This is the first in a series of instalments aiming at a minimal model explanation for conscious experience, taking the phenomenal character of “pure consciousness” or “pure awareness” in meditation as its entry point. It develops the concept of “minimal phenomenal experience” as a candidate for the simplest form of consciousness, substantiating it by extracting six semantic constraints from the existing literature and using sixteen phenomenological case-studies to incrementally flesh out the new working concept. One empirical hypothesis is that the (...) phenomenological prototype of “pure awareness”, to which all such reports refer, really is the content of a predictive model, namely, a Bayesian representation of tonic alertness. On a more abstract conceptual level, it can be described as a model of an unpartitioned epistemic space. (shrink)

Contemporary theories of consciousness are based on widely different concepts of its nature, most or all of which probably embody aspects of the truth about it. Starting with a concept of consciousness indicated by the phrase “the feeling of what happens” (the title of a book by Antonio Damásio), we attempt to build a framework capable of supporting and resolving divergent views. We picture consciousness in terms of Reality experiencing itself from the perspective of cognitive agents. Each conscious experience is (...) regarded as composed of momentary feeling events that are combined by recognition and evaluation into extended conscious episodes that bind cognitive contents with a wide range of apparent durations (0.1 secs to 2 or more secs, for us humans, depending on circumstances and context). Three necessary conditions for the existence of consciousness are identified: a) a ground of Reality, envisaged as an universal field of potentiality encompassing all possible manifestations, whether material or 'mental'; b) a transitional zone, leading to; c) a manifest world with its fundamental divisions into material, 'informational' and quale-endowed aspects. We explore ideas about the nature of these necessary conditions, how they may relate to one another and whether our suggestions have empirical implications. (shrink)

Arguably, emotion is always valenced—either pleasant or unpleasant—and dependent on the pleasure system. This system serves adaptive evolutionary functions; relying on separable wanting, liking, and learning neural mechanisms mediated by mesocorticolimbic networks driving pleasure cycles with appetitive, consummatory, and satiation phases. Liking is generated in a small set of discrete hedonic hotspots and coldspots, while wanting is linked to dopamine and to larger distributed brain networks. Breakdown of the pleasure system can lead to anhedonia and other features of affective disorders. (...) Eudaimonia and well-being are difficult to study empirically, yet whole-brain computational models could offer novel insights potentially linking eudaimonia to optimal metastability in the pleasure system. (shrink)

Recent results from neuroimaging appear to indicate that some patients in a vegetative state have partially intact awareness. These results may demonstrate misdiagnosis and suggest the need not only for alternative forms of treatment, but also for the reconsideration of end-of-life decisions in cases of disorders of consciousness. This article addresses the second consequence. First, I will discuss which aspects of consciousness may be involved in neuroimaging findings. I will then consider various factors relevant to ethical end-of-life decision-making, and analyse (...) whether and to what extent the above consequence applies to these factors. It will be shown that knowledge of the existence of partial awareness in patients with disorders of consciousness only influences end-of-life decision-making if certain background assumptions are made. (shrink)

1Neurology Department and Cyclotron Research Center, University of Lie`ge, Sart Tilman B30, 4000 Liege, Belgium 2Neurorehabilitation Medicine, Hoˆpital Caremeau, CHU Nıˆmes, 30029 Nıˆmes Cedex, France 3Department of Speech Therapy, Hospital Pitie´ Salpe´trie`re, Paris and French Association Locked in Syndrome (ALIS), 225 Bd Jean-Jaures, MBE 182, 92100 Boulogne-Billancourt, France 4Neurosciences et Syste`mes Sensoriels Unite´ Mixte de Recherche 5020, Universite´ Claude Bernard Lyon 1 – CNRS, 69007 Lyon, France 5Intensive Care Medicine, Hoˆpital Erasme, Universite´ Libre de Bruxelles, Route de Lennik 808, 1070 (...) Brussels, Belgium 6Anesthesiology, Reanimation and Pain Clinic, CHU University Hospital, Sart Tilman B33, 4000 Liege, Belgium 7German Association Locked in Syndrome LIS e.V., Evangelischen Krankenhaus Ko¨ningin Elisabeth Herzberge gGmbh (Lehrkrankenhaus der Charite´), Haus 30, Herzbergstrasse 79, 10365 Berlin, Germany 8Intensive Care Medicine, Centre Hospitalier Re´gional de la Citadelle, Boulevard du 12e de Ligne 1, 4000 Liege, Belgium 9Biomedical PET Unit, Hoˆpital Erasme, Universite´ Libre de Bruxelles, Route de Lennik 808, 1070 Brussels, Belgium.. (shrink)

BackgroundAssessing consciousness in other subjects, particularly in non-verbal and behaviourally disabled subjects (e.g., patients with disorders of consciousness), is notoriously challenging but increasingly urgent. The high rate of misdiagnosis among disorders of consciousness raises the need for new perspectives in order to inspire new technical and clinical approaches. Main bodyWe take as a starting point a recently introduced list of operational indicators of consciousness that facilitates its recognition in challenging cases like non-human animals and Artificial Intelligence to explore their relevance (...) to disorders of consciousness and their potential ethical impact on the diagnosis and healthcare of relevant patients. Indicators of consciousness mean particular capacities that can be deduced from observing the behaviour or cognitive performance of the subject in question (or from neural correlates of such performance) and that do not define a hard threshold in deciding about the presence of consciousness, but can be used to infer a graded measure based on the consistency amongst the different indicators. The indicators of consciousness under consideration offer a potential useful strategy for identifying and assessing residual consciousness in patients with disorders of consciousness, setting the theoretical stage for an operationalization and quantification of relevant brain activity.ConclusionsOur heuristic analysis supports the conclusion that the application of the identified indicators of consciousness to its disorders will likely inspire new strategies for assessing three very urgent issues: the misdiagnosis of disorders of consciousness; the need for a gold standard in detecting consciousness and diagnosing its disorders; and the need for a refined taxonomy of disorders of consciousness. (shrink)

Recent theoretical advances describing consciousness from information and integration have highlighted the unique role of the thalamocortical system in leading to integrated information and thus, consciousness. Here, we examined the differential distributions of specific and nonspecific thalamocortical functional connections using resting-state fMRI in a group of healthy subjects and vegetative-state patients. We found that both thalamic systems were widely distributed, but they exhibited different patterns. Nonspecific connections were preferentially associated with brain regions involved in higher-order cognitive processing, self-awareness and introspective (...) mentalizing. In contrast, specific connections were prevalent in the ventral and posterior part of the prefrontal and precuneus, known involved in representing externally-directed attentions. Significant reductions of functional connectivity in both systems, especially the nonspecific system, were observed in VS. These data suggest that brain networks sustaining information and integration may be differentiated by the nature of their thalamic functional connectivity. (shrink)

In the care of patients with disorders of consciousness (DOC), some ethical difficulties stem from the challenges of accurate diagnosis and the uncertainty of prognosis. Current neuroimaging research on these disorders could eventually improve the accuracy of diagnoses and prognoses and therefore change the context of end-of-life decision making. However, the perspective of healthcare professionals on these disorders remains poorly understood and may constitute an obstacle to the integration of research. We conducted a qualitative study involving healthcare professionals from an (...) acute care university medical center. A short questionnaire captured demographic data as well as the experience of participants with DOC patients. A semi-structured interview was used to explore attitudes toward ethical issues identified in a previous literature review. Qualitative content analysis of interviews was conducted with the NVivo software. Accurate diagnosis among DOC is often regarded as a challenge, but this was generally not the case for our participants because most reported high confidence in DOC diagnoses. However, participants reported struggling with prognosis, especially because of its essential role for end-of-life decision making and communication with families. Variability of opinion between healthcare professionals was reported and identified by some as a minor issue while others stressed how families struggle with different medical opinions. End-of-life decision making encompassed a large proportion of ethical challenges in these patients, and the removal of artificial nutrition and hydration created significant discomfort in a minority of participants. The concept of futility was subject to wide-ranging understandings with both favorable and unfavorable opinions. Our data suggest that to ensure the incorporation of new evidence-based advances, attention should be directed to the real-world practices and challenges of accurate diagnosis and prognosis. Given pervasive challenges in end-of-life care, we recommend improved training of healthcare professionals in the care of patients with DOC, particularly in end-of life care, understanding the context of decision making, and determining how to optimally integrate new neuroscience research on the care of patients with DOC. (shrink)

Neuroimaging studies of brain-damaged patients diagnosed as in the vegetative state suggest that the patients might be conscious. This might seem to raise no new ethical questions given that in related disputes both sides agree that evidence for consciousness gives strong reason to preserve life. We question this assumption. We clarify the widely held but obscure principle that consciousness is morally significant. It is hard to apply this principle to difficult cases given that philosophers of mind distinguish between a range (...) of notions of consciousness and that is unclear which of these is assumed by the principle. We suggest that the morally relevant notion is that of phenomenal consciousness and then use our analysis to interpret cases of brain damage. We argue that enjoyment of consciousness might actually give stronger moral reasons not to preserve a patient's life and, indeed, that these might be stronger when patients retain significant cognitive function. (shrink)

Our ethical obligations to another being depend at least in part on that being’s capacity for a mental life. Our usual approach to inferring the mental state of another is to reason by analogy: If another being behaves as I do in a circumstance that engenders a certain mental state in me, I conclude that it has engendered the same mental state in him or her. Unfortunately, as philosophers have long noted, this analogy is fallible because behavior and mental states (...) are only contingently related. If the other person is acting, for example, we could draw the wrong conclusion about his or her mental state. In this article I consider another type of analogy that can be drawn between oneself and another to infer the mental state of the other, substituting brain activity for behavior. According to most current views of the mind–body problem, mental states and brain states are non-contingently related, and hence inferences drawn with the new analogy are not susceptible to the alternative interpretations that plague the behavioral analogy. The implications of this approach are explored in two cases for which behavior is particularly unhelpful as a guide to mental status: severely brain–damaged patients who are incapable of intentional communicative behavior, and nonhuman animals whose behavioral repertoires are different from ours and who lack language. (shrink)

Science and philosophy still lack an overarching theory of consciousness. We suggest that a further step toward it requires going beyond the view of the brain as input-output machine and focusing on its intrinsic activity, which may express itself in two distinct modalities, i.e. aware and unaware. We specifically investigate the predisposition of the brain to evaluate and to model the world. These intrinsic activities of the brain retain a deep relation with consciousness. In fact the ability of the brain (...) to evaluate and model the world can develop in two modalities, implicit or explicit, that correspond to what we usually refer to as the unconscious and consciousness, and both are multilevel configurations of the brain along a continuous and dynamic line. Starting from an empirical understanding of the brain as intrinsically active and plastic, we here distinguish between higher cognitive functions and basic phenomenal consciousness, suggesting that the latter might characterize the brain’s intrinsic activity as such, even if at a very basic level. We proceed to explore possible impacts of the notion of intrinsic cerebral phenomenality on our understanding of consciousness and its disorders, particularly on the diagnosis and management of patients with disorders of consciousness. (shrink)

Without exaggeration, it could be said that we are entering a golden age of neuroscience. Informed by recent developments in neuroimaging that allow us to peer into the working brain at both a structural and functional level, neuroscientists are beginning to untangle mechanisms of recovery after brain injury and grapple with age-old questions about brain and mind and their correlates neural mechanisms and consciousness. Neuroimaging, coupled with new diagnostic categories and assessment scales are helping us develop a new diagnostic nosology (...) about disorders of consciousness which will likely improve prognostication and suggest therapeutic advances. Historically such diagnostic refinement has yield therapeutic advances in medicine and there is no reason to doubt that this will be the case for disorders of consciousness, perhaps bringing relief to a marginalized population now on the periphery of the therapeutic agenda. In spite of this promise, the translation of research findings into the clinical context will be difficult. As we move from descriptive categories about disorders of consciousness, like the vegetative or minimally conscious states, to ones further specified by integrating behavioral and neuroimaging findings, humility not hubris should be the virtue that guides the ethical conduct of research and practice. (shrink)

Alba Martínez López y Juan Lupiáñez Castillo Centro de Investigación Mente, Cerebro y Comportamiento, Universidad de Granada, España El diagnóstico … Read More →.

We should eventually understand how exactly first person phenomenal consciousness is generated. When we do, we should be able to enginner one for robots. This is the engineering thesis in machine consciousness.

In this report, we describe the case of a patient who has remained in a comatose state for more than one year after a traumatic and hypoxic brain injury. This state, which we refer to as long-lasting coma (LLC), may be a disorder of consciousness with significantly different features from those of conventional coma, the vegetative state, or brain death. On the basis of clinical, neurophysiological and neuroimaging data, we hypothesize that a multilevel involvement of the ascending reticular activating system (...) is required in LLC. This description may be useful for the identification of other patients suffering from this severe disorder of consciousness, which raises important ethical issues. (shrink)

The clinical and para-clinical examination of residual self-consciousness in non-communicative severely brain damaged patients remains exceptionally challenging. Passive presentation of the patient’s own name and own face are known to be effective attention-grabbing stimuli when clinically assessing consciousness at the patient’s bedside. Event-related potential and functional neuroimaging studies using such self-referential stimuli are currently being used to disentangle the cognitive hierarchy of self-processing. We here review neuropsychological, neuropathological, electrophysiological and neuroimaging studies using the own name and own face paradigm obtained (...) in conscious waking, sleep, pharmacological coma, pathological coma and related disorders of consciousness. Based on these results we discuss what we currently do and do not know about the functional significance of the neural network involved in “automatic” and “conscious” self-referential processing. (shrink)

This paper is a review of the work that has been carried out on machine consciousness. A clear overview of this diverse field is achieved by breaking machine consciousness down into four different areas, which are used to understand its aims, discuss its relationship with other subjects and outline the work that has been carried out so far. The criticisms that have been made against machine consciousness are also covered, along with its potential benefits, and the work that has been (...) done on analysing systems for signs of consciousness. Some of the social and ethical issues raised by machine consciousness are examined at the end of the paper. (shrink)

Over the last few decades, neuroimaging techniques have transformed our understanding of the brain and the effect of neurological conditions on brain function. More recently, light-based modalities such as functional near-infrared spectroscopy have gained popularity as tools to study brain function at the bedside. A recent application is to assess residual awareness in patients with disorders of consciousness, as some patients retain awareness albeit lacking all behavioural response to commands. Functional near-infrared spectroscopy can play a vital role in identifying these (...) patients by assessing command-driven brain activity. The goal of this review is to summarise the studies reported on this topic, to discuss the technical and ethical challenges of working with patients with disorders of consciousness, and to outline promising future directions in this field. (shrink)

There is no controversy in psychology or brain sciences that brains create mind and consciousness. Doubts and opinions to the contrary are quite frequently expressed in non-scientific publications. In particular the idea that conscious mind is received, rather than created by the brain, is quite often used against “materialistic” understanding of consciousness. I summarize here arguments against such position, show that neuroscience gives coherent view of mind and consciousness, and that this view is intrinsically non-materialistic.

Severe brain injury is a leading cause of death and disability. Following severe brain injury diagnosis is difficult and errors frequently occur. Recent findings in clinical neuroscience may offer a solution. Neuroimaging has been used to detect preserved cognitive function and awareness in some patients clinically diagnosed as being in a vegetative state. Remarkably, neuroimaging has also been used to communicate with some vegetative patients through a series of yes/no questions. Some have speculated that, one day, this method may allow (...) severely brain-injured patients to make medical decisions. Yet, skepticism is rife, due in part to the inherent difficulty of assessing decision-making capacity through neuroimaging communication. In this thesis, I provide the first systematic analysis of this problem. I present and defend a strategy for assessing decision-making capacity in brain-injured patients who can only communicate through neuroimaging. (shrink)

To aid neuroscientists in determining the ethical limits of their work and its applications, neuroethical problems need to be identified, catalogued, and analyzed from the standpoint of an ethical framework. Many hospitals have already established either autonomy or welfare-centered theories as their adopted ethical framework. Unfortunately, the choice of an ethical framework resists resolution: each of these two moral theories claims priority at the exclusion of the other, but for patients with neurological pathologies, concerns about the patient’s welfare are treated (...) as meaningless without consideration of the patient’s expressed wishes, and vice versa. Ethicists have long fought over whether suffering or autonomy should be our primary concern, but in neuroethics a resolution of this question is essential to determine the treatment of patients in medical and legal limbo. I propose a solution to this problem in the form of ethical dualism. This is a conservative measure in that it retains both sides of the debate: both happiness and autonomy have intrinsic value. However, this move is often met with resistance because of its more complex nature—it is more difficult to make a decision when there are two parallel sets of values that must be considered than when there is just one such set. The monist theories, though, do not provide enough explanatory power: namely, I will present two recently publicized cases where it is clear that neither ethical value on its own (neither welfare nor autonomy) can fully account for how a vegetative patient should be treated. From the neuroethical cases of Terri Schiavo and Lauren Richardson, I will argue that a dualist framework is superior to its monist predecessors, and I will describe the main features of such an account. (shrink)

JOHANNES ROESSLER & NAOMI EILAN (Eds.)Oxford: Oxford University Press, 2003ISBN 0199245622 (pbk, 415 pages, $39.95)In The Principles of Psychology, William James presents an interesting case of a ‘...

Although most aspects of world and self-consciousness are inherently subjective, neuroscience studies in humans and non-human animals provide correlational and causative indices of specific links between brain activity and representation of the self and the world. In this article we review neuroanatomic, neurophysiological and neuropsychological data supporting the hypothesis that different levels of self and world representation in vertebrates rely upon i) a 'basal' subcortical system that includes brainstem, hypothalamus and central thalamic nuclei and that may underpin the primary (or (...) anoetic) consciousness likely present in all vertebrates; and ii) a forebrain system that include the medial and lateral structures of the cerebral hemispheres and may sustain the most sophisticated forms of consciousness (e.g. noetic (knowledge based) and autonoetic, reflective knowledge). We posit a mutual, bidirectional functional influence between these two major brain circuits. We conclude that basic aspects of consciousness like primary self and core self (based on anoetic and noetic consciousness) are present in many species of vertebrates and that, even self-consciousness (autonoetic consciousness) does not seem to be a prerogative of humans and of some non-human primates but may, to a certain extent, be present in some other mammals and birds. (shrink)

If ever I summon before me my highest ideals of men and medicine, I find them sprung from the spirit of Osler. —Wilder Penfield, M.D. Neuroethics is a recently coined term that is shaping our cultu...

In today’s society, it becomes increasingly important to assess which non-human and non-verbal beings possess consciousness. This review article aims to delineate criteria for consciousness especially in animals, while also taking into account intelligent artifacts. First, we circumscribe what we mean with “consciousness” and describe key features of subjective experience: qualitative richness, situatedness, intentionality and interpretation, integration and the combination of dynamic and stabilizing properties. We argue that consciousness has a biological function, which is to present the subject with a (...) multimodal, situational survey of the surrounding world and body, subserving complex decision-making and goal-directed behavior. This survey reflects the brain’s capacity for internal modeling of external events underlying changes in sensory state. Next, we follow an inside-out approach: how can the features of conscious experience, correlating to mechanisms inside the brain, be logically coupled to externally observable properties? Instead of proposing criteria that would each define a “hard” threshold for consciousness, we outline six indicators: goal-directed behavior and model-based learning; anatomic and physiological substrates for generating integrative multimodal representations; psychometrics and meta-cognition; episodic memory; susceptibility to illusions and multistable perception; and specific visuospatial behaviors. Rather than emphasizing a particular indicator as being decisive, we propose that the consistency amongst these indicators can serve to assess consciousness in particular species. The integration of scores on the various indicators yields an overall, graded criterion for consciousness, somewhat comparable to the Glasgow Coma Scale for unresponsive patients. When considering theoretically derived measures of consciousness, it is argued that their validity should not be assessed on the basis of a single quantifiable measure, but requires cross-examination across multiple pieces of evidence, including the indicators proposed here. Current intelligent machines, including deep learning neural networks and agile robots, are not indicated to be conscious yet. Instead of assessing machine consciousness by a brief Turing-type of test, evidence for it may gradually accumulate when we study machines ethologically and across time, considering multiple behaviors that require flexibility, improvisation, spontaneous problem-solving and the situational conspectus typically associated with conscious experience. (shrink)

Durch den rasanten Fortschritt in den Neurowissenschaften ergibt sich ein bidirektionales Implikationsverhältnis zwischen Ethik und Neurowissenschaften: Einerseits haben neurowissenschaftliche Erkenntnisse epistemische Implikationen für anthropologisch-ethische Grundkonzepte, andererseits haben ethische Kriterien normative Implikationen für neurowissenschaftliche Interventionen. Die Neuroethik untersucht diese normativen Implikationen systematisch auf der metaethischen, der theoretischen und der praktischen Ebene. Um eine spezifische und differenzierte ethische Analyse der einzelnen neurowissenschaftlichen Interventionen zu ermöglichen, soll hier eine bereichsspezifische, neuroethische Kriteriologie vorgestellt werden. Durch exemplarische Anwendung ihrer einzelnen Kriterien auf gegenwärtige und zukünftige (...) neurowissenschaftliche Forschungs- und Interventionsmöglichkeiten soll gezeigt werden, dass sie eine systematische und zugleich praktisch anwendbare Möglichkeit bietet, einen normativen Orientierungsrahmen für Neurowissenschaften und Neurologie zu gewinnen. Insofern sie auf weitgehend konsensfähigen ethischen Prinzipien basiert, kann sie zudem als ethische Grundlage für einen breiten klinischen und wissenschaftlichen Diskurs dienen. (shrink)

Modelling and simulations have gained a leading position in contemporary attempts to describe, explain, and quantitatively predict the human brain's operations. Computer models are highly sophisticated tools developed to achieve an integrated knowledge of the brain with the aim of overcoming the actual fragmentation resulting from different neuroscientific approaches. In this paper we investigate plausibility of simulation technologies for emulation of consciousness and the potential clinical impact of large-scale brain simulation on the assessment and care of disorders of consciousness, e.g. (...) Coma, Vegetative State/Unresponsive Wakefulness Syndrome, Minimally Conscious State.Notwithstanding their technical limitations, we suggest that simulation technologies may offer new solutions to old practical problems, particularly in clinical contexts. We take DOCs as an illustrative case, arguing that the simulation of neural correlates of consciousness is potentially useful for improving treatments of patients with DOCs. (shrink)

Recent theoretical advances describing consciousness from information and integration have highlighted the unique role of the thalamocortical system in leading to integrated information and thus, consciousness. Here, we examined the differential distributions of specific and nonspecific thalamocortical functional connections using resting-state fMRI in a group of healthy subjects and vegetative-state patients. We found that both thalamic systems were widely distributed, but they exhibited different patterns. Nonspecific connections were preferentially associated with brain regions involved in higher-order cognitive processing, self-awareness and introspective (...) mentalizing . In contrast, specific connections were prevalent in the ventral and posterior part of the prefrontal and precuneus, known involved in representing externally-directed attentions. Significant reductions of functional connectivity in both systems, especially the nonspecific system, were observed in VS. These data suggest that brain networks sustaining information and integration may be differentiated by the nature of their thalamic functional connectivity. (shrink)

Objectives: Recent fMRI studies have shown that it is possible to reliably identify the defaultmode network (DMN) in the absence of any task, by resting-state connectivity analyses in healthy volunteers. We here aimed to identify the DMN in the challenging patient population of disorders of consciousness encountered following coma. Experimental design: A spatial independent component analysis-based methodology permitted DMN assessment, decomposing connectivity in all its different sources either neuronal or artifactual. Three different selection criteria were introduced assessing anticorrelation-corrected connectivity with (...) or without an automatic masking procedure and calculating connectivity scores encompassing both spatial and temporal properties. These three methods were validated on 10 healthy controls and applied to an independent group of 8 healthy controls and 11 severely brain-damaged patients [locked-in syndrome (n ¼ 2), minimally conscious (n ¼ 1), and vegetative state (n ¼ 8)]. Principal observations: All vegetative patients showed fewer connections in the default-mode areas, when compared with controls, contrary to locked-in patients who showed nearnormal connectivity. In the minimally conscious-state patient, only the two selection criteria considering both spatial and temporal properties were able to identify an intact right lateralized BOLD connectivity pattern, and metabolic PET data suggested its neuronal origin. Conclusions: When assess-. (shrink)

Neurostimulation to restore cognitive and physical functions is an innovative and promising technique for treating patients with severe brain injury that has resulted in a minimally conscious state (MCS). The technique may involve electrical stimulation of the central thalamus, which has extensive projections to the cerebral cortex. Yet it is unclear whether an improvement in neurological functions would result in a net benefit for these patients. Quality-of-life measurements would be necessary to determine whether any benefit of neurostimulation outweighed any harm (...) in their response to different degrees of cognitive and physical disability. These measures could also indicate whether the technique could be ethically justified and whether surrogates could give proxy consent to its use on brain-injured patients. (shrink)

1 INSERM-CEA Unit 562, Cognitive Neuroimaging, Service Hospitalier Fre´de´ric Joliot, Orsay, France, 2 CNRS URA2182 Re´cepteurs and Cognition, Institut Pasteur, Paris, France.

Neuronal aggregates involved in conscious awareness are not evenly distributed throughout the CNS but comprise key components referred to as the neural network correlates of consciousness (NNCC). A critical node in this network is the posterior cingulate, precuneal, and retrosplenial cortices. The cytological and neurochemical composition of this region is reviewed in relation to the Brodmann map. This region has the highest level of cortical glucose metabolism and cytochrome c oxidase activity. Monkey studies suggest that the anterior thalamic projection likely (...) drives retrosplenial and posterior cingulate cortex metabolism and that the midbrain projection to the anteroventral thalamic nucleus is a key coupling site between the brainstem system for arousal and cortical systems for cognitive processing and awareness. The pivotal role of the posterior cingulate, precuneal, and retrosplenial cortices in consciousness is demonstrated with posterior cingulate epilepsy cases, midcingulate lesions that de-afferent this region and are associated with unilateral sensory neglect, observations from stroke and vegetative state patients, alterations in blood flow during sleep, and the actions of general anesthetics. Since this region is critically involved in self reflection, it is not surprising that it is similarly a site for the NNCC. Interestingly, information processing during complex cognitive tasks and during aversive sensations such as pain induces efforts to terminate self reflection and result in decreased processing in posterior cingulate and precuneal cortices. (shrink)

Name der Zeitschrift: Jahrbuch für Wissenschaft und Ethik Jahrgang: 19 Heft: 1 Seiten: 147-162.

The complex activity of the human brain makes it difficult to get a big picture of how the brain works and functions as the mind. We examine pertinent studies, as well as evolutionary and embryologic evidence to support our theoretical model consisting of separate but interactive layers of human neural activity. The most basic layer involves default mode network (DMN)activity and cardiorespiratory oscillations. We propose that these oscillations support other neural activity and cognitive processes. The second layer involves limbic system (...) activity accompanied by corresponding changes in cardiorespiratory oscillations. The third layer consists of corticothalamic processing and involves higher cortical functions including awareness, cognition,and consciousness. These layers interact to form the complex neural activity of the human brain. Examining the origins and relationships of various neural and physiologic oscillations may provide better understanding of human neurophysiology and consciousness. (shrink)

The application of neuroimaging technology to the study of the injured brain has transformed how neuroscientists understand disorders of consciousness, such as the vegetative and minimally conscious states, and deepened our understanding of mechanisms of recovery. This scientific progress, and its potential clinical translation, provides an opportunity for ethical reflection. It was against this scientific backdrop that we convened a conference of leading investigators in neuroimaging, disorders of consciousness and neuroethics. Our goal was to develop an ethical frame to move (...) these investigative techniques into mature clinical tools. This paper presents the recommendations and analysis of a Working Meeting on Ethics, Neuroimaging and Limited States of Consciousness held at Stanford University during June 2007. It represents an interdisciplinary approach to the challenges posed by the emerging use of neuroimaging technologies to describe and characterize disorders of consciousness. (shrink)

This paper is a review of the work that has been carried out on machine consciousness. A clear overview of this diverse field is achieved by breaking machine consciousness down into four different areas, which are used to understand its aims, discuss its relationship with other subjects and outline the work that has been carried out so far. The criticisms that have been made against machine consciousness are also covered, along with its potential benefits, and the work that has been (...) done on analysing systems for signs of consciousness. Some of the social and ethical issues raised by machine consciousness are examined at the end of the paper. (shrink)

Recent studies indicate that patients who are diagnosed with vegetative states may retain more awareness than their clinical assessments suggest. Disorders of consciousness traditionally have been diagnosed on the basis of outwardly observable behaviors alone, but new functional imaging studies have shown surprising levels of brain activity in some patients, indicating that even higher-level cognitive functions like language processing and visual imagery may be preserved. For example, one recently developed method purports to detect voluntary mental imagery solely on the basis (...) of neural response patterns observed with functional magnetic resonance imaging. This line of research has already led to some widely reported cases of patients who were discovered to have more brain activity than expected. In November 2009, Rom Houben, a Belgian man who was thought to be in a coma for 23 years, was diagnosed with locked-in syndrome through the use of neuroimaging; however, that assessment was later overturned by further testing. (shrink)

The accurate measurement of the level of consciousness of a creature remains a major scientific challenge, nevertheless a number of new accounts that attempt to address this problem have been proposed recently. In this paper we analyze the principles of these new measures of consciousness along with other classical approaches focusing on their applicability to Machine Consciousness (MC). Furthermore, we propose a set of requirements of what we think a suitable measure for MC should be, discussing the associated theoretical and (...) practical issues. Using the proposed requirements as a framework for the design of an integrative measure of consciousness, we explore the possibility of designing such a measure in the context of current state of the art in consciousness studies. (shrink)

The present dissertation starts from the general claim that neuroscience is not neutral, with regard to theoretical questions like the nature of consciousness, but it needs to be complemented with dedicated conceptual analysis. Specifically, the argument for this thesis is that the combination of empirical and conceptual work is a necessary step for assessing the significant questions raised by the most recent study of the brain. Results emerging from neuroscience are conceptually very relevant in themselves but, notwithstanding its theoretical sophistication, (...) neuroscience is not sufficient to provide a complete interpretation or an appropriate understanding of their impact. Consequently, the present thesis starts from the need for an interdisciplinary and hybrid field of research, i.e. fundamental neuroethics. Within this framework, the thesis takes consciousness and related disorders and the addicted brain as illustrative cases of the potential fruitful collaboration between empirical and conceptual investigations. The general goal of the thesis is to contribute to the overall development of bridging the gap between empirical and conceptual understandings of consciousness. The first paper sets the theoretical framework, providing an empirically-based description of the brain with significant philosophical implications for an understanding of consciousness. The last three papers of the thesis try to apply the theoretical framework to illustrative cases. Papers II and III analyse the possible application of science and technology for an easier detection and clinical care of patients with disorders of consciousness, with particular attention to communication mediated by neurotechnology and the simulation of the conscious brain, respectively; paper IV provides a potentially new ethical analysis of addiction within the elaborated general conceptual framework. The conclusion of the thesis is that the impact of neuroscientific results needs that a dedicated conceptual approach reveals and investigates their conceptual meaning. This conceptual analysis is not exclusive but integrative and complementary to the empirical science. The case of consciousness, analysed from both an ethical and conceptual point of view, is highly illustrative in this respect. In the end, a conceptual/linguistic work of clarification is urgently needed. (shrink)