title: Consciousness: here, there and everywhere?
abstract: The science of consciousness has made great strides by focusing on the behavioural and neuronal correlates of experience. However, while such correlates are important for progress to occur, they are not enough if we are to understand even basic facts, for example, why the cerebral cortex gives rise to consciousness but the cerebellum does not, though it has even more neurons and appears to be just as complicated. Moreover, correlates are of little help in many instances where we would like to know if consciousness is present: patients with a few remaining islands of functioning cortex, preterm infants, non-mammalian species and machines that are rapidly outperforming people at driving, recognizing faces and objects, and answering difficult questions. To address these issues, we need not only more data but also a theory of consciousness-one that says what experience is and what type of physical systems can have it. Integrated information theory (IIT) does so by starting from experience itself via five phenomenological axioms: intrinsic existence, composition, information, integration and exclusion. From these it derives five postulates about the properties required of physical mechanisms to support consciousness. The theory provides a principled account of both the quantity and the quality of an individual experience (a quale), and a calculus to evaluate whether or not a particular physical system is conscious and of what. Moreover, IIT can explain a range of clinical and laboratory findings, makes a number of testable predictions and extrapolates to a number of problematic conditions. The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms and can occur in some very simple systems. Conversely, it predicts that feed-forward networks, even complex ones, are not conscious, nor are aggregates such as groups of individuals or heaps of sand. Also, in sharp contrast to widespread functionalist beliefs, IIT implies that digital computers, even if their behaviour were to be functionally equivalent to ours, and even if they were to run faithful simulations of the human brain, would experience next to nothing.
authors.affiliation: Department of Psychiatry, University of Wisconsin, Madison WI, USA.
authors.forename: Giulio
authors.initials: G
authors.lastname: Tononi
authors.affiliation: Allen Institute for Brain Science, Seattle, WA, USA christofk@alleninstitute.org.
authors.forename: Christof
authors.initials: C
authors.lastname: Koch
mesh_terms: D001185:Artificial Intelligence; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D001931:Brain Mapping; D003243:Consciousness / Q000502:physiology*; D006801:Humans; D009415:Nerve Net
keywords: awareness; causation; cerebral cortex; existence; mind body problem; neuronal correlates of consciousness
references.citation: Science. 1999 Apr 2;284(5411):96-8
references.pmid: 10102826
references.citation: Neuropsychiatry Neuropsychol Behav Neurol. 2000 Jan;13(1):67-76
references.pmid: 10645739
references.citation: Trends Cogn Sci. 2001 Jan 1;5(1):16-25
references.pmid: 11164732
references.citation: Brain. 2001 Jul;124(Pt 7):1263-89
references.pmid: 11408323
references.citation: Nature. 2001 Jun 21;411(6840):893
references.pmid: 11418835
references.citation: Arch Neurol. 2001 Jul;58(7):1139-42
references.pmid: 11448304
references.citation: Sleep. 2001 Nov 1;24(7):791-803
references.pmid: 11683482
references.citation: Brain. 2002 Jun;125(Pt 6):1210-34
references.pmid: 12023311
references.citation: Psychiatry Clin Neurosci. 2002 Jun;56(3):257-8
references.pmid: 12047584
references.citation: Nat Neurosci. 2003 Feb;6(2):119-26
references.pmid: 12555104
references.citation: Ann N Y Acad Sci. 2002 Dec;978:135-55
references.pmid: 12582048
references.citation: Trends Cogn Sci. 2003 May;7(5):207-213
references.pmid: 12757822
references.citation: Brain. 2003 Jul;126(Pt 7):1524-36
references.pmid: 12805123
references.citation: Trends Neurosci. 2003 Dec;26(12):671-5
references.pmid: 14624851
references.citation: BMC Neurosci. 2004 Nov 02;5:42
references.pmid: 15522121
references.citation: Conscious Cogn. 2005 Mar;14(1):119-39
references.pmid: 15766894
references.citation: Anesthesiology. 2005 May;102(5):937-47
references.pmid: 15851880
references.citation: Nat Rev Neurosci. 2005 Aug;6(8):653-9
references.pmid: 16062172
references.citation: Philos Trans R Soc Lond B Biol Sci. 2005 Jun 29;360(1458):1271-9
references.pmid: 16147522
references.citation: Science. 2005 Sep 30;309(5744):2228-32
references.pmid: 16195466
references.citation: Nat Rev Neurosci. 2006 Feb;7(2):153-60
references.pmid: 16429124
references.citation: Neuron. 2006 Apr 20;50(2):329-39
references.pmid: 16630842
references.citation: Science. 2006 Sep 8;313(5792):1402
references.pmid: 16959998
references.citation: Trends Cogn Sci. 2006 Nov;10(11):494-501
references.pmid: 16997611
references.citation: Nat Neurosci. 2007 Feb;10(2):257-61
references.pmid: 17237774
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 May 29;362(1481):857-75
references.pmid: 17403642
references.citation: Behav Brain Sci. 2007 Dec;30(5-6):481-99; discussion 499-548
references.pmid: 18366828
references.citation: Ann N Y Acad Sci. 2008 Mar;1124:239-61
references.pmid: 18400934
references.citation: Electroencephalogr Clin Neurophysiol. 1949 Nov;1(4):455-73
references.pmid: 18421835
references.citation: PLoS Comput Biol. 2008 Jun 13;4(6):e1000091
references.pmid: 18551165
references.citation: Nature. 2008 Sep 11;455(7210):227-31
references.pmid: 18690210
references.citation: Pediatr Res. 2009 Mar;65(3):255-60
references.pmid: 19092726
references.citation: Biol Bull. 2008 Dec;215(3):216-42
references.pmid: 19098144
references.citation: J Neurosci. 1991 Nov;11(11):3656-66
references.pmid: 1941101
references.citation: PLoS Comput Biol. 2009 Aug;5(8):e1000462
references.pmid: 19680424
references.citation: Trends Neurosci. 2009 Sep;32(9):476-84
references.pmid: 19716185
references.citation: Front Hum Neurosci. 2009 Nov 09;3:31
references.pmid: 19915731
references.citation: Neuropsychologia. 2010 Mar;48(4):970-7
references.pmid: 19944708
references.citation: Conscious Cogn. 2010 Dec;19(4):1069-78
references.pmid: 20133167
references.citation: Brain. 2010 Mar;133(Pt 3):652-4
references.pmid: 20305277
references.citation: Cold Spring Harb Symp Quant Biol. 1990;55:953-62
references.pmid: 2132872
references.citation: Sleep. 2011 Mar 01;34(3):283-91A
references.pmid: 21358845
references.citation: Neuron. 2011 Apr 28;70(2):200-27
references.pmid: 21521609
references.citation: Psychol Sci. 2011 Jun;22(6):764-70
references.pmid: 21555524
references.citation: Sci Am. 2011 Jun;304(6):44-7
references.pmid: 21608402
references.citation: Trends Cogn Sci. 2011 Aug;15(8):358-64
references.pmid: 21807333
references.citation: J Cogn Neurosci. 2012 Feb;24(2):287-303
references.pmid: 21812561
references.citation: PLoS Comput Biol. 2011 Oct;7(10):e1002236
references.pmid: 22028639
references.citation: Trends Cogn Sci. 2012 Feb;16(2):103-5
references.pmid: 22154091
references.citation: Proc Natl Acad Sci U S A. 2012 Jun 26;109 Suppl 1:10661-8
references.pmid: 22723358
references.citation: Trends Cogn Sci. 2012 Aug;16(8):411-7
references.pmid: 22795561
references.citation: Nature. 2012 Sep 20;489(7416):391-399
references.pmid: 22996553
references.citation: J Neurosci. 2012 Oct 24;32(43):14909-14
references.pmid: 23100413
references.citation: Proc Natl Acad Sci U S A. 2012 Nov 27;109(48):19614-9
references.pmid: 23150541
references.citation: Arch Ital Biol. 2012 Jun-Sep;150(2-3):56-90
references.pmid: 23165867
references.citation: Science. 2013 Apr 19;340(6130):376-80
references.pmid: 23599498
references.citation: PLoS Comput Biol. 2013;9(7):e1003111
references.pmid: 23874168
references.citation: J Comp Psychol. 2014 May;128(2):143-9
references.pmid: 23875919
references.citation: Sci Transl Med. 2013 Aug 14;5(198):198ra105
references.pmid: 23946194
references.citation: J Comp Psychol. 2014 May;128(2):115-31
references.pmid: 23957740
references.citation: Nature. 2013 Sep 19;501(7467):373-9
references.pmid: 23995685
references.citation: Curr Biol. 2013 Oct 7;23(19):1914-9
references.pmid: 24076243
references.citation: Front Psychol. 2013 Oct 31;4:625
references.pmid: 24198791
references.citation: Proc Natl Acad Sci U S A. 2013 Dec 3;110(49):19790-5
references.pmid: 24248356
references.citation: J Vis. 2013 Nov 22;13(13):24
references.pmid: 24273226
references.citation: Proc Natl Acad Sci U S A. 2014 Feb 11;111(6):2081-6
references.pmid: 24469794
references.citation: J Neurosci. 2014 Jan 29;34(5):1738-47
references.pmid: 24478356
references.citation: Philos Trans R Soc Lond B Biol Sci. 2014 Mar 17;369(1641):20130214
references.pmid: 24639585
references.citation: PLoS Comput Biol. 2014 May 08;10(5):e1003588
references.pmid: 24811198
references.citation: Trends Cogn Sci. 2014 Sep;18(9):488-96
references.pmid: 24933626
references.citation: Epilepsy Behav. 2014 Aug;37:32-5
references.pmid: 24967698
references.citation: PLoS Comput Biol. 2014 Dec 18;10(12):e1003966
references.pmid: 25521484
references.citation: Perspect Psychol Sci. 2013 Mar;8(2):195-207
references.pmid: 26172502
references.citation: Acta Neuropsychiatr. 2007 Jun;19(3):159-76
references.pmid: 26952854
references.citation: Bull Clin Neurosci. 1986;51:3-29
references.pmid: 3331951
references.citation: Percept Psychophys. 1984 Oct;36(4):387-95
references.pmid: 6522236
references.citation: Nature. 1995 Jan 19;373(6511):247-9
references.pmid: 7816139
references.citation: Proc Biol Sci. 1997 Oct 22;264(1387):1407-14
references.pmid: 9364780
references.citation: Proc Biol Sci. 1997 Oct 22;264(1387):1415-9
references.pmid: 9364781
references.citation: Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3198-203
references.pmid: 9501240
references.citation: Cereb Cortex. 1998 Mar;8(2):97-107
references.pmid: 9542889
references.citation: Proc Natl Acad Sci U S A. 1998 Dec 8;95(25):15032-6
references.pmid: 9844010
references.citation: Philos Trans R Soc Lond B Biol Sci. 1998 Nov 29;353(1377):1801-18
references.pmid: 9854253