Minimally conscious state or cortically mediated state?

Naccache, Lionel

doi:10.1093/brain/awx324

Cited by 135 publications

(121 citation statements)

References 94 publications

(104 reference statements)

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“…Therefore, in terms of neuroanatomy, it is possible to link wakefulness with thalamo-cortical, "vertical" connectivity, while awareness depends on cortico-cortical, "horizontal" connectivity. This is consistent with the recent view by Naccache (Naccache, 2018) that Minimally Conscious State (MCS) patients, who are conscious to some degree, exhibit "Cortically Mediated States", whereas UWS patients do not exhibit such activity, presumably because cortico-cortical connectivity (critical for awareness) is too severely impaired. More specifically, a "critical mass" of information processing requires occurring for the emergence and maintenance of consciousness, which is tightly regulated by thalamo-cortical and cortico-cortical connectivity.…”

Section: Awareness Wakefulness: a Short Review Of Conceptssupporting

confidence: 91%

Decoding the circuitry of consciousness: From local microcircuits to brain-scale networks

Modolo

Hassan

Wendling

et al. 2020

Network Neuroscience

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Identifying the physiological processes underlying the emergence and maintenance of consciousness is one of the most fundamental problems of neuroscience, with implications ranging from fundamental neuroscience to the treatment of patients with disorders of consciousness (DOC). One major challenge is to understand how cortical circuits at drastically different spatial scales, from local networks to brain-scale networks, operate in concert to enable consciousness, and how those processes are impaired in DOC patients. In this review, we attempt to relate available neurophysiological and clinical data with existing theoretical models of consciousness, while linking the micro-and macro-circuit levels. First, we address the relationships between awareness and wakefulness on the one hand, and cortico-cortical, and thalamo-cortical connectivity on the other hand. Second, we discuss the role of three main types of GABAergic interneurons in specific circuits responsible for the dynamical re-organization of functional networks. Third, we explore advances in the functional role of nested oscillations for neural synchronization and communication, emphasizing the importance of the balance between local (high-frequency) and distant (low-frequency) activity for efficient information processing. 2The clinical implications of these theoretical considerations are presented. We propose that such cellular-scale mechanisms could extend current theories of consciousness. IntroductionUnderstanding how consciousness arises from communication among brain regions is a question of the utmost importance in the field of neuroscience in general, and for the diagnosis and treatment of patients suffering from disorders of consciousness (DOC) in particular. The problem of consciousness can be seen as fundamental (e.g.: "What is consciousness? Why do we have subjective, conscious experiences?", such questions are referred to as the "hard" problem of consciousness (Harnad, 1998)) or more empirical (e.g.: "What are the processes associated with the emergence and maintenance of consciousness?", this forms the "soft" problem of consciousness (Harnad, 1998)). In this review, we aim at understanding 1) how brain networks at different scales are involved in enabling and maintaining conscious processes of information transmission and processing related to awareness and wakefulness, and 2) how these mechanisms are related to the disruptions of consciousness in DOC patients.Many theories have been proposed to explain how consciousness originates, ranging from abstract and informational concepts to neurophysiology-based theories. The most widespread theories of consciousness have a fundamental assumption in common: information processing in 3 the human brain networks is inextricably linked with consciousness. A recent paper by Dehaene and colleagues summarizes this principle as follows :"What we call "consciousness" results from specific types of information-processing computations, physically realized by the hardware of the brain."The three main theories o...

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Section: Awareness Wakefulness: a Short Review Of Conceptssupporting

confidence: 91%

Decoding the circuitry of consciousness: From local microcircuits to brain-scale networks

Modolo

Hassan

Wendling

et al. 2020

Network Neuroscience

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“…It is at the core of much of the philosophical confusion, but also, and more importantly, is at the focus of current clinical medical attention. [149,150] "Disorders of Consciousness (DoC)" range from coma and vegetative state (VS)/unresponsive wakefulness (UWS) through minimally conscious states (MCS) to full awareness and cognition. This is then to be compared with normal states of sleep and states induced by sedation and drugs (including psychedelics).…”

Section: Levels and Disorders Of Consciousnessmentioning

confidence: 99%

“…The MCS-label is problematic, because MCS is not a well-defined state: it covers a broad range of responses and needs to be "expanded" in a multi-dimensional space of brain patterns and behaviors. [149][150][151][152] In a recent review in Science: "What is consciousness, and could machines have it? ", Dehaene, Lau, and Kouider [19] discuss how to define different LoCs, and how artificial systems might perceive things.…”

Section: Levels and Disorders Of Consciousnessmentioning

confidence: 99%

Can Biological Quantum Networks Solve NP‐Hard Problems?

Wendin

2019

Adv Quantum Tech

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There is a widespread view that the human brain is so complex that it cannot be efficiently simulated by universal Turing machines, let alone ordinary classical computers. During the last decades the question has therefore been raised whether it is needed to consider quantum effects to explain the imagined cognitive power of a conscious mind. Not surprisingly, the conclusion is that quantum‐enhanced cognition and intelligence are very unlikely to be found in biological brains. Quantum effects may certainly influence signaling pathways at the molecular level in the brain network, like ion ports, synapses, sensors, and enzymes. This might evidently influence the functionality of some nodes and perhaps even the overall intelligence of the brain network, but hardly give it any dramatically enhanced functionality. The conclusion is that biological quantum networks can only approximately solve small instances of nonpolynomial (NP)‐hard problems. On the other hand, artificial intelligence and machine learning implemented in complex dynamical systems based on genuine quantum networks can certainly be expected to show enhanced performance and quantum advantage compared with classical networks. Nevertheless, even quantum networks can only be expected to solve NP‐hard problems approximately. In the end it is a question of precision—Nature is approximate.

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“…This finding was in line with our hypothesis that the isolated hemisphere might contribute in conscious state less compared to the preserved left, and that thalamo-cortical processing plays a necessary role for conscious processing. Also, note that MCS has been recently reinterpreted as a Cortically Mediated State (Naccache, 2018), indicative of a class of behaviors revealing the active contribution of cortical networks, rather than a univocal conscious state. Under such hypothesis, MCS does not relate to consciousness but to a necessary but insufficient condition for conscious processing.…”

Section: /20mentioning

confidence: 99%

Functional cortico-subcortical reorganization after complete hemispheric disconnection for intractable epilepsy

Blauwblomme

Demertzi

Tacchela

et al. 2019

Preprint

Self Cite

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Hemispherotomy is a treatment for drug-resistant epilepsy with the whole hemisphere involved in seizure onset. As recovery mechanisms are still debated, we characterize functional reorganization with multimodal MRI in two children operated on the right hemisphere (RH). We found that interhemispheric functional connectivity was abolished in both patients. The healthy left hemispheres (LH) displayed focal hyperperfusion in motor and limbic areas, and preserved network-level organization. The disconnected RHs were hypoperfused despite sustained network-level organization. Functional connectivity was increased in the left thalamo-cortical loop and between the cerebelli. The classification probability of the RH corresponding to a minimally conscious state was smaller than for the LH. We conclude that after hemispherotomy, neurological rehabilitation is sustained by cortical disinhibition and reinforcement of connectivity driven by subcortical structures in the remaining hemisphere. Our results highlight the effect of vascularization on functional connectivity and raise inquiries about the conscious state of the isolated hemisphere. Clinical outcomes of hemispherectomy for epilepsy in childhood and adolescence. Brain. 2003; 126(Pt 3):556-66. doi: 10.1093/brain/awg052. Funnell MG, Corballis PM, Gazzaniga MS. Insights into the functional specificity of the human corpus callosum. Brain. 2000; 123 ( Pt 5:920-926. doi: 10.1093/brain/123.5.920. Gazzaniga MS. Forty-five years of split-brain research and still going strong. Nature Reviews Neuroscience. 2005; 6(8):653-659. Gold L, Lauritzen M. Neuronal deactivation explains decreased cerebellar blood flow in response to focal cerebral ischemia or suppressed neocortical function.spherectomy for treatment of refractory epilepsy in the pediatric age group: a systematic review. A. The reorganization of sensorimotor function in children after hemispherectomy. A functional MRI and somatosensory evoked potential study.

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Minimally conscious state or cortically mediated state?

Cited by 135 publications

References 94 publications

Decoding the circuitry of consciousness: From local microcircuits to brain-scale networks

Decoding the circuitry of consciousness: From local microcircuits to brain-scale networks

Can Biological Quantum Networks Solve NP‐Hard Problems?

Functional cortico-subcortical reorganization after complete hemispheric disconnection for intractable epilepsy

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