195 research outputs found
Correction to: Actigraphy assessments of circadian sleep-wake cycles in the Vegetative and Minimally Conscious States.
The original article [1] contains an error affecting the actigraphy time-stamps throughout the article, particularly in Table 1
Disruption in structural–functional network repertoire and time-resolved subcortical fronto-temporoparietal connectivity in disorders of consciousness
Understanding recovery of consciousness and elucidating its underlying mechanism is believed to be crucial in the field of basic neuroscience and medicine. Ideas such as the global neuronal workspace (GNW) and the mesocircuit theory hypothesize that failure of recovery in conscious states coincide with loss of connectivity between subcortical and frontoparietal areas, a loss of the repertoire of functional networks states and metastable brain activation. We adopted a time-resolved functional connectivity framework to explore these ideas and assessed the repertoire of functional network states as a potential marker of consciousness and its potential ability to tell apart patients in the unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS). In addition, the prediction of these functional network states by underlying hidden spatial patterns in the anatomical network, that is so-called eigenmodes, was supplemented as potential markers. By analysing time-resolved functional connectivity from functional MRI data, we demonstrated a reduction of metastability and functional network repertoire in UWS compared to MCS patients. This was expressed in terms of diminished dwell times and loss of nonstationarity in the default mode network and subcortical fronto-temporoparietal network in UWS compared to MCS patients. We further demonstrated that these findings co-occurred with a loss of dynamic interplay between structural eigenmodes and emerging time-resolved functional connectivity in UWS. These results are, amongst others, in support of the GNW theory and the mesocircuit hypothesis, underpinning the role of time-resolved thalamo-cortical connections and metastability in the recovery of consciousness
A neurophenomenological approach to non-ordinary states of consciousness: hypnosis, meditation, and psychedelics
No contemporary unifying framework has been provided for the study of non-ordinary states of consciousness (NSCs) despite increased interest in hypnosis, meditation, and psychedelics. NSCs induce shifts in experiential contents (what appears to the experiencer) and/or structure (how it appears). This can allow the investigation of the plastic and dynamic nature of experience from a multiscale perspective that includes mind, brain, body, and context. We propose a neurophenomenological (NP) approach to the study of NSCs which highlights their role as catalysts of transformation in clinical practice by refining our understanding of the relationships between experiential (subjective) and neural dynamics. We outline the ethical implications of the NP approach for standard conceptions of health and pathology as well as the crucial role of experience-based know-how in NSC-related research and application
Disembodied Mind: Cortical Changes Following Brainstem Injury in Patients with Locked-in Syndrome
Locked-in syndrome (LIS) following ventral brainstem damage is the most severe form of motor disability. Patients are
completely entrapped in an unresponsive body despite consciousness is preserved. Although the main feature of LIS is this extreme
motor impairment, minor non-motor dysfunctions such as motor imagery defects and impaired emotional recognition have been
reported suggesting an alteration of embodied cognition, defined as the effects that the body and its performances may have on
cognitive domains. We investigated the presence of structural cortical changes in LIS, which may account for the reported cognitive
dysfunctions. For this aim, magnetic resonance imaging scans were acquired in 11 patients with LIS (6 males and 5 females; mean
age: 52.3\ub15.2SD years; mean time interval from injury to evaluation: 9\ub11.2SD months) and 44 healthy control subjects matching
patients for age, sex and education. Freesurfer software was used to process data and to estimate cortical volumes in LIS patients as
compared to healthy subjects. Results showed a selective cortical volume loss in patients involving the superior frontal gyrus, the
pars opercularis and the insular cortex in the left hemisphere, and the superior and medium frontal gyrus, the pars opercularis, the
insular cortex, and the superior parietal lobule in the right hemisphere. As these structures are typically associated with the mirror
neuron system, which represents the neural substrate for embodied simulation processes, our results provide neuroanatomical support
for potential disembodiment in LIS
Complexity of multi-dimensional spontaneous EEG decreases during propofol induced general anaesthesia
Emerging neural theories of consciousness suggest a correlation between a specific type of neural dynamical complexity and the level of consciousness: When awake and aware, causal interactions between brain regions are both integrated (all regions are to a certain extent connected) and differentiated (there is inhomogeneity and variety in the interactions). In support of this, recent work by Casali et al (2013) has shown that Lempel-Ziv complexity correlates strongly with conscious level, when computed on the EEG response to transcranial magnetic stimulation. Here we investigated complexity of spontaneous high-density EEG data during propofol-induced general anaesthesia. We consider three distinct measures: (i) Lempel-Ziv complexity, which is derived from how compressible the data are; (ii) amplitude coalition entropy, which measures the variability in the constitution of the set of active channels; and (iii) the novel synchrony coalition entropy (SCE), which measures the variability in the constitution of the set of synchronous channels. After some simulations on Kuramoto oscillator models which demonstrate that these measures capture distinct ‘flavours’ of complexity, we show that there is a robustly measurable decrease in the complexity of spontaneous EEG during general anaesthesia
Allocating the Burdens of Climate Action: Consumption-Based Carbon Accounting and the Polluter-Pays Principle
Action must be taken to combat climate change. Yet, how the costs of climate action should be allocated among states remains a question. One popular answer—the polluter-pays principle (PPP)—stipulates that those responsible for causing the problem should pay to address it. While intuitively plausible, the PPP has been subjected to withering criticism in recent years. It is timely, following the Paris Agreement, to develop a new version: one that does not focus on historical production-based emissions but rather allocates climate burdens in proportion to each state’s annual consumption-based emissions. This change in carbon accounting results in a fairer and more environmentally effective principle for distributing climate duties
Stratification of unresponsive patients by an independently validated index of brain complexity.
OBJECTIVE:
Validating objective, brain-based indices of consciousness in behaviorally unresponsive patients represents a challenge due to the impossibility of obtaining independent evidence through subjective reports. Here we address this problem by first validating a promising metric of consciousness-the Perturbational Complexity Index (PCI)-in a benchmark population who could confirm the presence or absence of consciousness through subjective reports, and then applying the same index to patients with disorders of consciousness (DOCs).
METHODS:
The benchmark population encompassed 150 healthy controls and communicative brain-injured subjects in various states of conscious wakefulness, disconnected consciousness, and unconsciousness. Receiver operating characteristic curve analysis was performed to define an optimal cutoff for discriminating between the conscious and unconscious conditions. This cutoff was then applied to a cohort of noncommunicative DOC patients (38 in a minimally conscious state [MCS] and 43 in a vegetative state [VS]).
RESULTS:
We found an empirical cutoff that discriminated with 100% sensitivity and specificity between the conscious and the unconscious conditions in the benchmark population. This cutoff resulted in a sensitivity of 94.7% in detecting MCS and allowed the identification of a number of unresponsive VS patients (9 of 43) with high values of PCI, overlapping with the distribution of the benchmark conscious condition.
INTERPRETATION:
Given its high sensitivity and specificity in the benchmark and MCS population, PCI offers a reliable, independently validated stratification of unresponsive patients that has important physiopathological and therapeutic implications. In particular, the high-PCI subgroup of VS patients may retain a capacity for consciousness that is not expressed in behavior
Recommended from our members
A neurophenomenological approach to non-ordinary states of consciousness: hypnosis, meditation, and psychedelics
Copyright © 2023 The Authors. No contemporary unifying framework has been provided for the study of non-ordinary states of consciousness (NSCs) despite increased interest in hypnosis, meditation, and psychedelics. NSCs induce shifts in experiential contents (what appears to the experiencer) and/or structure (how it appears). This can allow the investigation of the plastic and dynamic nature of experience from a multiscale perspective that includes mind, brain, body, and context. We propose a neurophenomenological (NP) approach to the study of NSCs which highlights their role as catalysts of transformation in clinical practice by refining our understanding of the relationships between experiential (subjective) and neural dynamics. We outline the ethical implications of the NP approach for standard conceptions of health and pathology as well as the crucial role of experience-based know-how in NSC-related research and application.This research was supported by Mind and Life Europe, the LABEX CORTEX of Université de Lyon (ANR-11-LABX-0042) within the 'Investissements d'Avenir' program (ANR-11-IDEX-0007) (to A.L.), by a European Research Council grant (ERC-Consolidator 617739-BRAINandMINDFULNESS) (A.L.), BIAL Foundation (260/16; P.R.B. and A.L.; Grant Nos 261/18 and 344/20 to O.G.), the EU Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie grant agreement 749582 (Neural Correlates of Self/NeuCoSe; P.R.B) and under the Specific Grant Agreement No. 945539 (Human Brain Project SGA3), University and University Hospital of Liège, Benoit Foundation (Bruxelles), and King's College London (King's Together Fund research grant 'Towards Experiential Neuroscience Paradigm'; E.A.), the Belgian Foundation Against Cancer (Grant Nos 2017064 and C/2020/1357), the Télévie, Wallonia as part of a program of the BioWin Health Cluster framework and the Swiss Neuromatrix Foundation (Grant No 2020-0201 to F.X.V.). C.T. is funded by donors of the Centre for Psychedelic Research; O.G. and S.L. are supported by the Fonds de la Recherche Scientifique (FRS)/Fonds National de la Recherche Scientifique (FNRS). The authors would like to thank Adeline Deward (RISE Illustration) for professional rendering of the figures
Response to comment on "preserved feedforward but impaired top-down processes in the vegetative state".
King et al. raise some technical issues about our recent study showing impaired top-down processes in the vegetative state. We welcome the opportunity to provide more details about our methods and results and to resolve their concerns. We substantiate our interpretation of the results and provide a point-by-point response to the issues raised.Peer reviewe
- …