ↑ Brouwer, Gijs Joost; Heeger, David J. (2009-11-04). "Decoding and Reconstructing Color from Responses in Human Visual Cortex". Journal of Neuroscience. 29 (44): 13992–14003. doi:10.1523/JNEUROSCI.3577-09.2009. ISSN 0270-6474. PMC 2799419. PMID 19890009.
- ↑ Lafer-Sousa, Rosa; Conway, Bevil R.; Kanwisher, Nancy G. (2016-02-03). "Color-Biased Regions of the Ventral Visual Pathway Lie between Face- and Place-Selective Regions in Humans, as in Macaques". Journal of Neuroscience. 36 (5): 1682–1697. doi:10.1523/JNEUROSCI.3164-15.2016. ISSN 0270-6474. PMC 4737777. PMID 26843649.
- ↑ ZEKI, S. (1990-12-01). "A Century of Cerebral Achromatopsia". Brain. 113 (6): 1721–1777. doi:10.1093/brain/113.6.1721. ISSN 0006-8950. PMID 2276043.
- ↑ ZEKI, S. (1991-04-01). "Cerebral Akinetopsia (Visual Motion Blindness)". Brain. 114 (2): 811–824. doi:10.1093/brain/114.2.811. ISSN 0006-8950. PMID 2043951.
- ↑ Moutoussis, K.; Zeki, S. (1997-03-22). "A direct demonstration of perceptual asynchrony in vision". Proceedings of the Royal Society of London. Series B: Biological Sciences. 264 (1380): 393–399. Bibcode:1997RSPSB.264..393M. doi:10.1098/rspb.1997.0056. PMC 1688275. PMID 9107055.
- ↑ Arnold, Derek H; Clifford, Colin W.G (2002-03-22). "Determinants of asynchronous processing in vision". Proceedings of the Royal Society of London. Series B: Biological Sciences. 269 (1491): 579–583. doi:10.1080/13506280802340653. PMC 1690936. PMID 11916473.
- ↑ Viviani, Paolo; Aymoz, Christelle (2001-10-01). "Colour, form, and movement are not perceived simultaneously". Vision Research. 41 (22): 2909–2918. doi:10.1016/S0042-6989(01)00160-2. ISSN 0042-6989. PMID 11701183. Unknown parameter
|s2cid=ignored (help) - ↑ Self, Eriko (2014-11-XX). "Color–motion asynchrony assessed along the chromatic axes and with luminance variation". Attention, Perception, & Psychophysics. 76 (8): 2184–2188. doi:10.3758/s13414-014-0773-5. ISSN 1943-3921. PMID 25280522. Unknown parameter
|s2cid=ignored (help); Check date values in:|date=(help) - ↑ Holcombe, Alex O. (2009-01-XX). "Temporal binding favours the early phase of colour changes, but not of motion changes, yielding the colour–motion asynchrony illusion". Visual Cognition. 17 (1–2): 232–253. doi:10.1080/13506280802340653. ISSN 1350-6285. Unknown parameter
|s2cid=ignored (help); Check date values in:|date=(help) - ↑ Lo, Yu Tung; Zeki, Semir (2014). "Perceptual asynchrony for motion". Frontiers in Human Neuroscience. 8: 108. doi:10.3389/fnhum.2014.00108. ISSN 1662-5161. PMC 3941194. PMID 24624071.
- ↑ Zeki, Semir (2015-05-19). "A massively asynchronous, parallel brain". Philosophical Transactions of the Royal Society B: Biological Sciences. 370 (1668): 20140174. doi:10.1098/rstb.2014.0174. PMC 4387515. PMID 25823871.
- ↑ Lamme, Victor A.F. (2001-04-01). "Blindsight: the role of feedforward and feedback corticocortical connections". Acta Psychologica. 107 (1–3): 209–228. doi:10.1016/S0001-6918(01)00020-8. ISSN 0001-6918. PMID 11388136.
- ↑ Zeki, Semir (2020). ""Multiplexing" cells of the visual cortex and the timing enigma of the binding problem". European Journal of Neuroscience. 52 (12): 4684–4694. doi:10.1111/ejn.14921. ISSN 1460-9568. PMID 32722893 Check
|pmid=value (help). Unknown parameter|s2cid=ignored (help)
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