Pierre Maquet1,2,6, Steven Laureys1,2, Philippe Peigneux1,2,3, Sonia Fuchs1, Christophe Petiau1, Christophe Phillips1,6, Joel Aerts1, Guy Del Fiore1, Christian Degueldre1, Thierry Meulemans3, André Luxen1, Georges Franck1,2, Martial Van Der Linden3, Carlyle Smith4 and Axel Cleeremans5.

In cognitive neuroscience, dissociating the brain networks that ing—has thus become one of the best empirical situations subtend conscious and nonconscious memories constitutes a through which to study the mechanisms of implicit learning, very complex issue, both conceptually and methodologically.

Using positron emission tomography (PET) and regional cerebral blood flow (rCBF) measurements, we investigated the cerebral correlates of consciousness in a sequence learning task through a novel application of the Process Dissociation Procedure, a behavioral paradigm that makes it possible to separately assess conscious and unconscious contributions to performance. Results show that the metabolic response in the anterior cingulate / mesial prefrontal cortex (ACC / MPFC) is exclusively and specifically correlated with the explicit component of performance during recollection of a (...) learned sequence. This suggests a significant role for the ACC / MPFC in the explicit processing of sequential material.  2003 Elsevier Science B.V. All rights reserved. (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)

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)

Soltis' paper contains little data on the underlying neural substrate of the discussed signal function of early infant crying – probably because there is amazingly little known about it. We here discuss the interest of functional neuroimaging as an objective measurement of brain activity in (1) early infants during crying and (2) parents hearing their offspring cry.

Patient To examine neural responses to aurally-presented sentences, a sparse imaging technique was used to minimize interference from scanner noise. The patient was played a single sentence (or noise-equivalent) in the 7.4s silent period before a single 1.6s scan with stimulus timing jittered relative to scan onset. There were 118 spoken sentences trials, 59 signal correlated noise trials, and an additional 60 silent trials for the purpose of monitoring data quality. The signal correlated noise stimuli had the same duration, spectral (...) profile and amplitude envelope as the original speech, but were entirely unintelligible (S1). The experiment was divided into three sessions of 79 trials with events pseudo-randomly ordered within each scanning session. The sentences were presented using a MRI compatible auditory stimulusdelivery system (Resonance Technology, Northridge, CA), with insert earplugs to further attenuate scanner noise. DMDX software running on a Windows XP PC was used to present the stimulus items. (shrink)

Consciousness is one of the most significant scientific problems today. Renewed interest in the nature of consciousness - a phenomenon long considered not to be scientifically explorable, as well as increasingly widespread availability of multimodal functional brain imaging techniques (EEG, ERP, MEG, fMRI and PET), now offer the possibility of detailed, integrated exploration of the neural, behavioral, and computational correlates of consciousness. The present volume aims to confront the latest theoretical insights in the scientific study of human consciousness with the (...) most recent behavioral, neuroimaging, electrophysiological, pharmacological and neuropathological data on brain function in altered states of consciousness such as: brain death, coma, vegetative state, minimally conscious state, locked-in syndrome, dementia, epilepsy, schizophrenia, hysteria, general anesthesia, sleep, hypnosis, and hallucinations. The interest of this is threefold. First, patients with altered states of consciousness continue to represent a major clinical problem in terms of clinical assessment of consciousness and daily management. Second, the exploration of brain function in altered states of consciousness represents a unique lesional approach to the scientific study of consciousness and adds to the worldwide effort to identify the "neural correlate of consciousness". Third, new scientific insights in this field have major ethical and social implications regarding our care for these patients. (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)

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)

Sleep has long been a topic of fascination for artists and scientists. Why do we sleep? What function does sleep serve? Why do we dream? What significance can we attach to our dreams? We spend so much of our lives sleeping, yet its precise function is unclear, in spite of our increasing understanding of the processes generating and maintaining sleep. We now know that sleep can be accompanied by periods of intense cerebral activity, yet only recently has experimental data started (...) to provide us with some insights into the type of processing taking place in the brain as we sleep. There is now strong evidence that sleep plays a crucial role in learning and in the consolidation of memories. Once the preserve of psychoanalysts, 'dreaming' is now a topic of increasing interest amongst scientists. With research into sleep growing, this volume is both timely and valuable in presenting a unique study of the relationship between sleep, learning, and memory. It brings together a team of international scientists researching sleep in both human and animal subjects. Aimed at researchers within the fields of neuroscience, cognitive neuroscience, psychiatry, and neurology, this book will be an important first step in developing a full scientific understanding of the most intriguing state of consciousness. (shrink)

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

Conscious perception, like the sight of a coffee cup, seems to involve the brain identifying a stimulus. But conscious input activates more brain regions than are needed to identify coffee cups and faces. It spreads beyond sensory cortex to frontoparietal association areas, which do not serve stimulus identification as such. What is the role of those regions? Parietal cortex support the ‘first person perspective’ on the visual world, unconsciously framing the visual object stream. Some prefrontal areas select and interpret conscious (...) events for executive control. Such functions can be viewed as properties of the subject, rather than the object, of experience – the ‘observing self’ that appears to be needed to maintain the conscious state. (shrink)

Niedenthal et al. discuss the importance of eye gaze in embodied simulation and, more globally, in the processing of emotional visual stimulation (such as facial expression). In this commentary, we illustrate the relationship between oriented eye movements, consciousness, and emotion by using the case of severely brain-injured patients recovering from coma (i.e., vegetative and minimally conscious patients).

Background: Spasticity following a stroke occurs in about 30% of patients. The mechanisms underlying this disorder, however, are not well understood. Method: This review aims to define spasticity, describe hypotheses explaining its development after a stroke, give an overview of related neuroimaging studies as well as a description of the most common scales used to quantify the degree of spasticity and finally explore which treatments are currently being used to treat this disorder.

Brain damage can cause massive changes in consciousness levels. From a clinical and ethical point of view it is desirable to assess the level of residual consciousness in unresponsive patients. However, no direct measure of consciousness exists, so we run into the philosophical problem of other minds. Neurologists often make implicit use of a Turing test-like procedure in an attempt to gain access to damaged minds, by monitoring and interpreting neurobehavioral responses. New brain imaging techniques are now being developed that (...) permit communication with unresponsive patients, using their brain signals as carriers of messages relating to their mental states. (shrink)

Understanding loss of consciousness after brain injury poses a practical test for the field of consciousness research, with both clinical and ethical implications. We here discuss three major pathological disorders of consciousness; coma, the unresponsive wakefulness syndrome and the minimally conscious state, which together represent a lesion model for the investigation of human awareness. We review the anatomical and neurophysiological correlates of each condition, and discuss the current findings in context of several theoretical frameworks of consciousness.

Pain, suffering and positive emotions in patients in vegetative state/unresponsive wakefulness syndrome (VS/uws) and minimally conscious states (MCS) pose clinical and ethical challenges. Clinically, we evaluate behavioural responses after painful stimulation and also emotionally-contingent behaviours (e.g., smiling). Using stimuli with emotional valence, neuroimaging and electrophysiology technologies can detect subclinical remnants of preserved capacities for pain which might influence decisions about treatment limitation. To date, no data exist as to how healthcare providers think about end-of-life options (e.g., withdrawal of artificial nutrition (...) and hydration) in the presence or absence of pain in non-communicative patients. Here, we aimed to better clarify this issue by re-analyzing previously published data on pain perception (Prog Brain Res 2009 177, 329–38) and end-of-life decisions (J Neurol 2010 258, 1058–65) in patients with disorders of consciousness. In a sample of 2259 European healthcare professionals we found that, for VS/uws more respondents agreed with treatment withdrawal when they considered that VS/uws patients did not feel pain (77%) as compared to those who thought VS/uws did feel pain (59%). This interaction was influenced by religiosity and professional background. For MCS, end-of-life attitudes were not influenced by opinions on pain perception. Within a contemporary ethical context we discuss (1) the evolving scientific understandings of pain perception and their relationship to existing clinical and ethical guidelines; (2) the discrepancies of attitudes within (and between) healthcare providers and their consequences for treatment approaches, and (3) the implicit but complex relationship between pain perception and attitudes toward life-sustaining treatments. (shrink)

Different sort of people are interested in personal identity. Philosophers frequently ask what it takes to remain oneself. Caregivers imagine their patients’ experience. But both philosophers and caregivers think from the armchair: they can only make assumptions about what it would be like to wake up with massive bodily changes. Patients with a locked-in syndrome suffer a full body paralysis without cognitive impairment. They can tell us what it is like. Forty-four chronic LIS patients and 20 age-matched healthy medical professionals (...) answered a 15-items questionnaire targeting: global evaluation of identity, body representation and experienced meaning in life. In patients, self-reported identity was correlated with B and C. Patients differed with controls in C. These results suggest that the paralyzed body remains a strong component of patients’ experienced identity, that patients can adjust to objectives changes perceived as meaningful and that caregivers fail in predicting patients’ experience. (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)