The neural correlates of consciousness in sleep: A no-task, within-state paradigm

The neural correlates of consciousness in sleep: A no-task, within-state paradigm Siclari LaRocque Bernardi Postle Tononi

Tag layer of the DHSS Meta-Tagging Project. The article text is reproduced from the staged copy named in sourceDesc and is not altered; the tags are held separately in standOff so that overlapping and nested spans are preserved.

The neural correlates of consciousness in sleep: A no-task, within-state paradigm 2014 bioRxiv 10.1101/012443 Siclari2014-the-neural-correlates-of-consciousness-in-sl Siclari2014-the-neural-correlates-of-consciousness-in-sl.txt, the project's staged copy e958b275c0cf378787dfdccc433dfe4492f94463 not-redistributable neuroscience

the paper's own words

the tag layer; a sentence written by the tagger about the paper, always anchored to a quotation but not itself a quotation

0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them existence Quotation withheld because this record is not cleared for redistribution. dreaming as conscious experience during sleep Quotation withheld because this record is not cleared for redistribution. electrophysiology electrophysiology Quotation withheld because this record is not cleared for redistribution. mechanisms Conscious experience during sleep requires local activation (loss of low-frequency, bistable mode) of the posterior hot zone, which is why dreaming can occur in NREM and REM alike regardless of the EEG in the rest of cortex Quotation withheld because this record is not cleared for redistribution. mechanisms Low-frequency (1-4 Hz) activity indexes neuronal down-states and bistability, which block stable causal interaction between cortical areas and so abolish experience Quotation withheld because this record is not cleared for redistribution. mechanisms Once the hot zone is out of its low-frequency mode, which specific neuronal groups fire strongly determines which contents are experienced, as in waking perception Quotation withheld because this record is not cleared for redistribution. The hot zone was identified by averaging across many awakenings and subjects, so individual episodes of experience may involve additional regions. what this limits: the anatomical completeness of the hot zone: SINCE THE POSTERIOR HOT ZONE WAS HIGHLIGHTED BY AVERAGING EEG RECORDINGS PRECEDING MANY AWAKENINGS FROM MANY SUBJECTS, THE FULL NEURAL CORRELATES OF EXPERIENCES IN SLEEP COULD OCCASIONALLY INCLUDE ADDITIONAL BRAIN REGIONS Quotation withheld because this record is not cleared for redistribution. Parts of the posterior hot zone may support unconscious dream-generating processes rather than experience itself. what this limits: the interpretation of the hot zone as supporting experience: WE CANNOT RULE OUT THAT [it] MAY INCLUDE ... AREAS THAT MIGHT SUPPORT UNCONSCIOUS ASPECTS OF DREAM GENERATION Quotation withheld because this record is not cleared for redistribution. Source modelling does not fully remove volume conduction, which inflates absolute low-frequency power values. what this limits: the absolute low-frequency power values: SOURCE MODELING STRONGLY REDUCES BUT DOES NOT COMPLETELY ELIMINATE THE EFFECTS OF VOLUME CONDUCTION Quotation withheld because this record is not cleared for redistribution. The behavioural state does not settle whether there was an experience, and the paper says so of both the traditional EEG features and the neuroimaging correlates. what this limits: sleep stage as an indicator of whether a subject was having an experience: the paper states this cannot be determined from behavioural state, traditional EEG features or neuroimaging correlates Quotation withheld because this record is not cleared for redistribution. The identification the field worked with is reported as failing in both directions: dreams are absent from some REM awakenings and present in NREM sleep. what this limits: REM sleep as the state of dreaming: the paper reports a consistent minority of REM awakenings with no reported experience, and dreaming occurring in NREM sleep Quotation withheld because this record is not cleared for redistribution. a longer 20-second pre-awakening window used for the experience/no-experience contrast than the 0 to -8s windows used for content-specific contrasts eliminates: a report being assigned to the wrong stretch of sleep - subjects could tie CONTENT to a moment but not the bare presence or absence of an experience, so that contrast is given more room · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. dreaming dreaming Quotation withheld because this record is not cleared for redistribution. REM sleep REM sleep Quotation withheld because this record is not cleared for redistribution. no experience no experience Quotation withheld because this record is not cleared for redistribution. absence of a dream report - AS NO EXPERIENCE (NE): the subject reports not experiencing anything Quotation withheld because this record is not cleared for redistribution. absence of a dream report - AS EXPERIENCE WITHOUT RECALL (DEWR): the subject reports experiencing something but cannot remember the content, which is a different state from having had none Quotation withheld because this record is not cleared for redistribution. dreaming - traditionally IDENTIFIED WITH REM sleep and its wake-like high-frequency EEG, an identification the paper reports as broken because dreaming also occurs in NREM sleep Quotation withheld because this record is not cleared for redistribution. extends → the fMRI dream-content decoding study cited as ref. 43 (a wake-trained pattern classifier decoding content reported at the wake–sleep transition) Quotation withheld because this record is not cleared for redistribution. contradicts → the influential neuroimaging-derived notion (ref. 54) that the neural correlates of consciousness correspond to a broad fronto-parietal network differs in: THE AXIS IS THE PARADIGM, AND IT IS NAMED IN THE SAME SENTENCE AS THE CONCLUSION. 'Quotation withheld' The fronto-parietal result is not called wrong - it is attributed to paradigms that require a task and a report, which this one removes. A bare 'contradicts' records a dispute about ANATOMY; the parameter shows it is a dispute about METHOD. Quotation withheld because this record is not cleared for redistribution. dreaming —distinct-from→ REM sleep dreaming REM sleep strength of the relation: 1 Quotation withheld because this record is not cleared for redistribution. repeated-measures ANOVA repeated-measures ANOVA Quotation withheld because this record is not cleared for redistribution. ANCOVA ANCOVA Quotation withheld because this record is not cleared for redistribution. paired t-test paired t-test Quotation withheld because this record is not cleared for redistribution. Spearman rank correlation Spearman rank correlation Quotation withheld because this record is not cleared for redistribution. permutation test permutation test Quotation withheld because this record is not cleared for redistribution. nonparametric multiple-comparison correction nonparametric multiple-comparison correction Quotation withheld because this record is not cleared for redistribution. Kolmogorov-Smirnov normality test Kolmogorov-Smirnov normality test Quotation withheld because this record is not cleared for redistribution. false discovery rate correction false discovery rate correction Quotation withheld because this record is not cleared for redistribution. spectral power density estimation (Welch periodogram) spectral power density estimation (Welch periodogram) Quotation withheld because this record is not cleared for redistribution. general linear model general linear model Quotation withheld because this record is not cleared for redistribution. standard deviation standard deviation Quotation withheld because this record is not cleared for redistribution. F-test for interaction F-test for interaction Quotation withheld because this record is not cleared for redistribution. In both NREM and REM sleep, dreaming was associated with a local decrease in low-frequency activity in posterior cortical regions. Quotation withheld because this record is not cleared for redistribution. Reports of having experienced something without recalling its content also showed the posterior low-frequency decrease relative to no-experience reports, so the posterior marker tracks having an experience rather than remembering it. Quotation withheld because this record is not cleared for redistribution. Awakenings triggered in real time by a bispectral low/high-frequency threshold over the posterior hot zone predicted the presence or absence of dreaming in NREM sleep with 87% overall accuracy (91.6% for dreaming predictions, 80.7% for no-experience predictions). Quotation withheld because this record is not cleared for redistribution. High-frequency activity correlated with the thinking dimension of dreams in frontal regions and with the perceiving dimension in parietal, occipital and temporal areas. Quotation withheld because this record is not cleared for redistribution. Dreams containing faces were accompanied by increased high-frequency activity in a temporo-occipital region closely matching the fusiform face area. Quotation withheld because this record is not cleared for redistribution. Dreams with a definite spatial setting showed increased high-frequency activity in right posterior parietal cortex, an area supporting spatial perception and visuo-spatial attention in wakefulness. Quotation withheld because this record is not cleared for redistribution. Dreams containing speech showed increased high-frequency activity in a left posterior temporal region corresponding to Wernicke's area. Quotation withheld because this record is not cleared for redistribution. The results showed no reliable hemispheric asymmetry, apart from a borderline right-sided effect for the high-frequency dreaming-versus-no-experience contrast in REM sleep. Quotation withheld because this record is not cleared for redistribution. The low- and high-frequency effects on dreaming survived control for participant age, with a significant main effect of report type and no age effect. Quotation withheld because this record is not cleared for redistribution. Because the correlate of experience was confined to a posterior region rather than a lateral fronto-parietal network, the authors conclude the neural correlate of consciousness is posterior rather than fronto-parietal. Quotation withheld because this record is not cleared for redistribution. posterior cortical 'hot zone' posterior cortical 'hot zone' Quotation withheld because this record is not cleared for redistribution. bispectral threshold bispectral threshold Quotation withheld because this record is not cleared for redistribution. EEG slow waves EEG slow waves Quotation withheld because this record is not cleared for redistribution. dreaming experience dreaming experience Quotation withheld because this record is not cleared for redistribution. DEWR DEWR Quotation withheld because this record is not cleared for redistribution. no experience no experience Quotation withheld because this record is not cleared for redistribution. type of report type of report Quotation withheld because this record is not cleared for redistribution. low-frequency power low-frequency power Quotation withheld because this record is not cleared for redistribution. high-frequency band power high-frequency band power Quotation withheld because this record is not cleared for redistribution. hemisphere hemisphere Quotation withheld because this record is not cleared for redistribution. age age Quotation withheld because this record is not cleared for redistribution. 87% — Overall accuracy of real-time prediction of the presence or absence of dreaming in NREM sleep from posterior hot-zone EEG Quotation withheld because this record is not cleared for redistribution. N=32, 233 awakenings; N=7, 815 awakenings — Sample sizes for experiment 1 (many naive subjects, few awakenings each) and experiment 2 (few trained subjects, many awakenings each) Quotation withheld because this record is not cleared for redistribution. 84 — Total number of algorithm-triggered awakenings in the real-time prediction experiment Quotation withheld because this record is not cleared for redistribution. p=0.023 — Region-of-interest test showing higher high-frequency activity in the right fusiform face area for dreams containing faces Quotation withheld because this record is not cleared for redistribution. r>0.14 — Correlation threshold at which high-frequency power tracked the thinking-versus-perceiving rating of REM dreams Quotation withheld because this record is not cleared for redistribution. p=0.003 / p=0.005 — Main effect of report type on low-frequency and high-frequency activity after controlling for age Quotation withheld because this record is not cleared for redistribution. p= 0.046 — The single borderline hemispheric lateralization effect, for high-frequency DE-vs-NE in REM sleep Quotation withheld because this record is not cleared for redistribution.

The full text of this article is not redistributable, so it is not included here. The evidence sentences are withheld with it; the tag layer and its grounding status remain. The article itself is at https://doi.org/10.1101/012443.