La schizophrénie, pathologie de la conscience? Ou comment les bonnes idées peuvent renaître...

Episodic memory corresponds to a state of consciousness called “autonoetic” which is characterized by the fact the subject is able to consciously remember a past personal life event. The subject is able to recall his autobiographical life, personal and individual and to encompass consciously a future prefiguration by the means of the autonoetic consciousness. The unique and personal characteristics of our memories are linked to relations between conscious remembering and self consciousness. This link can explain that the same event being lived by different subjects can lead to different reported memories. Conscious remembering is a phenomenon that highly contributes to one’s own identity building. Subjective conscious remembering which accompanies the personal memory recuperation is impaired in schizophrenics. This subjective conscious remembering state impairment will provoke the loss or alteration of the capacity of past event revival. Conscious remembering is impaired whereas familiarity is preserved in schizophrenics. Conscious remembering deficit is both quantitative and qualitative: we can observe a fragmentation of the subjective experience, schizophrenics are not able to gather different parts of an event to build a unique representation. This conscious remembering deficit is secondary to an impairment of episodic memories construction. The Jean-Marie Danion’s model places the specific disease deficit at the top of the cognitive building, the consciousness level. This deficit would produce the cognitive dysfunctions shape observed in schizophrenia and would be at the origin of some of the symptoms of the disease.     

意识与麻醉

<正>意识可以定义为"个体觉察自我与环境存在的脑功能状态"也就是说,意识是脑对"存在"的觉察,感知"存在"就是对真实自我和环境的觉察、发生在清醒状态下,对"存在"的觉察是脑的基本功能,也是注意、学习、认知、思维等功能的前提.国际上许多实验室,研究麻醉导致的意识丧失以及麻醉后意识的重启动,来揭示意识的神经基础.最近,Solovey等(J Neurosci,2015,35(30):10866)发现,不同麻醉药物诱导的脑活动模式不同,如果忽略那些具体活动的特征,意识丧失与     

Closure operations in phylogenetics

Closure operations are a useful device in both the theory and practice of tree reconstruction in biology and other areas of classification. These operations take a collection of trees (rooted or unrooted) that classify overlapping sets of objects at their leaves, and infer further tree-like relationships. In this paper we investigate closure operations on phylogenetic trees; both rooted and unrooted; as well as on X-splits, and in a general abstract setting. We derive a number of new results, particularly concerning the completeness (and incompleteness) and complexity of various types of closure rules.     

A computable expression of closure to efficient causation

In this paper, we propose a mathematical expression of closure to efficient causation in terms of λ-calculus; we argue that this opens up the perspective of developing principled computer simulations of systems closed to efficient causation in an appropriate programming language. An important implication of our formulation is that, by exhibiting an expression in λ-calculus, which is a paradigmatic formalism for computability and programming, we show that there are no conceptual or principled problems in realizing a computer simulation or model of closure to efficient causation. We conclude with a brief discussion of the question whether closure to efficient causation captures all relevant properties of living systems. We suggest that it might not be the case, and that more complex definitions could indeed create crucial some obstacles to computability.     

Consciousness: here,there and everywhere?

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.     

The Ferrier Lecture 1995 behind the seen: the functional specialization of the brain in space and time

The visual brain consists of many different visual areas, which are functionally specialized to process and perceive different attributes of the visual scene. However, the time taken to process different attributes varies; consequently, we see some attributes before others. It follows that there is a perceptual asynchrony and hierarchy in visual perception. Because perceiving an attribute is tantamount to becoming conscious of it, it follows that we become conscious of different attributes at different times. Visual consciousness is therefore distributed in time. Given that we become conscious of different visual attributes because of activity at different, functionally specialized, areas of the visual brain, it follows that visual consciousness is also distributed in space. Therefore, visual consciousness is not a single unified entity, but consists of many microconsciousnesses.     

Hallucinations on demand: the utility of experimentally induced phenomena in hallucination research

Despite the desire to delve deeper into hallucinations of all types, methodological obstacles have frustrated development of more rigorous quantitative experimental techniques, thereby hampering research progress. Here, we discuss these obstacles and, with reference to visual phenomena, argue that experimentally induced phenomena (e.g. hallucinations induced by flickering light and classical conditioning) can bring hallucinations within reach of more objective behavioural and neural measurement. Expanding the scope of hallucination research raises questions about which phenomena qualify as hallucinations, and how to identify phenomena suitable for use as laboratory models of hallucination. Due to the ambiguity inherent in current hallucination definitions, we suggest that the utility of phenomena for use as laboratory hallucination models should be represented on a continuous spectrum, where suitability varies with the degree to which external sensory information constrains conscious experience. We suggest that existing strategies that group pathological hallucinations into meaningful subtypes based on hallucination characteristics (including phenomenology, disorder and neural activity) can guide extrapolation from hallucination models to other hallucinatory phenomena. Using a spectrum of phenomena to guide scientific hallucination research should help unite the historically separate fields of psychophysics, cognitive neuroscience and clinical research to better understand and treat hallucinations, and inform models of consciousness.This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.     

Metamemory as evidence of animal consciousness: the type that does the trick

The question of whether non-human animals are conscious is of fundamental importance. There are already good reasons to think that many are, based on evolutionary continuity and other considerations. However, the hypothesis is notoriously resistant to direct empirical test. Numerous studies have shown behaviour in animals analogous to consciously-produced human behaviour. Fewer probe whether the same mechanisms are in use. One promising line of evidence about consciousness in other animals derives from experiments on metamemory. A study by Hampton (Proc Natl Acad Sci USA 98(9):5359–5362, 2001) suggests that at least one rhesus macaque can use metamemory to predict whether it would itself succeed on a delayed matching-to-sample task. Since it is not plausible that mere meta-representation requires consciousness, Hampton’s study invites an important question: what kind of metamemory is good evidence for consciousness? This paper argues that if it were found that an animal had a memory trace which allowed it to use information about a past perceptual stimulus to inform a range of different behaviours, that would indeed be good evidence that the animal was conscious. That functional characterisation can be tested by investigating whether successful performance on one metamemory task transfers to a range of new tasks. The paper goes on to argue that thinking about animal consciousness in this way helps in formulating a more precise functional characterisation of the mechanisms of conscious awareness.     

睡眠纺锤波在植物状态病人预后判别中的价值研究

目的:探讨脑电图睡眠纺锤波在植物状态病人预后判别中的价值。方法:在长程脑电监测下观察植物状态病人的睡眠纺锤波,与其意识恢复进行相关性分析,并预测患者意识恢复的敏感性、特异性及准确性。结果:28例患者中,12例有纺锤波,其中9例意识恢复;16例无纺锤波患者中,14例未恢复意识。纺锤波的有无与患者意识恢复有相关性,P值<0.01。脑电图睡眠纺锤波对植物状态患者意识恢复判断的敏感性(83.25%)、特异性(81.82%)、准确性(82.14%)。结论:脑电图睡眠纺锤波可较准确预测植物状态患者的意识恢复能力,可作为临床评估植物状态患者意识恢复能力的辅助方法。     

Visual perception from the perspective of a representational,non-reductionistic,level-dependent account of perception and conscious awareness

This article proposes a new model to interpret seemingly conflicting evidence concerning the correlation of consciousness and neural processes. Based on an analysis of research of blindsight and subliminal perception, the reorganization of elementary functions and consciousness framework suggests that mental representations consist of functions at several different levels of analysis, including truly localized perceptual elementary functions and perceptual algorithmic modules, which are interconnections of the elementary functions. We suggest that conscious content relates to the ‘top level’ of analysis in a ‘situational algorithmic strategy’ that reflects the general state of an individual. We argue that conscious experience is intrinsically related to representations that are available to guide behaviour. From this perspective, we find that blindsight and subliminal perception can be explained partly by too coarse-grained methodology, and partly by top-down enhancing of representations that normally would not be relevant to action.     

Rhythms of Consciousness: Binocular Rivalry Reveals Large-Scale Oscillatory Network Dynamics Mediating Visual Perception

Consciousness has been proposed to emerge from functionally integrated large-scale ensembles of gamma-synchronous neural populations that form and dissolve at a frequency in the theta band. We propose that discrete moments of perceptual experience are implemented by transient gamma-band synchronization of relevant cortical regions, and that disintegration and reintegration of these assemblies is time-locked to ongoing theta oscillations. In support of this hypothesis we provide evidence that (1) perceptual switching during binocular rivalry is time-locked to gamma-band synchronizations which recur at a theta rate, indicating that the onset of new conscious percepts coincides with the emergence of a new gamma-synchronous assembly that is locked to an ongoing theta rhythm; (2) localization of the generators of these gamma rhythms reveals recurrent prefrontal and parietal sources; (3) theta modulation of gamma-band synchronization is observed between and within the activated brain regions. These results suggest that ongoing theta-modulated-gamma mechanisms periodically reintegrate a large-scale prefrontal-parietal network critical for perceptual experience. Moreover, activation and network inclusion of inferior temporal cortex and motor cortex uniquely occurs on the cycle immediately preceding responses signaling perceptual switching. This suggests that the essential prefrontal-parietal oscillatory network is expanded to include additional cortical regions relevant to tasks and perceptions furnishing consciousness at that moment, in this case image processing and response initiation, and that these activations occur within a time frame consistent with the notion that conscious processes directly affect behaviour.     

The neural correlate of consciousness

I propose that we are only aware of changes in our underlying cognition. This hypothesis is based on four lines of evidence. (1) Without changes in visual input (including fixational eye movements), static images fade from awareness. (2) Consciousness appears to be continuous, but is actually broken up into discrete cycles of cognition. Without continuity, conscious awareness disintegrates into a series of isolated cycles. The simplest mechanism for creating continuity is to track the changes between the cycles. (3) While these conscious vectors are putative, they have a clear source: the dorsolateral prefrontal cortex (DLPFC). The DLPFC is active during awareness of changes, and this awareness is disrupted by repetitive transcranial magnetic stimulation. (4) When the DLPFC and the orbital and inferior parietal cortices are deactivated during dreaming, conscious awareness is absent even though the rest of the brain is active. Moreover, Lau and Passingham showed that activation of the DLPFC, but no other brain region, correlates with awareness. In summary, if the DLPFC and conscious vectors are the neural correlate of consciousness, then we are only aware of changes in our underlying cognition. The glue that holds conscious awareness together is conscious awareness.     

Does consciousness overflow cognitive access? Novel insights from the new phenomenon of attribute amnesia

The moment we open our eyes, we experience a rich and detailed visual world, but the amount of information available to report is rather limited. This dissociation relates to a major debate regarding the nature of visual consciousness. The overflow argument suggests that our conscious experience is quite rich and far beyond what can be reported, standing in sharp contrast to the nooverflow argument that visual consciousness is severely impoverished and limited to what can be reported. In this paper, we systematically reviewed existing evidence in favor of the overflow argument, including studies of several variations of the iconic memory paradigm and the divided attention paradigm, as well as studies of neural correlates of consciousness. Simultaneously,we expounded some critical objections and alternative interpretations to such evidence, as well as some opposing evidence.Finally, we introduced a series of our recent studies based on a striking phenomenon of attribute amnesia, which we believe could provide new insight into the overflow view of visual consciousness.     

Single-neuron theory of consciousness

By most accounts, the mind arises from the integrated activity of large populations of neurons distributed across multiple brain regions. A contrasting model is presented in the present paper that places the mind/brain interface not at the whole brain level but at the level of single neurons. Specifically, it is proposed that each neuron in the nervous system is independently conscious, with conscious content corresponding to the spatial pattern of a portion of that neuron's dendritic electrical activity. For most neurons, such as those in the hypothalamus or posterior sensory cortices, the conscious activity would be assumed to be simple and unable to directly affect the organism's macroscopic conscious behavior. For a subpopulation of layer 5 pyramidal neurons in the lateral prefrontal cortices, however, an arrangement is proposed to be present such that, at any given moment: (i) the spatial pattern of electrical activity in a portion of the dendritic tree of each neuron in the subpopulation individually manifests a complexity and diversity sufficient to account for the complexity and diversity of conscious experience; (ii) the dendritic trees of the neurons in the subpopulation all contain similar spatial electrical patterns; (iii) the spatial electrical pattern in the dendritic tree of each neuron interacts non-linearly with the remaining ambient dendritic electrical activity to determine the neuron's overall axonal response; (iv) the dendritic spatial pattern is reexpressed at the population level by the spatial pattern exhibited by a synchronously firing subgroup of the conscious neurons, thereby providing a mechanism by which conscious activity at the neuronal level can influence overall behavior. The resulting scheme is one in which conscious behavior appears to be the product of a single macroscopic mind, but is actually the integrated output of a chorus of minds, each associated with a different neuron.     

Animal Consciousness: Some Philosophical, Methodological, and Evolutionary Problems

No consensus exists concerning the mechanisms, distribution,or adaptive significance of consciousness. Agreement on anyone of these issues would aid in resolving others. Given a reliablebehavioral or neuroanatomical test for consciousness, we couldmap its distribution and describe its evolution. Conversely,if we knew its distribution, we could assess its adaptive valueand look for similarly distributed neuroanatomies to help usget at its mechanisms. Morgan's Canon—the rule that we should avoid attributinghumanlike mental states to other animals whenever possible—impedesthe use of the comparative method in unraveling this knot. Ifinterpreted in this context as a parsimony criterion, Morgan'sCanon is logically equivalent to epiphenomenalism. It is parsimoniousif and only if conscious mental events play no causal role inhuman behavior and human consciousness has no adaptive significance.Rejecting this conclusion entails rejecting the parsimony interpretationof Morgan's Canon.     

Consciousness without cortex

Sensory consciousness — the awareness and ability to report subjective experiences — is a property of biological nervous systems that has evolved out of unconscious processing over hundreds of millions of years. From which brain structures and based on which mechanisms can conscious experience emerge? Based on the body of work in human and nonhuman primates, the emergence of consciousness is intimately associated with the workings of the mammalian cerebral cortex with its specific cell types and layered structure. However, recent neurophysiological recordings demonstrate a neuronal correlate of consciousness in the pallial endbrain of crows. These telencephalic integration centers in birds originate embryonically from other pallial territories, lack a layered architecture characteristic for the cerebral cortex, and exhibit independently evolved pallial cell types. This argues that the mammalian cerebral cortex is not a prerequisite for consciousness to emerge in all vertebrates. Rather, it seems that the anatomical and physiological principles of the telencephalic pallium offer this structure as a brain substrate for consciousness to evolve independently across vertebrate phylogeny.     

Structuring process and closure principle in spatial and temporal reproduction tasks

The goal of the experiment reported was to replicate the previous Sarrazin’s (2000) study in order to verify, with an adequate methodological procedure, whether or not the closure principle applied in spatial and temporal reproduction tasks. The hypothesis defended was that the closure of the pattern is an intrinsic property of the structuring process in spatial memory. The stimuli consisted of eight visually presented dots that appeared sequentially with inter-dot distances corresponding to inter-dot durations. After a learning phase, participants reproduced the spatial (space condition) or temporal (time condition) characteristics of the target 60 times in succession. We analyzed the variance level for both element location and Inter-Element-Interval (IEI) on spatial and temporal responses. Two main results emerge from this experiment: (1) the critical dependency of the closure principle to the nature (spatial or temporal) of the response, (2) the importance to consider both locations and intervals as complementary information. These results are discussed in the light of physical system, in particular in term of compensation phenomenon and we proposed a mathematical model that replicates the qualitative feature of variance for both space and time conditions.     

Reviving Brain Death: A Functionalist View

Recently both whole brain death (WBD) and higher brain death (HBD) have come under attack. These attacks, we argue, are successful, leaving supporters of both views without a firm foundation. This state of affairs has been described as “the death of brain death.” Returning to a cardiopulmonary definition presents problems we also find unacceptable. Instead, we attempt to revive brain death by offering a novel and more coherent standard of death based on the permanent cessation of mental processing. This approach works, we claim, by being functionalist instead of being based in biology, consciousness, or personhood. We begin by explaining why an objective biological determination of death fails. We continue by similarly rejecting current arguments offered in support of HBD, which rely on consciousness and/or personhood. In the final section, we explain and defend our functionalist view of death. Our definition centers on mental processing, both conscious and preconscious or unconscious. This view provides the philosophical basis of a functional definition that most accurately reflects the original spirit of brain death when first proposed in the Harvard criteria of 1968.     

Systematization of a set of closure techniques

Approximations in population dynamics are gaining popularity since stochastic models in large populations are time consuming even on a computer. Stochastic modeling causes an infinite set of ordinary differential equations for the moments. Closure models are useful since they recast this infinite set into a finite set of ordinary differential equations. This paper systematizes a set of closure approximations. We develop a system, which we call a power p closure of n moments, where 0≤p≤n. [Keeling, 2000a] and [Keeling, 2000b] approximation with third order moments is shown to be an instantiation of this system which we call a power 3 closure of 3 moments. We present an epidemiological example and evaluate the system for third and fourth moments compared with Monte Carlo simulations.     

Consciousness related neural events viewed as brain state space transitions

This theoretical and speculative essay addresses a categorical distinction between neural events of sensory-motor cognition and those presumably associated with consciousness. It proposes to view this distinction in the framework of the branch of Statistical Physics currently referred to as Modern Critical Theory (Stanley, Introduction to phase transitions and critical phenomena, 1987; Marro and Dickman, Nonequilibrium phase transitions in lattice, 1999). Based on established landmarks of brain dynamics, network configurations and their role for conveying oscillatory activity of certain frequencies bands, the question is examined: what kind of state space transitions can systems with these properties undergo, and could the relation between neural processes of sensory-motor cognition and those of events in consciousness be of the same category as is characterized by state transitions in non-equilibrium physical systems? Approaches for empirical validation of this view by suitably designed brain imaging studies, and for computational simulations of the proposed principle are discussed.