Neurobiology of consciousness: an overview

Investigating functional brain connectivity patterns associated with two hypnotic states

While there's been clinical success and growing research interest in hypnosis, neurobiological underpinnings induced by hypnosis remain unclear. In this fMRI study (which is part of a larger hypnosis project) with 50 hypnosis-experienced participants, we analyzed neural and physiological responses during two hypnosis states, comparing them to non-hypnotic control conditions and to each other. An unbiased whole-brain analysis (multi-voxel- pattern analysis, MVPA), pinpointed key neural hubs in parieto-occipital-temporal areas, cuneal/precuneal and occipital cortices, lingual gyri, and the occipital pole. Comparing directly both hypnotic states revealed depth-dependent connectivity changes, notably in left superior temporal/supramarginal gyri, cuneus, planum temporale, and lingual gyri. Multi-voxel- pattern analysis (MVPA) based seeds were implemented in a seed-to-voxel analysis unveiling region-specific increases and decreases in functional connectivity patterns. Physiologically, the respiration rate significantly slowed during hypnosis. Summarized, these findings foster fresh insights into hypnosis-induced functional connectivity changes and illuminate further knowledge related with the neurobiology of altered consciousness.

Structural changes in brains of patients with disorders of consciousness treated with deep brain stimulation

Disorders of consciousness (DOC) are one of the major consequences after anoxic or traumatic brain injury. So far, several studies have described the regaining of consciousness in DOC patients using deep brain stimulation (DBS). However, these studies often lack detailed data on the structural and functional cerebral changes after such treatment. The aim of this study was to conduct a volumetric analysis of specific cortical and subcortical structures to determine the impact of DBS after functional recovery of DOC patients. Five DOC patients underwent unilateral DBS electrode implantation into the centromedian parafascicular complex of the thalamic intralaminar nuclei. Consciousness recovery was confirmed using the Rappaport Disability Rating and the Coma/Near Coma scale. Brain MRI volumetric measurements were done prior to the procedure, then approximately a year after, and finally 7 years after the implementation of the electrode. The volumetric analysis included changes in regional cortical volumes and thickness, as well as in subcortical structures. Limbic cortices (parahippocampal and cingulate gyrus) and paralimbic cortices (insula) regions showed a significant volume increase and presented a trend of regional cortical thickness increase 1 and 7 years after DBS. The volumes of related subcortical structures, namely the caudate, the hippocampus as well as the amygdala, were significantly increased 1 and 7 years after DBS, while the putamen and nucleus accumbens presented with volume increase. Volume increase after DBS could be a result of direct DBS effects, or a result of functional recovery. Our findings are in accordance with the results of very few human studies connecting DBS and brain volume increase. Which mechanisms are behind the observed brain changes and whether structural changes are caused by consciousness recovery or DBS in patients with DOC is still a matter of debate.

Emotional Awareness and Cognitive Performance in Borderline Intellectual Functioning Young Adolescents

According to DSM-5 and ICD-10, borderline intellectual functioning (BIF) should not be classified properly as a disorder. However, BIF people may present relevant problems of adaptive functioning in several areas of daily activities, and they seem to be more vulnerable to mental diseases. Young adolescence may be considered a particular period for emotional information processing. The "own and others' emotions" awareness can play a crucial role in many daily life situations, such as decision making, interpersonal relationships, and decoding of facial expressions. On this background, a BIF young adolescents group underwent a neuropsychological assessment including emotional and cognitive domains, and was compared with a healthy young adolescents control group (HC). In the overall sample, a significant negative correlation between general intellectual abilities and emotional awareness was found. The BIF group showed a significantly greater level of alexithymia and a poorer performance in higher cognitive tasks than HC group. As hypothesized, a border cognitive functioning influences mentalization processes as ability to discriminate and monitor emotions, as well as higher domains of cognition.

Subliminal (latent) processing of pain and its evolution to conscious awareness

By unconscious or covert processing of pain we refer to nascent interactions that affect the eventual deliverance of pain awareness. Thus, internal processes (viz., repeated nociceptive events, inflammatory kindling, reorganization of brain networks, genetic) or external processes (viz., environment, socioeconomic levels, modulation of epigenetic status) contribute to enhancing or inhibiting the presentation of pain awareness. Here we put forward the notion that for many patients, ongoing sub-conscious changes in brain function are significant players in the eventual manifestation of chronic pain. In this review, we provide clinical examples of nascent or what we term pre-pain processes and the neurobiological mechanisms of how these changes may contribute to pain, but also potential opportunities to define the process for early therapeutic interventions.

Proust's Contribution to the Psychology of Memory

The work of Proust is generally considered to be a major contribution to the psychology of memory. However, there has been no recent evaluation of this contribution from the standpoint of the cognitive sciences. In this article, I examined the scientific status of the reminiscences, this form of retrieval being illustrated by the famous episode of the petite madeleine. It appears that the réminiscences have a place in the taxonomy of the normal memory: they are a form of cued retrieval of explicit memory, characterized by an episodic content where the spatial component of the context is particularly important. Current interpretations in terms of affective or unconscious memory do not seem to be well grounded. The description of the réminiscences cannot be taken at face value for it is subordinate to a philosophy of art which is the main purpose of À la recherche du temps perdu.

There are conscious and unconscious agendas in the brain and both are important-our will can be conscious as well as unconscious

I have been asked to write a few words on consciousness in this editorial issue. My thoughts on consciousness will focus on the relation between consciousness and will. Consciousness is not an epiphenomenon as some people believe-it is not a psychological construct either. Consciousness is a brain function. With deeper thought it is even more than that-a brain state. Writing this, I am in a conscious state, I hope at least. In every day philosophy, a close connection of consciousness with will is ventured, and is expressed in the term "conscious free will". However, this does not mean that our will is totally determined and not free, be it conscious or unconscious. Total determinists postulate total freedom from nature in order to speak of free will. Absolute freedom from nature is an a priori impossibility; there is no way to escape from nature. However, we have relative freedom, graded freedom, freedom in degrees, enabling us to make responsible decisions and be captains of our own destiny. We are not totally determined. We can upregulate our degrees of freedom by self-management or we can downregulate them by self-mismanagement. In the present communication consciousness and the unconscious are discussed in their various aspects and interactions.

Meditation states and traits: EEG, ERP, and neuroimaging studies

Neuroelectric and imaging studies of meditation are reviewed. Electroencephalographic measures indicate an overall slowing subsequent to meditation, with theta and alpha activation related to proficiency of practice. Sensory evoked potential assessment of concentrative meditation yields amplitude and latency changes for some components and practices. Cognitive event-related potential evaluation of meditation implies that practice changes attentional allocation. Neuroimaging studies indicate increased regional cerebral blood flow measures during meditation. Taken together, meditation appears to reflect changes in anterior cingulate cortex and dorsolateral prefrontal areas. Neurophysiological meditative state and trait effects are variable but are beginning to demonstrate consistent outcomes for research and clinical applications. Psychological and clinical effects of meditation are summarized, integrated, and discussed with respect to neuroimaging data.

Consciousness, epilepsy, and emotional qualia

The last decade has seen a renaissance of consciousness studies, witnessed by the growing number of scientific investigations on this topic. The concept of consciousness is central in epileptology, despite the methodological difficulties concerning its application to the multifaced ictal phenomenology. The authors provide an up-to-date review of the neurological literature on the relationship between epilepsy and consciousness and propose a bidimensional model (level vs contents of consciousness) for the description of seizure-induced alterations of conscious states, according to the findings of recent neuroimaging studies. The neurophysiological correlates of ictal loss and impairment of consciousness are also reviewed. Special attention is paid to the subjective experiential states associated with medial temporal lobe epilepsy. Such ictal phenomenal experiences are suggested as a paradigm for a neuroscientific approach to the apparently elusive philosophical concept of qualia. Epilepsy is confirmed to represent a privileged window over basic neurobiological mechanisms of consciousness.

The emergence of a shared action ontology: Building blocks for a theory

To have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting our world, possesses an ontology too. It creates primitives and makes existence assumptions. It decomposes target space in a way that exhibits a certain invariance, which in turn is functionally significant. We will investigate which are the functional regularities guiding this decomposition process, by answering to the following questions: What are the explicit and implicit assumptions about the structure of reality, which at the same time shape the causal profile of the brain's motor output and its representational deep structure, in particular of the conscious mind arising from it (its "phenomenal output")? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results and integrating them with a wider philosophical perspective, we will emphasize the contribution the motor system makes to this process. As it will be shown, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence demonstrates that the brain models movements and action goals in terms of multimodal representations of organism-object-relations. Under a representationalist analysis, this process can be conceived of as an internal, dynamic representation of the intentionality-relation itself. We will show how such a complex form of representational content, once it is in place, can later function as a functional building block for social cognition and for a more complex, consciously experienced representation of the first-person perspective as well.

Runner-up in the young physician's section of the Gowers' prize 2000. Epilepsy and the physical basis of consciousness

The issue of human consciousness, in both its popular and neuroscientific sense, is considered from a clinical perspective. The ictal semiologies of the various epilepsies, together with associated clinical features, are demonstrated to highlight certain neuroanatomical and neurophysiological facets of consciousness. It is suggested that further insights into consciousness, even those bordering on the philosophical, may be led by clinical neurological phenomena and emerging neuroinvestigative techniques.

Cognitive-processing bias in chronic pain: a review and integration

Do patients with chronic pain selectively process pain- and illness-related stimuli? The evidence with regard to attention, interpretation, and recall biases is critically reviewed. A model is proposed to account for the findings in which it is suggested that biases in information processing in chronic pain are the result of overlap between 3 schemas: pain, illness, and self. With frequent repeated or continued experience of pain, the pain schema becomes enmeshed with illness and self-schemas. The extent of the enmeshment and the salient content of the schema determine the bias. A fundamental assumption is that all patients with pain selectively process sensory-intensity information. A clinical implication of the results is that processing biases that extend beyond this healthy and adaptive process to enmesh the self-schema with pain and illness schemas could maintain and exacerbate distress and illness behavior in patients with chronic pain.

Temporal binding and the neural correlates of sensory awareness

Theories of binding have recently come into the focus of the consciousness debate. In this review, we discuss the potential relevance of temporal binding mechanisms for sensory awareness. Specifically, we suggest that neural synchrony with a precision in the millisecond range may be crucial for conscious processing, and may be involved in arousal, perceptual integration, attentional selection and working memory. Recent evidence from both animal and human studies demonstrates that specific changes in neuronal synchrony occur during all of these processes and that they are distinguished by the emergence of fast oscillations with frequencies in the gamma-range.