Neural correlates of consciousness: Progress and problems

Nature Reviews Neuroscience

Volumn 17, Issue 5, 2016, Pages 307-321

  Koch, Christof ^a   Massimini, Marcello ^b,c   Boly, Melanie ^d   Tononi, Giulio ^d  

^a ALLEN INSTITUTE FOR BRAIN SCIENCE   (United States)

^b UNIVERSITY OF MILAN   (Italy)

^c IRCCS FONDAZIONE DON CARLO GNOCCHI   (Italy)

^d UNIVERSITY OF WISCONSIN SCHOOL OF MEDICINE AND PUBLIC HEALTH   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

BASAL GANGLION; BRAIN CORTEX; BRAIN REGION; CELLS BY BODY ANATOMY; CONSCIOUSNESS; ELECTROENCEPHALOGRAM; EVENT RELATED POTENTIAL; FRONTOPARIETAL CORTEX; HUMAN; NERVE CELL; NERVE CELL DIFFERENTIATION; NEURAL CORRELATES OF CONSCIOUSNESS; NEUROANATOMY; NEUROPHYSIOLOGY; NONHUMAN; POSTERIOR CORTICAL HOT ZONE; PRIORITY JOURNAL; REVIEW; TASK PERFORMANCE; ANIMAL; BRAIN; NERVE TRACT; PHYSIOLOGY;

ANIMALS; BRAIN; CONSCIOUSNESS; HUMANS; NEURAL PATHWAYS; NEURONS;

EID: 84964397273     PISSN: 1471003X     EISSN: 14710048     Source Type: Journal    
DOI: 10.1038/nrn.2016.22     Document Type: Review

References (248)

1. Tononi, G. The integrated information theory of consciousness: an updated account. Arch. Ital. Biol. 150, 56-90 (2012
2. Posner, J. B., Saper, C. B., Schiff, N. D., & Plum, F. Plum and Posner's Diagnosis of Stupor and Coma (Oxford University Press, 2007
3. Rees, G., Kreiman, G., & Koch, C. Neural correlates of consciousness in humans. Nat. Rev. Neurosci. 3, 261-270 (2002
4. Faivre, N., Salomon, R., & Blanke, O. Visual consciousness and bodily self-consciousness. Curr. Opin. Neurol. 28, 23-28 (2015
5. Merrick, C., Godwin, C., Geisler, M., & Morsella, E. The olfactory system as the gateway to the neural correlates of consciousness. Front. Psychol. 4, 1011 (2014
6. Gallace, A., & Spence, C. The cognitive and neural correlates of 'tactile consciousness': a multisensory perspective. Conscious. Cogn. 17, 370-407 (2008
7. Fleming, S. M., & Dolan, R. J. The neural basis of metacognitive ability. Phil. Trans. R. Soc. B 367, 1338-1349 (2012
8. Laureys, S. The neural correlate of (un)awareness: lessons from the vegetative state. Trends Cogn. Sci. 9, 556-559 (2005
9. Giacino, J. T., Kalmar, K., & Whyte, J. The JFK Coma Recovery Scale - Revised: measurement characteristics and diagnostic utility. Arch. Phys. Med. Rehabil. 85, 2020-2029 (2004
10. Schnakers, C. et al. Diagnostic accuracy of the vegetative and minimally conscious state: clinical consensus versus standardized neurobehavioral assessment. BMC Neurol. 9, 35 (2009
11. Owen, A. M. et al. Detecting awareness in the vegetative state. Science 313, 1402 (2006
12. Kunimoto, C., Miller, J., & Pashler, H. Confidence and accuracy of near-Threshold discrimination responses. Conscious. Cogn. 10, 294-340 (2001
13. Reingold, E. M., & Merikle, P. M. Using direct and indirect measures to study perception without awareness. Percept. Psychophys. 44, 563-575 (1988
14. Weiskrantz, L. Is blindsight just degraded normal vision?. Exp. Brain Res. 192, 413-416 (2009
15. Snodgrass, M., Bernat, E., & Shevrin, H. Unconscious perception: a model-based approach to method and evidence. Percept. Psychophys. 66, 846-867 (2004
16. Sandberg, K., Timmermans, B., Overgaard, M., & Cleeremans, A. Measuring consciousness: is one measure better than the other?. Conscious. Cogn. 19, 1069-1078 (2010
17. Del Cul, A., Baillet, S., & Dehaene, S. Brain dynamics underlying the nonlinear threshold for access to consciousness. PLoS Biol. 5, e260 (2007
18. Cowey, A., & Stoerig, P. Blindsight in monkeys. Nature 373, 247-249 (1995
19. Kepecs, A., Uchida, N., Zariwala, H. A., & Mainen, Z. F. Neural correlates, computation and behavioural impact of decision confidence. Nature 455, 227-231 (2008
20. Leopold, D. A. Primary visual cortex: awareness and blindsight. Annu. Rev. Neurosci. 35, 91-109 (2012
21. Crick, F., & Koch, C. Towards a neurobiological theory of consciousness. Semin. Neurosci. 2, 263-275 (1990
22. Koch, C The Quest for Consciousness: a Neurobiological Approach (Roberts, 2004
23. Baars, B. A. Cognitive Theory of Consciousness (Cambridge Univ. Press, 1988
24. Blake, R., & Logothetis, N. K. Visual competition. Nat. Rev. Neurosci. 3, 13-21 (2002
25. Tsuchiya, N., & Koch, C. Continuous flash suppression reduces negative afterimages. Nat. Neurosci. 8, 1096-1101 (2005
26. Imamoglu, F., Kahnt, T., Koch, C., & Haynes, J. D. Changes in functional connectivity support conscious object recognition. Neuroimage 63, 1909-1917 (2012
27. Breitmeyer, B. G., & Ögmen, H. Recent models and findings in visual backward masking: a comparison, review, and update. Percept. Psychophys. 62, 1572-1595 (2000
28. Francis, G. Quantitative theories of metacontrast masking. Psychol. Rev. 107, 768-785 (2000
29. Koivisto, M., & Revonsuo, A. Event-related brain potential correlates of visual awareness. Neurosci. Biobehav. Rev. 34, 922-934 (2010
30. Miller, S. M. Closing in on the constitution of consciousness. Front. Psychol. 5, 1293 (2014
31. Aru, J., Bachmann, T., Singer, W., & Melloni, L. Distilling the neural correlates of consciousness. Neurosci. Biobehav. Rev. 36, 737-746 (2012
32. de Graaf, T. A., Hsieh, P. J., & Sack, A. T. The 'correlates' in neural correlates of consciousness. Neurosci. Biobehav. Rev. 36, 191-197 (2012
33. Aru, J. et al. Local category-specific gamma band responses in the visual cortex do not reflect conscious perception. J. Neurosci. 32, 14909-14914 (2012
34. Pitts, M. A., Metzler, S., & Hillyard, S. A. Isolating neural correlates of conscious perception from neural correlates of reporting one's perception. Front. Psychol. 5, 1078 (2014
35. Tsuchiya, N., Wilke, M., Frässle, S., & Lamme, V. A. No report paradigms: extracting the true neural correlates of consciousness. Trends Cogn. Sci. 19, 757-770 (2015
36. Frässle, S., Sommer, J., Jansen, A., Naber, M., & Einhäuser, W. Binocular rivalry: frontal activity relates to introspection and action but not to perception. J. Neurosci. 34, 1738-1747 (2014
37. Maquet, P. et al. Functional neuroanatomy of human slow wave sleep. J. Neurosci. 17, 2807-2812 (1997
38. Massimini, M. et al. Breakdown of cortical effective connectivity during sleep. Science 309, 2228-2232 (2005
39. Alkire, M. T., Hudetz, A. G., & Tononi, G. Consciousness and anesthesia. Science 322, 876-880 (2008
40. Brown, E. N., Lydic, R., & Schiff, N. D. General anesthesia, sleep, and coma. N. Engl. J. Med. 363, 2638-2650 (2010
41. Laureys, S., Owen, A. M., & Schiff, N. D. Brain function in coma, vegetative state, and related disorders. Lancet Neurol. 3, 537-546 (2004
42. Gosseries, O., Di, H., Laureys, S., & Boly, M. Measuring consciousness in severely damaged brains. Annu. Rev. Neurosci. 37, 457-478 (2014
43. Hohwy, J. The neural correlates of consciousness: new experimental approaches needed?. Conscious. Cogn. 18, 428-438 (2009
44. Siclari, F., LaRocque, J. J., Bernardi, G., Postle, B. R., & Tononi, G. The neural correlates of consciousness in sleep: a no task, within-state paradigm. Preprint at http://biorxiv.org/content/early/2014/12/30/012443 (2014
45. Herculano-Houzel, S. The remarkable, yet not extraordinary, human brain as a scaled up primate brain and its associated cost. Proc. Natl Acad. Sci. USA 109 (Suppl. 1), 10661-10668 (2012
46. Baumann, O. et al. Consensus paper: the role of the cerebellum in perceptual processes. Cerebellum 14, 197-220 (2015
47. Lemon, R. N., & Edgley, S. A. Life without a cerebellum. Brain 133, 652-654 (2010
48. Yu, F., Jiang, Q. J., Sun, X. Y., & Zhang, R. W. A new case of complete primary cerebellar agenesis: clinical and imaging findings in a living patient. Brain 138, e353 (2015
49. Moruzzi, G., & Magoun, H. W. Brain stem reticular formation and activation of the EEG. Electroencephalogr. Clin. Neurophysiol. 1, 455-473 (1949
50. Parvizi, J., & Damasio, A. R. Neuroanatomical correlates of brainstem coma. Brain 126, 1524-1536 (2003
51. Parvizi, J., & Damasio, A. Consciousness and the brainstem. Cognition 79, 135-160 (2001
52. Nir, Y. et al. Regional slow waves and spindles in human sleep. Neuron 70, 153-169 (2011
53. Brown, R. E., Basheer, R., McKenna, J. T., Strecker, R. E., & McCarley, R. W. Control of sleep and wakefulness. Physiol. Rev. 92, 1087-1187 (2012
54. Siclari, F., Larocque, J. J., Postle, B. R., & Tononi, G. Assessing sleep consciousness within subjects using a serial awakening paradigm. Front. Psychol. 4, 542 (2013
55. Bhatia, K. P., & Marsden, C. D. The behavioural and motor consequences of focal lesions of the basal ganglia in man. Brain 117, 859-876 (1994
56. Wijdicks, E. F., & Cranford, R. E. Clinical diagnosis of prolonged states of impaired consciousness in adults. Mayo Clin. Proc. 80, 1037-1046 (2005
57. Lutkenhoff, E. S. et al. Thalamic and extrathalamic mechanisms of consciousness after severe brain injury. Ann. Neurol. 78, 68-76 (2015
58. Jain, S. K. et al. Bilateral large traumatic basal ganglia haemorrhage in a conscious adult: a rare case report. Brain Inj. 27, 500-503 (2013
59. Straussberg, R. et al. Familial infantile bilateral striatal necrosis: clinical features and response to biotin treatment. Neurology 59, 983-989 (2002
60. Caparros-Lefebvre, D., Destee, A., & Petit, H. Late onset familial dystonia: could mitochondrial deficits induce a diffuse lesioning process of the whole basal ganglia system?. J. Neurol. Neurosurg. Psychiatry 63, 196-203 (1997
61. Alexander, G. E., DeLong, M. R., & Strick, P. L. Parallel organization of functionally segregated circuits linking basal ganglia and cortex. Annu. Rev. Neurosci. 9, 357-381 (1986
62. McHaffie, J. G., Stanford, T. R., Stein, B. E., Coizet, V., & Redgrave, P. Subcortical loops through the basal ganglia. Trends Neurosci. 28, 401-407 (2005
63. Torgerson, C. M., Irimia, A., Goh, S. Y., & Van Horn, J. D. The DTI connectivity of the human claustrum. Hum. Brain Mapp. 36, 827-838 (2015
64. Crick, F. C., & Koch, C. What is the function of the claustrum?. Phil. Trans. R. Soc. B 360, 1271-1279 (2005
65. Koubeissi, M. Z., Bartolomei, F., Beltagy, A., & Picard, F. Electrical stimulation of a small brain area reversibly disrupts consciousness. Epilepsy Behav. 37, 32-35 (2014
66. Damasio, A., Damasio, H., & Tranel, D. Persistence of feelings and sentience after bilateral damage of the insula. Cereb. Cortex 23, 833-846 (2013
67. Bogen, J. E. On the neurophysiology of consciousness: I. An overview. Conscious. Cogn. 4, 52-62 (1995
68. Van Der Werf, Y. D., Witter, M. P., & Groenewegen, H. J. The intralaminar and midline nuclei of the thalamus. Anatomical and functional evidence for participation in processes of arousal and awareness. Brain Res. Brain Res. Rev. 39, 107-140 (2002
69. Schiff, N. D. et al. Behavioural improvements with thalamic stimulation after severe traumatic brain injury. Nature 448, 600-603 (2007
70. Jones, E. G. A new view of specific and nonspecific thalamocortical connections. Adv. Neurol. 77, 49-71; discussion 72-73 (1998
71. Theyel, B. B., Llano, D. A., & Sherman, S. M. The corticothalamocortical circuit drives higher-order cortex in the mouse. Nat. Neurosci. 13, 84-88 (2010
72. Fuller, P. M., Sherman, D., Pedersen, N. P., Saper, C. B., & Lu, J. Reassessment of the structural basis of the ascending arousal system. J. Comp. Neurol. 519, 933-956 (2011
73. Laureys, S. et al. Cortical processing of noxious somatosensory stimuli in the persistent vegetative state. Neuroimage 17, 732-741 (2002
74. Lehky, S. R., & Maunsell, J. H. No binocular rivalry in the LGN of alert macaque monkeys. Vision Res. 36, 1225-1234 (1996
75. Wilke, M., Mueller, K. M., & Leopold, D. A. Neural activity in the visual thalamus reflects perceptual suppression. Proc. Natl Acad. Sci. USA 106, 9465-9470 (2009
76. Panagiotaropoulos, T. I., Kapoor, V., & Logothetis, N. K. Subjective visual perception: from local processing to emergent phenomena of brain activity. Phil. Trans. R. Soc. B 369, 20130534 (2014
77. Boly, M. et al. Connectivity changes underlying spectral EEG changes during propofol-induced loss of consciousness. J. Neurosci. 32, 7082-7090 (2012
78. Velly, L. J. et al. Differential dynamic of action on cortical and subcortical structures of anesthetic agents during induction of anesthesia. Anesthesiology 107, 202-212 (2007
79. Magnin, M. et al. Thalamic deactivation at sleep onset precedes that of the cerebral cortex in humans. Proc. Natl Acad. Sci. USA 107, 3829-3833 (2010
80. Crick, F., & Koch, C. Are we aware of neural activity in primary visual cortex?. Nature 375, 121-123 (1995
81. Silvanto, J. Is primary visual cortex necessary for visual awareness?. Trends Neurosci. 37, 618-619 (2014
82. Jiang, Y., Zhou, K., & He, S. Human visual cortex responds to invisible chromatic flicker. Nat. Neurosci. 10, 657-662 (2007
83. He, S., & MacLeod, D. I. Orientation-selective adaptation and tilt after-effect from invisible patterns. Nature 411, 473-476 (2001
84. Haynes, J. D., & Rees, G. Predicting the orientation of invisible stimuli from activity in human primary visual cortex. Nat. Neurosci. 8, 686-691 (2005
85. Logothetis, N. K. Single units and conscious vision. Phil. Trans. R. Soc. Lond. B 353, 1801-1818 (1998
86. Leopold, D. A., & Logothetis, N. K. Multistable phenomena: changing views in perception. Trends Cogn. Sci. 3, 254-264 (1999
87. Polonsky, A., Blake, R., Braun, J., & Heeger, D. J. Neuronal activity in human primary visual cortex correlates with perception during binocular rivalry. Nat. Neurosci. 3, 1153-1159 (2000
88. Lee, S. H., Blake, R., & Heeger, D. J. Traveling waves of activity in primary visual cortex during binocular rivalry. Nat. Neurosci. 8, 22-23 (2005
89. Harrison, S. A., & Tong, F. Decoding reveals the contents of visual working memory in early visual areas. Nature 458, 632-635 (2009
90. Donner, T. H., Sagi, D., Bonneh, Y. S., & Heeger, D. J. Opposite neural signatures of motion-induced blindness in human dorsal and ventral visual cortex. J. Neurosci. 28, 10298-10310 (2008
91. Weiskrantz, L. Blindsight revisited. Curr. Opin. Neurobiol. 6, 215-220 (1996
92. Horton, J. C., & Hoyt, W. F. Quadrantic visual field defects. A hallmark of lesions in extrastriate (V2/V3) cortex. Brain 114, 1703-1718 (1991
93. Mazzi, C., Mancini, F., & Savazzi, S. Can IPS reach visual awareness without V1?. Evidence from TMS in healthy subjects and hemianopic patients. Neuropsychologia 64C, 134-144 (2014
94. Zeki, S. A Vision of the Brain (Blackwell Scientific, 1993
95. Pollen, D. A. Fundamental requirements for primary visual perception. Cereb. Cortex 18, 1991-1998 (2008
96. Oizumi, M., Albantakis, L., & Tononi, G. From the phenomenology to the mechanisms of consciousness: integrated information theory 3.0. PLoS Comput. Biol. 10, e1003588 (2014
97. Meyer, K. Primary sensory cortices, top-down projections and conscious experience. Prog. Neurobiol. 94, 408-417 (2011
98. Wiegand, K., & Gutschalk, A. Correlates of perceptual awareness in human primary auditory cortex revealed by an informational masking experiment. Neuroimage 61, 62-69 (2012
99. Cauller, L. J., & Kulics, A. T. The neural basis of the behaviorally relevant N1 component of the somatosensory-evoked potential in SI cortex of awake monkeys: evidence that backward cortical projections signal conscious touch sensation. Exp. Brain Res. 84, 607-619 (1991
100. Goodale, M. A., & Milner, D. A. Sight Unseen: an Exploration of Conscious and Unconscious Vision (Oxford Univ. Press, 2004
101. Grill-Spector, K., & Weiner, K. S. The functional architecture of the ventral temporal cortex and its role in categorization. Nat. Rev. Neurosci. 15, 536-548 (2014
102. Karnath, H. O., Ruter, J., Mandler, A., & Himmelbach, M. The anatomy of object recognition - visual form agnosia caused by medial occipitotemporal stroke. J. Neurosci. 29, 5854-5862 (2009
103. Milner, A. D. Is visual processing in the dorsal stream accessible to consciousness?. Proc. Biol. Sci. 279, 2289-2298 (2012
104. Konen, C. S., & Kastner, S. Two hierarchically organized neural systems for object information in human visual cortex. Nat. Neurosci. 11, 224-231 (2008
105. Kravitz, D. J., Saleem, K. S., Baker, C. I., & Mishkin, M. A new neural framework for visuospatial processing. Nat. Rev. Neurosci. 12, 217-230 (2011
106. Bagattini, C., Mazzi, C., & Savazzi, S. Waves of awareness for occipital and parietal phosphenes perception. Neuropsychologia 70C, 114-125 (2015
107. Laureys, S., Lemaire, C., Maquet, P., Phillips, C., & Franck, G. Cerebral metabolism during vegetative state and after recovery to consciousness. J. Neurol. Neurosurg. Psychiatry 67, 121 (1999
108. Kaisti, K. K. et al. Effects of surgical levels of propofol and sevoflurane anesthesia on cerebral blood flow in healthy subjects studied with positron emission tomography. Anesthesiology 96, 1358-1370 (2002
109. Maquet, P. Functional neuroimaging of normal human sleep by positron emission tomography. J. Sleep Res. 9, 207-231 (2000
110. Kajimura, N. et al. Activity of midbrain reticular formation and neocortex during the progression of human non-rapid eye movement sleep. J. Neurosci. 19, 10065-10073 (1999
111. Vogt, B. A., & Laureys, S. Posterior cingulate, precuneal and retrosplenial cortices: cytology and components of the neural network correlates of consciousness. Prog. Brain Res. 150, 205-217 (2005
112. Bai, X. et al. Dynamic time course of typical childhood absence seizures: EEG, behavior, and functional magnetic resonance imaging. J. Neurosci. 30, 5884-5893 (2010
113. Safavi, S., Kapoor, V., Logothetis, N. K., & Panagiotaropoulos, T. I. Is the frontal lobe involved in conscious perception?. Front. Psychol. 5, 1063 (2014
114. Melloni, L., Schwiedrzik, C. M., Muller, N., Rodriguez, E., & Singer, W. Expectations change the signatures and timing of electrophysiological correlates of perceptual awareness. J. Neurosci. 31, 1386-1396 (2011
115. Sandberg, K. et al. Distinct MEG correlates of conscious experience, perceptual reversals and stabilization during binocular rivalry. Neuroimage 100, 161-175 (2014
116. Andersen, L. M., Pedersen, M. N., Sandberg, K., & Overgaard, M. Occipital MEG activity in the early time range
117. Noy, N. et al. Ignition's glow: ultra-fast spread of global cortical activity accompanying local "ignitions" in visual cortex during conscious visual perception. Conscious. Cogn. 35, 206-224 (2015
118. Nir, Y., & Tononi, G. Dreaming and the brain: from phenomenology to neurophysiology. Trends Cogn. Sci. 14, 88-100 (2010
119. Postle, B. R. The cognitive neuroscience of visual short term memory. Curr. Opin. Behav. Sci. 1, 40-46 (2015
120. Selimbeyoglu, A., & Parvizi, J. Electrical stimulation of the human brain: perceptual and behavioral phenomena reported in the old and new literature. Front. Hum. Neurosci. 4, 46 (2010
121. Rangarajan, V. et al. Electrical stimulation of the left and right human fusiform gyrus causes different effects in conscious face perception. J. Neurosci. 34, 12828-12836 (2014
122. Desmurget, M. et al. Movement intention after parietal cortex stimulation in humans. Science 324, 811-813 (2009
123. Brickner, R. M. Brain of patient A. after bilateral frontal lobectomy; status of frontal-lobe problem. AMA Arch. Neurol. Psychiatry 68, 293-313 (1952
124. Hebb, D. O., & Penfield, W. Human behavior after extensive bilateral removal from the frontal lobes. Arch. Neurol. Psychiatry 42, 421-438 (1940
125. Fulton, J. F. Functional Localization in Relation to Frontal Lobotomy (Oxford Univ. Press, 1949
126. Mettler, F. A. Selective Partial Ablation of the Frontal Cortex, a Correlative Study of its Effects on Human Psychotic Subjects (Hoebar, 1949
127. Markowitsch, H. J., & Kessler, J. Massive impairment in executive functions with partial preservation of other cognitive functions: the case of a young patient with severe degeneration of the prefrontal cortex. Exp. Brain Res. 133, 94-102 (2000
128. Mataró, M. et al. Long-Term effects of bilateral frontal brain lesion: 60 years after injury with an iron bar. Arch. Neurol. 58, 1139-1142 (2001
129. VanRullen, R., & Koch, C. Visual selective behavior can be triggered by a feed-forward process. J. Cogn. Neurosci. 15, 209-217 (2003
130. Schmidt, T., & Schmidt, F. Processing of natural images is feedforward: a simple behavioral test. Atten. Percept. Psychophys. 71, 594-606 (2009
131. Koivisto, M., Kastrati, G., & Revonsuo, A. Recurrent processing enhances visual awareness but is not necessary for fast categorization of natural scenes. J. Cogn. Neurosci. 26, 223-231 (2014
132. Lamme, V. A., & Roelfsema, P. R. The distinct modes of vision offered by feedforward and recurrent processing. Trends Neurosci. 23, 571-579 (2000
133. Tang, H. et al. Spatiotemporal dynamics underlying object completion in human ventral visual cortex. Neuron 83, 736-748 (2014
134. Super, H., Spekreijse, H., & Lamme, V. A. Two distinct modes of sensory processing observed in monkey primary visual cortex (V1). Nat. Neurosci. 4, 304-310 (2001
135. Auksztulewicz, R., Spitzer, B., & Blankenburg, F. Recurrent neural processing and somatosensory awareness. J. Neurosci. 32, 799-805 (2012
136. Sachidhanandam, S., Sreenivasan, V., Kyriakatos, A., Kremer, Y., & Petersen, C. C. Membrane potential correlates of sensory perception in mouse barrel cortex. Nat. Neurosci. 16, 1671-1677 (2013
137. Boly, M. et al. Preserved feedforward but impaired top-down processes in the vegetative state. Science 332, 858-862 (2011
138. Ku, S. W., Lee, U., Noh, G. J., Jun, I. G., & Mashour, G. A. Preferential inhibition of frontal-To parietal feedback connectivity is a neurophysiologic correlate of general anesthesia in surgical patients. PLoS ONE 6, e25155 (2011
139. Tononi, G., & Edelman, G. M. Consciousness and complexity. Science 282, 1846-1851 (1998
140. Lamme, V. A. F. Towards a true neural stance on consciousness. Trends Cogn. Sci. 10, 494-501 (2006
141. Dehaene, S., & Naccache, L. Towards a cognitive neuroscience of consciousness: basic evidence and a workspace framework. Cognition 79, 1-37 (2001
142. Dehaene, S., & Changeux, J. P. Experimental and theoretical approaches to conscious processing. Neuron 70, 200-227 (2011
143. Butti, C., Santos, M., Uppal, N., & Hof, P. R. Von Economo neurons: clinical and evolutionary perspectives. Cortex 49, 312-326 (2013
144. Livingstone, M. S., & Hubel, D. H. Effects of sleep and arousal on the processing of visual information in the cat. Nature 291, 554-561 (1981
145. Larkum, M. A cellular mechanism for cortical associations: an organizing principle for the cerebral cortex. Trends Neurosci. 36, 141-151 (2013
146. Harris, K. D., & Shepherd, G. M. The neocortical circuit: themes and variations. Nat. Neurosci. 18, 170-181 (2015
147. Douglas, R. J., & Martin, K. A. Neuronal circuits of the neocortex. Annu. Rev. Neurosci. 27, 419-451 (2004
148. Binzegger, T., Douglas, R. J., & Martin, K. A. Topology and dynamics of the canonical circuit of cat V1. Neural Netw. 22, 1071-1078 (2009
149. Markov, N. T. et al. Anatomy of hierarchy: feedforward and feedback pathways in macaque visual cortex. J. Comp. Neurol. 522, 225-259 (2014
150. Zhang, S. et al. Long-range and local circuits for top-down modulation of visual cortex processing. Science 345, 660-665 (2014
151. Maier, A., Adams, G. K., Aura, C., & Leopold, D. A. Distinct superficial and deep laminar domains of activity in the visual cortex during rest and stimulation. Front. Syst. Neurosci. 4, 31 (2010
152. Buffalo, E. A., Fries, P., Landman, R., Buschman, T. J., & Desimone, R. Laminar differences in gamma and alpha coherence in the ventral stream. Proc. Natl Acad. Sci. USA 108, 11262-11267 (2011
153. Funk, C.M., Honjoh, S., Rodriguez, A.V., Cirelli, C., & Tononi, G. Local slow waves in superficial layers of primary cortical areas during REM sleep. Curr. Biol. 26, 396-403 (2016
154. Sakata, S., & Harris, K. D. Laminar structure of spontaneous and sensory-evoked population activity in auditory cortex. Neuron 64, 404-418 (2009
155. Shew, W. L., & Plenz, D. The functional benefits of criticality in the cortex. Neuroscientist 19, 88-100 (2013
156. He, B. J., & Raichle, M. E. The fMRI signal, slow cortical potential and consciousness. Trends Cogn. Sci. 13, 302-309 (2009
157. Libet, B., Alberts, W. W., Wright, E. W. Jr, & Feinstein, B. Responses of human somatosensory cortex to stimuli below threshold for conscious sensation. Science 158, 1597-1600 (1967
158. Pins, D., & Ffytche, D. The neural correlates of conscious vision. Cereb. Cortex 13, 461-474 (2003
159. Fitzgerald, R. D. et al. Direct current auditory evoked potentials during wakefulness, anesthesia, and emergence from anesthesia. Anesth. Analg. 92, 154-160 (2001
160. Arezzo, J. C., Vaughan, H. G. Jr, & Legatt, A. D. Topography and intracranial sources of somatosensory evoked potentials in the monkey. II. Cortical components. Electroencephalogr. Clin. Neurophysiol. 51, 1-18 (1981
161. Cauller, L. J., & Kulics, A. T. A comparison of awake and sleeping cortical states by analysis of the somatosensory-evoked response of postcentral area 1 in rhesus monkey. Exp. Brain Res. 72, 584-592 (1988
162. Gray, C. M., Konig, P., Engel, A. K., & Singer, W. Oscillatory responses in cat visual cortex exhibit inter-columnar synchronization which reflects global stimulus properties. Nature 338, 334-337 (1989
163. Singer, W. Time as coding space?. Curr. Opin. Neurobiol. 9, 189-194 (1999
164. Roelfsema, P. R., Engel, A. K., Konig, P., & Singer, W. Visuomotor integration is associated with zero time-lag synchronization among cortical areas. Nature 385, 157-161 (1997
165. Munk, M. H., Roelfsema, P. R., Konig, P., Engel, A. K., & Singer, W. Role of reticular activation in the modulation of intracortical synchronization. Science 272, 271-274 (1996
166. Herculano-Houzel, S., Munk, M. H., Neuenschwander, S., & Singer, W. Precisely synchronized oscillatory firing patterns require electroencephalographic activation. J. Neurosci. 19, 3992-4010 (1999
167. Fries, P., Roelfsema, P. R., Engel, A. K., Konig, P., & Singer, W. Synchronization of oscillatory responses in visual cortex correlates with perception in interocular rivalry. Proc. Natl Acad. Sci. USA 94, 12699-12704 (1997
168. Rodriguez, E. et al. Perception's shadow: long-distance synchronization of human brain activity. Nature 397, 430-433 (1999
169. Melloni, L. et al. Synchronization of neural activity across cortical areas correlates with conscious perception. J. Neurosci. 27, 2858-2865 (2007
170. Wyart, V., & Tallon-Baudry, C. Neural dissociation between visual awareness and spatial attention. J. Neurosci. 28, 2667-2679 (2008
171. Imas, O. A., Ropella, K. M., Ward, B. D., Wood, J. D., & Hudetz, A. G. Volatile anesthetics disrupt frontal-posterior recurrent information transfer at gamma frequencies in rat. Neurosci. Lett. 387, 145-150 (2005
172. Murphy, M. J. et al. Propofol anesthesia and sleep: a high-density EEG study. Sleep 34, 283 91A (2011
173. Pockett, S., & Holmes, M. D. Intracranial EEG power spectra and phase synchrony during consciousness and unconsciousness. Conscious. Cogn. 18, 1049-1055 (2009
174. Luo, Q. et al. Visual awareness, emotion, and gamma band synchronization. Cereb. Cortex 19, 1896-1904 (2009
175. Hermes, D., Miller, K. J., Wandell, B. A., & Winawer, J. Stimulus dependence of gamma oscillations in human visual cortex. Cereb. Cortex 25, 2951-2959 (2015
176. Ray, S., & Maunsell, J. H. Network rhythms influence the relationship between spike-Triggered local field potential and functional connectivity. J. Neurosci. 31, 12674-12682 (2011
177. Sutton, S., Braren, M., Zubin, J., & John, E. R. Evoked-potential correlates of stimulus uncertainty. Science 150, 1187-1188 (1965
178. Sergent, C., Baillet, S., & Dehaene, S. Timing of the brain events underlying access to consciousness during the attentional blink. Nat. Neurosci. 8, 1391-1400 (2005
179. Pitts, M. A., Martínez, A., & Hillyard, S. A. Visual processing of contour patterns under conditions of inattentional blindness. J. Cogn. Neurosci. 24, 287-303 (2012
180. Silverstein, B. H., Snodgrass, M., Shevrin, H., & Kushwaha, R. P3b, consciousness, and complex unconscious processing. Cortex 73, 216-227 (2015
181. Sitt, J. D. et al. Large scale screening of neural signatures of consciousness in patients in a vegetative or minimally conscious state. Brain 137, 2258-2270 (2014
182. Kotchoubey, B. Event-related potential measures of consciousness: two equations with three unknowns. Prog. Brain Res. 150, 427-444 (2005
183. Fischer, C., Luaute, J., & Morlet, D. Event-related potentials (MMN and novelty P3) in permanent vegetative or minimally conscious states. Clin. Neurophysiol. 121, 1032-1042 (2010
184. Holler, Y. et al. Preserved oscillatory response but lack of mismatch negativity in patients with disorders of consciousness. Clin. Neurophysiol. 122, 1744-1754 (2011
185. Faugeras, F. et al. Probing consciousness with event-related potentials in the vegetative state. Neurology 77, 264-268 (2011
186. King, J. R. et al. Single-Trial decoding of auditory novelty responses facilitates the detection of residual consciousness. Neuroimage 83, 726-738 (2013
187. Tzovara, A., Simonin, A., Oddo, M., Rossetti, A. O., & De Lucia, M. Neural detection of complex sound sequences in the absence of consciousness. Brain 138, 1160-1166 (2015
188. Railo, H., Koivisto, M., & Revonsuo, A. Tracking the processes behind conscious perception: a review of event-related potential correlates of visual consciousness. Conscious. Cogn. 20, 972-983 (2011
189. Steriade, M. Corticothalamic resonance, states of vigilance and mentation. Neuroscience 101, 243-276 (2000
190. Steriade, M., Timofeev, I., & Grenier, F. Natural waking and sleep states: a view from inside neocortical neurons. J. Neurophysiol. 85, 1969-1985 (2001
191. McCormick, D. A., Wang, Z., & Huguenard, J. Neurotransmitter control of neocortical neuronal activity and excitability. Cereb. Cortex 3, 387-398 (1993
192. Schiff, N. D. Central thalamic deep-brain stimulation in the severely injured brain: rationale and proposed mechanisms of action. Ann. NY Acad. Sci. 1157, 101-116 (2009
193. Timofeev, I., Grenier, F., Bazhenov, M., Sejnowski, T. J., & Steriade, M. Origin of slow cortical oscillations in deafferented cortical slabs. Cereb. Cortex 10, 1185-1199 (2000
194. Fernandez-Espejo, D. et al. Diffusion weighted imaging distinguishes the vegetative state from the minimally conscious state. Neuroimage 54, 103-112 (2011
195. Kertai, M. D., Whitlock, E. L., & Avidan, M. S. Brain monitoring with electroencephalography and the electroencephalogram-derived bispectral index during cardiac surgery. Anesth. Analg. 114, 533-546 (2012
196. Purdon, P. L. et al. Electroencephalogram signatures of loss and recovery of consciousness from propofol. Proc. Natl Acad. Sci. USA 110, E1142-E1151 (2013
197. Schiff, N. D., Nauvel, T., & Victor, J. D. Large-scale brain dynamics in disorders of consciousness. Curr. Opin. Neurobiol. 25, 7-14 (2014
198. Westmoreland, B. F., Klass, D. W., Sharbrough, F. W., & Reagan, T. J. Alpha-coma. Electroencephalographic, clinical, pathologic, and etiologic correlations. Arch. Neurol. 32, 713-718 (1975
199. Gökyig?it, A., & Calişkan, A. Diffuse spike-wave status of 9 year duration without behavioral change or intellectual decline. Epilepsia 36, 210-213 (1995
200. Vuilleumier, P., Assal, F., Blanke, O., & Jallon, P. Distinct behavioral and EEG topographic correlates of loss of consciousness in absences. Epilepsia 41, 687-693 (2000
201. Nobili, L. et al. Local aspects of sleep: observations from intracerebral recordings in humans. Prog. Brain Res. 199, 219-232 (2012
202. Forgacs, P. B. et al. Preservation of electroencephalographic organization in patients with impaired consciousness and imaging-based evidence of command-following. Ann. Neurol. 76, 869-879 (2014
203. Synek, V. M. Prognostically important EEG coma patterns in diffuse anoxic and traumatic encephalopathies in adults. J. Clin. Neurophysiol. 5, 161-174 (1988
204. Hudetz, A. G., Liu, X., & Pillay, S. Dynamic repertoire of intrinsic brain states is reduced in propofol-induced unconsciousness. Brain Connect. 5, 10-22 (2015
205. Barttfeld, P. et al. Signature of consciousness in the dynamics of resting-state brain activity. Proc. Natl Acad. Sci. USA 112, 887-892 (2015
206. Solovey, G. et al. Loss of consciousness is associated with stabilization of cortical activity. J. Neurosci. 35, 10866-10877 (2015
207. Sigl, J. C., & Chamoun, N. G. An introduction to bispectral analysis for the electroencephalogram. J. Clin. Monit. 10, 392-404 (1994
208. Sara, M. et al. Functional isolation within the cerebral cortex in the vegetative state: a nonlinear method to predict clinical outcomes. Neurorehabil. Neural Repair 25, 35-42 (2011
209. Gosseries, O. et al. Automated EEG entropy measurements in coma, vegetative state/unresponsive wakefulness syndrome and minimally conscious state. Funct. Neurol. 26, 25-30 (2011
210. Tagliazucchi, E., & Laufs, H. Decoding wakefulness levels from typical fMRI resting-state data reveals reliable drifts between wakefulness and sleep. Neuron 82, 695-708 (2014
211. Achard, S. et al. Hubs of brain functional networks are radically reorganized in comatose patients. Proc. Natl Acad. Sci. USA 109, 20608-20613 (2012
212. Monti, M. M. et al. Dynamic change of global and local information processing in propofol-induced loss and recovery of consciousness. PLoS Comput. Biol. 9, e1003271 (2013
213. King, J. R. et al. Information sharing in the brain indexes consciousness in noncommunicative patients. Curr. Biol. 23, 1914-1919 (2013
214. Marinazzo, D. et al. Directed information transfer in scalp electroencephalographic recordings: insights on disorders of consciousness. Clin. EEG Neurosci. 45, 33-39 (2014
215. Chennu, S. et al. Spectral signatures of reorganised brain networks in disorders of consciousness. PLoS Comput. Biol. 10, e1003887 (2014
216. Supp, G. G., Siegel, M., Hipp, J. F., & Engel, A. K. Cortical hypersynchrony predicts breakdown of sensory processing during loss of consciousness. Curr. Biol. 21, 1988-1993 (2011
217. Arthuis, M. et al. Impaired consciousness during temporal lobe seizures is related to increased long-distance cortical-subcortical synchronization. Brain 132, 2091-2101 (2009
218. Kaskinoro, K. et al. Wide inter-individual variability of bispectral index and spectral entropy at loss of consciousness during increasing concentrations of dexmedetomidine, propofol, and sevoflurane. Br. J. Anaesth. 107, 573-580 (2011
219. Casali, A. G. et al. A theoretically based index of consciousness independent of sensory processing and behavior. Sci. Transl. Med. 5, 198ra105 (2013
220. Sarasso, S. et al. Consciousness and complexity during unresponsiveness induced by propofol, xenon, and ketamine. Curr. Biol. 25, 3099-3105 (2015
221. Miller, S. (ed.) The Constitution of Phenomenal Consciousness: Toward a Science and Theory (John Benjamins Publishing, 2015
222. Revonsuo, A. in Neural Correlates of Consciousness. (ed. Metzinger, T.) 57-76 (MIT Press, 2000
223. Coltheart, V. Fleeting Memories: Cognition of Brief Visual Stimuli. (MIT Press, 1999
224. Tononi, G., Boly, M., Massimini, M., & Koch, C. Integrated information theory: from consciousness to its physical substrate. Nat. Rev Neurosci. (in the press)
225. Monti, M. M. et al. Willful modulation of brain activity in disorders of consciousness. N. Engl. J. Med. 362, 579-589 (2010
226. Schiff, N. et al. Residual cerebral activity and behavioural fragments can remain in the persistently vegetative brain. Brain 125, 1210-1234 (2002
227. Zadra, A., Desautels, A., Petit, D., & Montplaisir, J. Somnambulism: clinical aspects and pathophysiological hypotheses. Lancet Neurol. 12, 285-294 (2013
228. Bassetti, C., Vella, S., Donati, F., Wielepp, P., & Weder, B. SPECT during sleepwalking. Lancet 356, 484-485 (2000
229. Terzaghi, M. et al. Dissociated local arousal states underlying essential clinical features of non-rapid eye movement arousal parasomnia: an intracerebral stereo-electroencephalographic study. J. Sleep Res. 21, 502-506 (2012
230. Blumenfeld, H. Impaired consciousness in epilepsy. Lancet Neurol. 11, 814-826 (2012
231. Langston, J W., & Palfreman, J. The Case of the Frozen Addicts (Pantheon, 1995
232. Northoff, G. et al. Right lower prefronto-parietal cortical dysfunction in akinetic catatonia: a combined study of neuropsychology and regional cerebral blood flow. Psychol. Med. 30, 583-596 (2000
233. Lagercrantz, H., & Changeux, J. P. The emergence of human consciousness: from fetal to neonatal life. Pediatr. Res. 65, 255-260 (2009
234. Kouider, S. et al. A neural marker of perceptual consciousness in infants. Science 340, 376-380 (2013
235. Dawkins, M. S. Through Our Eyes Only?. (Oxford Univ. Press on Demand, 1998
236. Griffin, D. R. Animal Minds (University of Chicago Press, 2001
237. Edelman, D., & Seth, A. K. Animal consciousness: a synthetic approach. Trends Neurosci. 32, 476-484 (2009
238. Koch, C., & Laurent, G. Complexity and the nervous system. Science 284, 96-98 (1999
239. Berlin, H. A. The neural basis of the dynamic unconscious. Neuropsychoanalysis 13, 1-68 (2011
240. Hassin, R. R. Yes it can: on the functional abilities of the human unconscious. Persp. Psychol. Sci. 8, 195-207 (2013
241. Hassin, R. R., Uleman, J. S., & Bargh, J. A. The New Unconscious (Oxford Univ. Press, 2005
242. Sklar, A. Y. et al. Reading and doing arithmetic nonconsciously. Proc. Natl Acad. Sci. USA 109, 19614-19619 (2012
243. Kouider, S., & Dehaene, S. Levels of processing during non-conscious perception: a critical review of visual masking. Phil. Trans. R. Soc. B 362, 857-875 (2007
244. Mudrik, L., Breska, A., Lamy, D., & Deouell, L. Y. Integration without awareness: expanding the limits of unconscious processing. Psychol. Sci. 22, 764-770 (2011
245. Giurfa, M., Zhang, S., Jenett, A., Menzel, R., & Srinivasan, M. V. The concepts of 'sameness' and 'difference' in an insect. Nature 410, 930-933 (2001
246. Tononi, G., & Koch, C. Consciousness: here, there, and everywhere?. Phil. Trans. R. Soc. B http://dx.doi.org/ 10.1098/rstb.2014.0167 (2015
247. Steriade, M., Amzica, F., & Contreras, D. Synchronization of fast (30-40 Hz) spontaneous cortical rhythms during brain activation. J. Neurosci. 16, 392-417 (1996
248. Steriade, M. Arousal: revisiting the reticular activating system. Science 272, 225-226 (1996