Neural correlates of consciousness: progress and problems

Koch, Massimini, Boly, Tononi · Nature Reviews Neuroscience · 2016 · neuroscience · 10.1038/nrn.2016.22 · record koch2016-neural-correlates-of-consciousness
tag layer · index · concepts · authors · עברית

Where this record's text came from. faceted 2026-08 by reading the locally held text (pdftext); every evidence string verified as an exact substring of that text before merging. Claim type is 'existence' because the headline contribution is a localisation claim (the NCC are in the posterior hot zone, not fronto-parietal cortex); the paper is simultaneously a sustained critique of two candidate markers, which is captured in claim relations instead. Replication status is 'contested' because the paper itself records live disagreement on its central territory — no-report and lesion evidence against the fronto-parietal view, but it also notes 'However, other findings contradict this interpretation' regarding fronto-parietal candidacy, and describes the thalamus's role as controversial. Note on claim relations: this journal cites by superscript number, so no prior work is named in running text; the two relations recorded are ones the paper explicitly frames as a proposal it then rejects, and the targets are described rather than named. Relations to the earlier NRN review ('since the subject was last reviewed in this journal3') were left out for the same reason — the target is identified only by a citation number. 2026-08-14 schema-0.3 pass: every quote verified as an exact substring of the staged text and anchored at merge time; concept terms verified present; every edge endpoint an existing node.

1 quote on this page breaks a word across a line. The PDF this text was extracted from hyphenated a word at the end of a printed line — adversar- ial, repre- sentations — and the extractor kept the hyphen and the space. The quotes keep them because a quote is reproduced exactly or it proves nothing: the break is the typesetter’s, not the author’s. A search of this page will not find the affected words.

This record’s own method is review, and the tags below follow from that. A review’s findings, quantities and statistics are things stated IN this paper, and some of them report results obtained elsewhere. No tag on this page names a different author. Measured across every review in this corpus, 81% of a review’s tags carry no citation at all — most of them are the review speaking. The corpus does not adjudicate the rest: read an unmarked tag as a claim this paper makes, not necessarily one it made first.

How to read this page. The article itself is not reproduced here — this paper is not cleared for redistribution, so what follows is the tag layer alone. The evidence sentences are withheld with the article. The table at the foot lists every tag the record carries; each row names the facet it belongs to, and the whose words column says whether the tag records the paper's own wording or the tagger's sentence about the paper. Every tag links to each other paper in the corpus carrying it. The machine-readable edition of the same thing is the TEI file beside this one, where the tags live in standOff, and the article is at its publisher via the link below. When we have changed our mind. Some entries in the table begin with a word in capitals and the reason for it. EVIDENCE CORRECTED — the finding still stands, but we had quoted the wrong sentence from the paper, and the quotation has been replaced with the right one. RETRACTED — the entry itself was wrong; it stays on the page, marked, with the reason, rather than being deleted. WITHDRAWN AND REPLACED — the entry was wrong, and a corrected version of it appears in the entries below. Each mark carries its own reason, in brackets, because the reasons differ from one entry to the next. An entry we have WITHDRAWN is removed from this page and kept in the record, with its reason. A line reading Audit and a date is a later re-reading of the entry against its whole sentence: DOUBTFUL means it was kept, and the reason says what is loose about it. Quotation marks inside the tagger's sentence. Where a tag is the tagger's own sentence, a phrase in quotation marks inside it is borrowed from the paper — the tagger's wording around it is not. The paper's own sentence is the evidence quote for that row; on this page it is withheld with the article, and the article is at its publisher. Nothing inside quotation marks anywhere on this page is ours: if it is quoted, it is the paper's. Whose words a concept carries. A concept entry records a term the paper itself uses, so the term, the sense given for it, and its evidence are the paper's own words, quoted where the paper fixes them. This is the opposite of a sense entry in the tag table, which is the tagger's sentence about how the paper uses a term. Where a concept entry could not be grounded in the paper's words, the entry says so on its own row.

Other fields define these differently the same word, defined another way in another discipline
consciousness 10 fields

Tags on this paper

Every tag the record carries, each linking to every other paper in the corpus that carries it. A tag appears here whether or not its words occur in the article — the spans below are only the ones a sentence in this paper licenses. Of the 6 concept tags on this paper, all 6 are grounded in a quoted sentence.

full NCC contentspecific NCC gamma activity P3b wave behavioural responses consciousness Diffusely projecting brainstem, hypothalamic and basal forebrain populations depolarize thalamic and cortical neurons, and this depolarization enables consciousness indirectly by making effective interactions between cortical areas possible. Fronto-parietal activity co-varies with reported perception because report-based tasks recruit attention, expectation, self-monitoring, planning and reporting, which precede or follow the experience rather than constituting it. Brainstem reticular formation, paramedian thalamus and postero-medial cortex act as activating influences and cortical hubs, thereby enabling the interactions among the cortical areas that supply conscious content. neural correlates of consciousness (NCC) content-specific NCC background conditions for consciousness posterior cortical hot zone no-report paradigm perturbational complexity index (PCI) neuronal avalanches P3b review

Legend

relation to other work	`claim_relations`	how this paper stands to another: agrees, contradicts, extends, qualifies
claim type	`claim_type`	the shape of the claim: existence, mechanism, method, critique, prediction, null
concept edge	`concept_edges`	an asserted relation between two concepts, with the sentence asserting it
concept	`concepts`	an idea the paper works with, quoted where the paper uses it
content tag	`content_tags`	a finding, definition, quantity, statistic or variable named in the paper
limitation	`limitations`	what the paper says its evidence cannot support
mechanism	`mechanisms`	how the reported effect is said to come about
method	`method`	how the paper produced its evidence
phenomenon	`phenomenon`	the effect or regularity under study
sense	`senses`	a distinct use of a term, quoted where the paper fixes it

The paper

The full text is not reproduced here. This article is not cleared for redistribution, so the page carries the tag layer only. Its evidence sentences are withheld; the grounding status remains with each tag, and the article itself is at https://doi.org/10.1038/nrn.2016.22. The reading view exists for the papers whose licence permits it.

Every tag on this page

claim_relations 2 · claim_type 1 · concept_edges 3 · concepts 6 · content_tags 26 · limitations 7 · mechanisms 3 · method 1 · phenomenon 1 · senses 3

Relations on this page carry a quotation for the claim. Where a relation was separately evidenced — and so tested against the vocabulary for its type — the row says so; none of 3 relations here carry that mark. The rest are the tagger’s reading of the sentence quoted beside them.

This record holds no controls. A layer is empty when the tagger recorded nothing in it — which is not the same as the paper having nothing to record.

facet	tag	field	conf.	whose words
claim_type	existence Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_type`		the paper's words
phenomenon	neural correlates of consciousness Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`phenomenon`		the paper's words
method	review Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: review	`method`		the paper's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Diffusely projecting brainstem, hypothalamic and basal forebrain populations depolarize thalamic and cortical neurons, and this depolarization enables consciousness indirectly by making effective interactions between cortical areas possible.	`mechanisms[0]`		the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Fronto-parietal activity co-varies with reported perception because report-based tasks recruit attention, expectation, self-monitoring, planning and reporting, which precede or follow the experience rather than constituting it.	`mechanisms[1]`		the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Brainstem reticular formation, paramedian thalamus and postero-medial cortex act as activating influences and cortical hubs, thereby enabling the interactions among the cortical areas that supply conscious content.	`mechanisms[2]`		the tagger's words
limitations	The review restricts itself to visual and auditory studies and does not cover other modalities or metacognition. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the modality coverage of the review: THIS REVIEW FOCUSES ON VISUAL AND AUDITORY STUDIES; FOR ACCOUNTS OF THE NCC FOR METACOGNITION, BODY, TACTILE AND OLFACTORY EXPERIENCES, SEE REFS	`limitations[0]`		the tagger's words
limitations	The authors state that the empirical NCC research programme has inherent limits. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the empirical programme as a route to the question: WE OUTLINE THE INHERENT LIMITS OF SUCH AN EMPIRICAL RESEARCH PROGRAMME	`limitations[1]`		the tagger's words
limitations	NCC evidence cannot settle whether consciousness is present in brain-damaged patients, infants, animals or machines. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: every clinical, developmental, comparative and machine application: THE NCC BY THEMSELVES CAN PROVIDE LITTLE INFORMATION ABOUT CONSCIOUSNESS IN PATIENTS WITH SEVERE BRAIN DAMAGE, INFANTS, FETUSES, NON-HUMAN SPECIES OR INTELLIGENT MACHINES	`limitations[2]`		the tagger's words
limitations	The conclusion that V1 is not part of the content-specific NCC may not generalise to untested visual attributes. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the conclusion that V1 is outside the content-specific NCC: IT IS NOT KNOWN WHETHER THIS CONCLUSION APPLIES TO OTHER VISUAL ATTRIBUTES, SUCH AS PRECISE SPATIAL TOPOGRAPHY, LUMINOSITY AND DETAILED CONTOURS	`limitations[3]`		the tagger's words
limitations	The field's central definition is stated by its own authors to admit two interpretations. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: any use of the NCC as a single construct: the authors define it as the minimum neuronal mechanisms jointly sufficient for any one specific conscious percept, and state that there are two possible interpretations of that definition	`limitations[4]`	1.0	the tagger's words
limitations	Two popular candidate markers are reported to have no predictive power. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: any use of gamma activity or the P3b wave as a marker of consciousness: the authors state these two popular candidates have not shown any predictive power	`limitations[5]`	1.0	the tagger's words
limitations	Consciousness is stated to be possible without reliable behavioural responses, with the misclassification named. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: any inference from absent behaviour to absent consciousness: the authors state consciousness can be present even without reliable behavioural responses, and that minimally conscious patients can be misclassified as vegetative	`limitations[6]`	1.0	the tagger's words
concepts	full NCC Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: full NCC	`concepts[0]`		the paper's words
concepts	contentspecific NCC Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: contentspecific NCC	`concepts[1]`		the paper's words
concepts	gamma activity Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: gamma activity	`concepts[2]`		the paper's words
concepts	P3b wave Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: P3b wave	`concepts[3]`		the paper's words
concepts	behavioural responses Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: behavioural responses	`concepts[4]`		the paper's words
concepts	consciousness Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: consciousness	`concepts[5]`		the paper's words
senses	the NCC - ONE DEFINITION, TWO READINGS, FLAGGED BY ITS AUTHORS: the minimum neuronal mechanisms jointly sufficient for any one specific conscious percept, with the review stating there are two possible interpretations depending on whether the specific content or the state is meant; the definition does not determine its own referent Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[0]`	1.0	the tagger's words
senses	the full NCC - A UNION OVER A SET STILL BEING ENUMERATED: it is constituted by the union of all content-specific NCC, so the whole is complete exactly when the enumeration is, and the enumeration is the research programme itself Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[1]`	1.0	the tagger's words
senses	gamma activity and the P3b wave - CANDIDATE MARKERS WITHDRAWN: both were popular and neither has shown predictive power, so two named quantities that circulated as indices of consciousness are reported as failing the role Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[2]`	1.0	the tagger's words
claim_relations	contradicts → the proposal that the P3b/global ignition of fronto-parietal cortex is a signature of consciousness (REF. 142) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_relations[0]`		the tagger's words
claim_relations	contradicts → earlier proposals that gamma activity or synchrony, and the P3b event-related potential, are signatures of consciousness Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_relations[1]`		the tagger's words
concept_edges	contentspecific NCC —part-of→ full NCC Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. strength of the relation: 1 also in: contentspecific NCC · full NCC	`concept_edges[0]`		the tagger's words
concept_edges	gamma activity —causes→ consciousness Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. direction on the measure: no-change · strength of the relation: 1 also in: gamma activity · consciousness	`concept_edges[1]`		the tagger's words
concept_edges	P3b wave —causes→ consciousness Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. direction on the measure: no-change · strength of the relation: 1 also in: P3b wave · consciousness	`concept_edges[2]`		the tagger's words
content_tags	Both the full and the content-specific NCC sit in a restricted temporo-parieto-occipital posterior hot zone rather than in the wide fronto-parietal network that earlier work emphasised. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[0]`		the tagger's words
content_tags	Paradigms in which participants make no overt report yield a narrower content-specific NCC that contains posterior cortical areas but excludes prefrontal cortex. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[1]`		the tagger's words
content_tags	Gamma synchrony survives or grows during early NREM sleep, anaesthesia and seizures and accompanies unconscious emotional stimuli, so it occurs without consciousness. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[2]`		the tagger's words
content_tags	The P3b is missing in most clearly conscious brain-damaged patients and detects minimally conscious patients very poorly, so it fails as a signature of consciousness. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[3]`		the tagger's words
content_tags	Primary visual cortex V1 is not part of the content-specific NCC for any visual attribute tested so far. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[4]`		the tagger's words
content_tags	Consciousness survives removal of prefrontal cortex: complete bilateral frontal lobectomy and large bilateral prefrontal resections leave it intact. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[5]`		the tagger's words
content_tags	Cerebellar lesions have little effect on consciousness and its contents. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[6]`		the tagger's words
content_tags	Local rather than global EEG activation, especially over the posterior hot zone, may be what matters for consciousness. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[7]`		the tagger's words
content_tags	The perturbational complexity index is the first measure that tracks the level of consciousness across sleep stages, anaesthetics and disorders of consciousness and does so for individual participants. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[8]`		the tagger's words
content_tags	No single brain area turns out to be necessary for being conscious, though areas of the posterior cortical hot zone are the best candidates for both full and content-specific NCC. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[9]`		the tagger's words
content_tags	neural correlates of consciousness (NCC) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: neural correlates of consciousness (NCC)	`content_tags.definitions[0]`		the tagger's words
content_tags	content-specific NCC Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: content-specific NCC	`content_tags.definitions[1]`		the tagger's words
content_tags	full NCC Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: full NCC	`content_tags.definitions[2]`		the tagger's words
content_tags	background conditions for consciousness Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: background conditions for consciousness	`content_tags.definitions[3]`		the tagger's words
content_tags	posterior cortical hot zone Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: posterior cortical hot zone	`content_tags.definitions[4]`		the tagger's words
content_tags	no-report paradigm Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: no-report paradigm	`content_tags.definitions[5]`		the tagger's words
content_tags	perturbational complexity index (PCI) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: perturbational complexity index (PCI)	`content_tags.definitions[6]`		the tagger's words
content_tags	neuronal avalanches Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: neuronal avalanches	`content_tags.definitions[7]`		the tagger's words
content_tags	P3b Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: P3b	`content_tags.definitions[8]`		the tagger's words
content_tags	0.14 — sensitivity of the P3b for identifying minimally conscious patients Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[0]`		the tagger's words
content_tags	40% — proportion of unresponsive, sedated and hypothermic coma patients in whom multivariate decoding still finds a P3b-like component Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[1]`		the tagger's words
content_tags	143 — number of severely brain-injured patients with disorders of consciousness in the structural imaging study of thalamic atrophy Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[2]`		the tagger's words
content_tags	more than one-third — share of awakenings from NREM sleep after which participants report having been conscious, despite reduced neuromodulatory activity Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[3]`		the tagger's words
content_tags	>75 μV — amplitude threshold for the repeated EEG slow waves used to assess loss of consciousness in humans Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[4]`		the tagger's words
content_tags	120– 140 ms — latency of cortical responses to visual stimuli attributed to a feedforward sweep from V1 to extrastriate and inferior temporal cortex Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[5]`		the tagger's words
content_tags	close to 1 million — number of nerve cells in a bee brain, cited when asking whether insects can be conscious Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[6]`		the tagger's words

Interpretive choices

Tags that could not be placed in the text:

none — every tag was located in the text

What was deliberately not tagged, and why, is recorded per paper by the tagger. Where a paper has no such record, this page says so rather than implying that nothing was declined.