Dynamic Change of Global and Local Information Processing in Propofol-Induced Loss and Recovery of Consciousness

Whether unique to humans or not, consciousness is a central aspect of our experience of the world. The neural fingerprint of this experience, however, remains one of the least understood aspects of the human brain. In this paper we employ graph-theoretic measures and support vector machine classification to assess, in 12 healthy volunteers, the dynamic reconfiguration of functional connectivity during wakefulness, propofol-induced sedation and loss of consciousness, and the recovery of wakefulness. Our main findings, based on resting-state fMRI, are three-fold. First, we find that propofol-induced anesthesia does not bear differently on long-range versus short-range connections. Second, our multi-stage design dissociated an initial phase of thalamo-cortical and cortico-cortical hyperconnectivity, present during sedation, from a phase of cortico-cortical hypoconnectivity, apparent during loss of consciousness. Finally, we show that while clustering is increased during loss of consciousness, as recently suggested, it also remains significantly elevated during wakefulness recovery. Conversely, the characteristic path length of brain networks (i.e., the average functional distance between any two regions of the brain) appears significantly increased only during loss of consciousness, marking a decrease of global information-processing efficiency uniquely associated with unconsciousness. These findings suggest that propofol-induced loss of consciousness is mainly tied to cortico-cortical and not thalamo-cortical mechanisms, and that decreased efficiency of information flow is the main feature differentiating the conscious from the unconscious brain.     

Celebrating and Advocating the Personalisation of the World: A Reply to Don Gardner

In replying to a critique of my book Transcendent Individual: Towards a Literary and Liberal Anthropology (TAJA 2000, 11(1):59–77), I argue in this piece that a genuinely nuanced appreciation of the tension between the culturo‐symbolic forms of social life on the one hand and, on the other, the individual energies which animate the forms and afford them purpose and content, means more than merely paying lip service (á la Giddens or Bourdieu) to a notion of agency. The individual can be seen to be more than a conduit by which impersonal social structures reproduce in time. Indeed, it is the ‘personalisation of the world’—the way in which the individual makes environments personal to him or her (in terms of what they are and what they mean)—which provides social life with its logic(s), character(s) and cause(s). What is called for is an aesthetic appreciation both of the way individual consciousness works and of the way this is best represented in literary‐cum‐poetic forms. Placing the conscious individual at the centre of social theory is, however, an ethical and pedagogic matter as well as a methodological one. Celebrating the personalisation of the world is a route not only to understanding human interaction in socio‐cultural milieux but also to advocating liberal milieux where the human remains sovereign.     

A Method for Investigating Age-related Differences in the Functional Connectivity of Cognitive Control Networks Associated with Dimensional Change Card Sort Performance

The ability to adjust behavior to sudden changes in the environment develops gradually in childhood and adolescence. For example, in the Dimensional Change Card Sort task, participants switch from sorting cards one way, such as shape, to sorting them a different way, such as color. Adjusting behavior in this way exacts a small performance cost, or switch cost, such that responses are typically slower and more error-prone on switch trials in which the sorting rule changes as compared to repeat trials in which the sorting rule remains the same. The ability to flexibly adjust behavior is often said to develop gradually, in part because behavioral costs such as switch costs typically decrease with increasing age. Why aspects of higher-order cognition, such as behavioral flexibility, develop so gradually remains an open question. One hypothesis is that these changes occur in association with functional changes in broad-scale cognitive control networks. On this view, complex mental operations, such as switching, involve rapid interactions between several distributed brain regions, including those that update and maintain task rules, re-orient attention, and select behaviors. With development, functional connections between these regions strengthen, leading to faster and more efficient switching operations. The current video describes a method of testing this hypothesis through the collection and multivariate analysis of fMRI data from participants of different ages.     

Fish can show emotional fever: stress-induced hyperthermia in zebrafish

Whether fishes are sentient beings remains an unresolved and controversial question. Among characteristics thought to reflect a low level of sentience in fishes is an inability to show stress-induced hyperthermia (SIH), a transient rise in body temperature shown in response to a variety of stressors. This is a real fever response, so is often referred to as ‘emotional fever’. It has been suggested that the capacity for emotional fever evolved only in amniotes (mammals, birds and reptiles), in association with the evolution of consciousness in these groups. According to this view, lack of emotional fever in fishes reflects a lack of consciousness. We report here on a study in which six zebrafish groups with access to a temperature gradient were either left as undisturbed controls or subjected to a short period of confinement. The results were striking: compared to controls, stressed zebrafish spent significantly more time at higher temperatures, achieving an estimated rise in body temperature of about 2–4°C. Thus, zebrafish clearly have the capacity to show emotional fever. While the link between emotion and consciousness is still debated, this finding removes a key argument for lack of consciousness in fishes.     

Characterization of Phase Transition in the Thalamocortical System during Anesthesia-Induced Loss of Consciousness

The thalamocortical system plays a key role in the breakdown or emergence of consciousness, providing bottom-up information delivery from sensory afferents and integrating top-down intracortical and thalamocortical reciprocal signaling. A fundamental and so far unanswered question for cognitive neuroscience remains whether the thalamocortical switch for consciousness works in a discontinuous manner or not. To unveil the nature of thalamocortical system phase transition in conjunction with consciousness transition, ketamine/xylazine was administered unobtrusively to ten mice under a forced working test with motion tracker, and field potentials in the sensory and motor-related cortex and thalamic nuclei were concomitantly collected. Sensory and motor-related thalamocortical networks were found to behave continuously at anesthesia induction and emergence, as evidenced by a sigmoidal response function with respect to anesthetic concentration. Hyperpolarizing and depolarizing susceptibility diverged, and a non-discrete change of transitional probability occurred at transitional regimes, which are hallmarks of continuous phase transition. The hyperpolarization curve as a function of anesthetic concentration demonstrated a hysteresis loop, with a significantly higher anesthetic level for transition to the down state compared to transition to the up state. Together, our findings concerning the nature of phase transition in the thalamocortical system during consciousness transition further elucidate the underlying basis for the ambiguous borderlines between conscious and unconscious brains. Moreover, our novel analysis method can be applied to systematic and quantitative handling of subjective concepts in cognitive neuroscience.     

Directional Connectivity between Frontal and Posterior Brain Regions Is Altered with Increasing Concentrations of Propofol

Recent studies using electroencephalography (EEG) suggest that alteration of coherent activity between the anterior and posterior brain regions might be used as a neurophysiologic correlate of anesthetic-induced unconsciousness. One way to assess causal relationships between brain regions is given by renormalized partial directed coherence (rPDC). Importantly, directional connectivity is evaluated in the frequency domain by taking into account the whole multichannel EEG, as opposed to time domain or two channel approaches. rPDC was applied here in order to investigate propofol induced changes in causal connectivity between four states of consciousness: awake (AWA), deep sedation (SED), loss (LOC) and return of consciousness (ROC) by gathering full 10/20 system human EEG data in ten healthy male subjects. The target-controlled drug infusion was started at low rate with subsequent gradual stepwise increases at 10 min intervals in order to carefully approach LOC (defined as loss of motor responsiveness to a verbal stimulus). The direction of the causal EEG-network connections clearly changed from AWA to SED and LOC. Propofol induced a decrease (p = 0.002–0.004) in occipital-to-frontal rPDC of 8-16 Hz EEG activity and an increase (p = 0.001–0.040) in frontal-to-occipital rPDC of 10–20 Hz activity on both sides of the brain during SED and LOC. In addition, frontal-to-parietal rPDC within 1–12 Hz increased in the left hemisphere at LOC compared to AWA (p = 0.003). However, no significant changes were detected between the SED and the LOC states. The observed decrease in back-to-front EEG connectivity appears compatible with impaired information flow from the posterior sensory and association cortices to the executive prefrontal areas, possibly related to decreased ability to perceive the surrounding world during sedation. The observed increase in the opposite (front-to-back) connectivity suggests a propofol concentration dependent association and is not directly related to the level of consciousness per se.     

Research on the relation of EEG signal chaos characteristics with high-level intelligence activity of human brain

Using phase space reconstruct technique from one-dimensional and multi-dimensional time series and the quantitative criterion rule of system chaos, and combining the neural network; analyses, computations and sort are conducted on electroencephalogram (EEG) signals of five kinds of human consciousness activities (relaxation, mental arithmetic of multiplication, mental composition of a letter, visualizing a 3-dimensional object being revolved about an axis, and visualizing numbers being written or erased on a blackboard). Through comparative studies on the determinacy, the phase graph, the power spectra, the approximate entropy, the correlation dimension and the Lyapunov exponent of EEG signals of 5 kinds of consciousness activities, the following conclusions are shown: (1) The statistic results of the deterministic computation indicate that chaos characteristic may lie in human consciousness activities, and central tendency measure (CTM) is consistent with phase graph, so it can be used as a division way of EEG attractor. (2) The analyses of power spectra show that ideology of single subject is almost identical but the frequency channels of different consciousness activities have slight difference. (3) The approximate entropy between different subjects exist discrepancy. Under the same conditions, the larger the approximate entropy of subject is, the better the subject's innovation is. (4) The results of the correlation dimension and the Lyapunov exponent indicate that activities of human brain exist in attractors with fractional dimensions. (5) Nonlinear quantitative criterion rule, which unites the neural network, can classify different kinds of consciousness activities well. In this paper, the results of classification indicate that the consciousness activity of arithmetic has better differentiation degree than that of abstract.     

Reduction in inter-hemispheric connectivity in disorders of consciousness

Clinical diagnosis of disorders of consciousness (DOC) caused by brain injury poses great challenges since patients are often behaviorally unresponsive. A promising new approach towards objective DOC diagnosis may be offered by the analysis of ultra-slow (<0.1 Hz) spontaneous brain activity fluctuations measured with functional magnetic resonance imaging (fMRI) during the resting-state. Previous work has shown reduced functional connectivity within the "default network", a subset of regions known to be deactivated during engaging tasks, which correlated with the degree of consciousness impairment. However, it remains unclear whether the breakdown of connectivity is restricted to the "default network", and to what degree changes in functional connectivity can be observed at the single subject level. Here, we analyzed resting-state inter-hemispheric connectivity in three homotopic regions of interest, which could reliably be identified based on distinct anatomical landmarks, and were part of the "Extrinsic" (externally oriented, task positive) network (pre- and postcentral gyrus, and intraparietal sulcus). Resting-state fMRI data were acquired for a group of 11 healthy subjects and 8 DOC patients. At the group level, our results indicate decreased inter-hemispheric functional connectivity in subjects with impaired awareness as compared to subjects with intact awareness. Individual connectivity scores significantly correlated with the degree of consciousness. Furthermore, a single-case statistic indicated a significant deviation from the healthy sample in 5/8 patients. Importantly, of the three patients whose connectivity indices were comparable to the healthy sample, one was diagnosed as locked-in. Taken together, our results further highlight the clinical potential of resting-state connectivity analysis and might guide the way towards a connectivity measure complementing existing DOC diagnosis.     

Quantum monadology: a consistent world model for consciousness and physics

The NL world model presented in the previous paper is embodied by use of relativistic quantum mechanics, which reveals the significance of the reduction of quantum states and the relativity principle, and locates consciousness and the concept of flowing time consistently in physics. This model provides a consistent framework to solve apparent incompatibilities between consciousness (as our interior experience) and matter (as described by quantum mechanics and relativity theory). Does matter have an inside? What is the flowing time now? Does physics allow the indeterminism by volition? The problem of quantum measurement is also resolved in this model.     

Class consciousness and political action in Testour

Conclusion I began this article with an effort to see how the concept of consciousness could be operationalized within an anthropological framework. It is clear from the examination of the concept that to use it to label or to judge is misleading. Instead, consciousness must be dialectical to be meaningful. Political, social or class consciousness emerges from a heritage of culture and a particular social context; it forms an understanding of society and so it shapes action. The presumption is that a particular action is reflective of some kind of an understanding, some kind of awareness. Further, the pattern of action is in turn a prime determinant of the consciousness of the actors.Thus we can observe several different types of social situation from the point of view of determining whether politics is based on a consciousness of class: (1) where class is not a basis for action; (2) where class is a basis for action but the understanding of that situation by actors is in terms of another code, one furnished by religion or by a sense of corporatism, so that the class basis for action is disguised; (3) where class is the basis for social action, and is perceived as such. The difference between these last two cases is the gap that Marx referred to in his analysis of the fetishism of commidities, or that caused Lukacs to distinguish between consciousness and false consciousness. If the people act as though class were a consideration (whether or not they call it class) in situations which divide people along class lines, then a consciousness of class will probably emerge if it is not present already. Our interest here should not be in the individual but in the accepted definition of the situation, the code or the metaphor.I have attempted to extrapolate from the actions of politics to some hypotheses about consciousness. My conclusion is that the evidence for class consciousness is more indirect than direct. In the case of the zerda, consciousness of class is not reinforced, though there are elements of class organization present. The election is similar to the zerda in that interpersonal rivalry is important, but different in that it is explicitly political, and the State appears on the scene. The reaction to the flood also highlights relations between Testouris and the State, but there is also a new element in the form of a fairly open confrontation between two classes. While it would be difficult to impute class consciousness except in the last case, the presence of class relations suggests that the Testouri model of society may soon develop such a perception.One source of awareness of class is the relations of production within Testour's agrarian society. Many of the institutions of the town mask the full impact of these relations: the emphasis placed on interpersonal rivalry, the stress on genealogical and geographical origin, and the strong sense of being from the town. Nevertheless, an awareness of class sometimes complements a behavior determined along class lines, as in the reaction to the flood. A second source of class consciousness would be the power relations that exist between the State, as the instrument of the dominant class at the national level, and the various segments of Tunisian society. People are conscious of these as political relations rather than the political expression of class relations, and so here, too, some aspects of the social relationship are not recognized.The partially negative conclusion concerning class consciousness reflects the stage in the transition from precapitalist to capitalist society that Testour has reached. The complexity and subtlety of the real case should be a corrective to overhasty generalization as well as a contribution to the growing debate on the usefulness of consciousness as a concept in anthropology. As Lynch argues, it is one way to restore the problematic of meaning to a mechanistic interpretation of a particular social situation. The idea of consciousness provides a sense of movement in change and creates the possibility of a dialectical understanding of political action.Nicholas Hopkins is Chair of the Department of Anthropology, Sociology and Psychology at the American University in Cairo.

---

     

Gratuitousness: Notes Towards an Anthropology of Interiority

Interiority—an individual's inner consciousness, the continual conversation one has with oneself–remains an anthropological terra incognita. Literature has been less circumspect in this regard; fiction might be said to be ‘truer’ than social science in its efforts and intent to deal with how individual consciousness feels in the everyday and is immanent in social life. In this article I argue for recognising interiority as a crucial focus of anthropological endeavour, and I outline a possible way in which interiority might be evidenced as irrupting onto the social scene. Interiority makes its paradoxical appearance in social settings in the form of a strangeness, an individual purity and integrity, for which the term ‘gratuitousness’ is apposite. The language of individuals' interior conversation is routinely contained within the language of public exchange; on occasion it bursts these bounds. In both cases, I contend, interior conversation is an existential norm, which holds a key to understanding social life. The course of the article is to review, briefly but critically, disciplinary tendencies which have rendered individual interiority an impossible or irrelevant anthropological theme. A method of interiority is then outlined by way of an anthropological reading of two literary texts. The article ends by reconsidering the potential of an anthropology project that has a concern for interiority. The modern discovery of inner experience, of a realm of purely personal events that are always at the individual's command, and that are his exclusively as well as inexpensively for refuge, consolation and thrill is also a great and liberating discovery. It implies a new worth and sense of dignity in human individuality.     

Qualia: The Geometry of Integrated Information

According to the integrated information theory, the quantity of consciousness is the amount of integrated information generated by a complex of elements, and the quality of experience is specified by the informational relationships it generates. This paper outlines a framework for characterizing the informational relationships generated by such systems. Qualia space (Q) is a space having an axis for each possible state (activity pattern) of a complex. Within Q, each submechanism specifies a point corresponding to a repertoire of system states. Arrows between repertoires in Q define informational relationships. Together, these arrows specify a quale—a shape that completely and univocally characterizes the quality of a conscious experience. Φ— the height of this shape—is the quantity of consciousness associated with the experience. Entanglement measures how irreducible informational relationships are to their component relationships, specifying concepts and modes. Several corollaries follow from these premises. The quale is determined by both the mechanism and state of the system. Thus, two different systems having identical activity patterns may generate different qualia. Conversely, the same quale may be generated by two systems that differ in both activity and connectivity. Both active and inactive elements specify a quale, but elements that are inactivated do not. Also, the activation of an element affects experience by changing the shape of the quale. The subdivision of experience into modalities and submodalities corresponds to subshapes in Q. In principle, different aspects of experience may be classified as different shapes in Q, and the similarity between experiences reduces to similarities between shapes. Finally, specific qualities, such as the “redness” of red, while generated by a local mechanism, cannot be reduced to it, but require considering the entire quale. Ultimately, the present framework may offer a principled way for translating qualitative properties of experience into mathematics.     

Twice-Born, Once Conceived: Meaning Construction and Cultural Cognition

Cultural cognition is the product of two different sorts of meaning: (a) the (objective) semiotic organization of cultural texts or models, and (b) the (subjective) processes of meaning construction through which cultural symbols become available to consciousness as "experience." This article proposes a way to bridge these two kinds of meaning by considering how cultural knowledge is grounded in sensory experience. Several cognitive processes (schematization, synesthesia, secondary intersubjectivity) are proposed for linking the objectively available schemata found in cultural practices and the processes of meaning construction by which individuals appropriate symbols to consciousness. The nature of the relation between public symbols and individual experience is discussed in relation to a number of current issues in post-structuralist culture theory.     

Individual Differences in Personality Predict How People Look at Faces

Background

Determining the ways in which personality traits interact with contextual determinants to shape social behavior remains an important area of empirical investigation. The specific personality trait of neuroticism has been related to characteristic negative emotionality and associated with heightened attention to negative, emotionally arousing environmental signals. However, the mechanisms by which this personality trait may shape social behavior remain largely unspecified.

Methodology/Principal Findings

We employed eye tracking to investigate the relationship between characteristics of visual scanpaths in response to emotional facial expressions and individual differences in personality. We discovered that the amount of time spent looking at the eyes of fearful faces was positively related to neuroticism.

Conclusions/Significance

This finding is discussed in relation to previous behavioral research relating personality to selective attention for trait-congruent emotional information, neuroimaging studies relating differences in personality to amygdala reactivity to socially relevant stimuli, and genetic studies suggesting linkages between the serotonin transporter gene and neuroticism. We conclude that personality may be related to interpersonal interaction by shaping aspects of social cognition as basic as eye contact. In this way, eye gaze represents a possible behavioral link in a complex relationship between genes, brain function, and personality.     

Challenges and opportunities for biogeography—What can we still learn from von Humboldt?

Alexander von Humboldt was arguably the most influential scientist of his day. Although his fame has since lessened relative to some of his contemporaries, we argue that his influence remains strong—mainly because his approach to science inspired others and was instrumental in furthering other scientific disciplines (such as evolution, through Darwin, and conservation science, through Muir)—and that he changed the way that large areas of science are done and communicated. Indeed, he has been called the father of a range of fields, including environmental science, earth system science, plant geography, ecology and conservation. His approach was characterized by making connections between non‐living and living nature (including humans), based on interdisciplinary thinking and informed by large amounts of data from systematic, accurate measurements in a geographical framework. Although his approach largely lacked an evolutionary perspective, he was fundamental to creating the circumstances for Darwin and Wallace to advance evolutionary science. He devoted considerable effort illustrating, communicating and popularizing science, centred on the excitement of pure science. In biogeography, his influence remains strong, including in relating climate to species distributions (e.g. biomes and latitudinal and elevational gradients) and in the use of remote sensing and species distribution modelling in macroecology. However, some key aspects of his approach have faded, particularly as science fragmented into specific disciplines and became more reductionist. We argue that asking questions in a more Humboldtian way is important for addressing current global challenges. This is well‐exemplified by researching links between geodiversity and biodiversity. Progress on this can be made by (a) systematic data collection to improve our knowledge of biodiversity and geodiversity around the world; (b) improving our understanding of the linkages between biodiversity and geodiversity; and (c) developing our understanding of the interactions of geological, biological, ecological, environmental and evolutionary processes in biogeography.     

The Problem of the "Formative" Elements of Consciousness in the Activity Theory of the Mind

The problem of the structure and psychological mechanisms of consciousness has a rich history, to which M. M. Bakhtin, G. G. Shpet, L. S. Vygotsky, and, later, A. N. Leont'ev and S. L. Rubinshtein all made significant contributions. It is our purpose in the present article to discuss only one aspect of this problem: the structure of individual consciousness. Pursuing the line of research delineated by Vygotsky, Leont'ev (1977) posed some cardinal questions: Of what is consciousness composed? How does it arise? What are its components? He called the latter the "formative elements" of consciousness. According to Leont'ev, there are three such "forming" elements: the sensory fabric of perception (or of an image), meaning, and sense. The inclusion of the sensory fabric in the structure of consciousness along with ostensive meaning and sense was a definite step forward along the path toward the ontologization of conceptions of consciousness.¹ But I think that individual consciousness construed in this way is still insufficiently ontological. Leont'ev's three "formative elements" do not completely account for the connection between consciousness and being (see M. M. Bakhtin, for whom consciousness "participates" in being and is essential for life). One might even reproach Leont'ev for a certain inconsistency: activity, although it is the source of consciousness, is itself not one of its "formative elements." Of course, he could answer this reproach by saying that the "formative elements" are structural elements, constituents, not generative elements. However, it seems to me that the distinction between constitutive and generative is very, very relative in any analysis of living consciousness, which is continually in the process of being constructed.     

New readers and interpretations of poly(ADP-ribosyl)ation

Poly(ADP-ribosyl)ation (PARylation), a protein post-translational modification that was originally connected to the DNA damage response, is now known to engage in a continuously increasing number of biological processes. Despite extensive research and ceaseless, important findings about its role and mode of action, poly(ADP-ribose) remains an enigma regarding its structural complexity and diversity. The recent identification and structural characterization of four different poly(ADP-ribose) binding motifs represents a quantum leap in the comprehension of how this molecule can be decoded. Moreover, the recent discovery of a direct connection between PARylation and poly-ubiquitylation in targeting proteins for degradation by the proteasome has paved the way for a new interpretation of this protein modification. These two novel aspects, poly(ADP-ribose) recognition and readout by the ubiquitylation/proteasome system are developed here.     

An Auditory Illusion of Infinite Tempo Change Based on Multiple Temporal Levels

Humans and a few select insect and reptile species synchronise inter-individual behaviour without any time lag by predicting the time of future events rather than reacting to them. This is evident in music performance, dance, and drill. Although repetition of equal time intervals (i.e. isochrony) is the central principle for such prediction, this simple information is used in a flexible and complex way that accommodates both multiples, subdivisions, and gradual changes of intervals. The scope of this flexibility remains largely uncharted, and the underlying mechanisms are a matter for speculation. Here I report an auditory illusion that highlights some aspects of this behaviour and that provides a powerful tool for its future study. A sound pattern is described that affords multiple alternative and concurrent rates of recurrence (temporal levels). An algorithm that systematically controls time intervals and the relative loudness among these levels creates an illusion that the perceived rate speeds up or slows down infinitely. Human participants synchronised hand movements with their perceived rate of events, and exhibited a change in their movement rate that was several times larger than the physical change in the sound pattern. The illusion demonstrates the duality between the external signal and the internal predictive process, such that people''s tendency to follow their own subjective pulse overrides the overall properties of the stimulus pattern. Furthermore, accurate synchronisation with sounds separated by more than 8 s demonstrate that multiple temporal levels are employed for facilitating temporal organisation and integration by the human brain. A number of applications of the illusion and the stimulus pattern are suggested.     

Theoretical approaches to holistic biological features: Pattern formation,neural networks and the brain-mind relation

The topic of this article is the relation between bottom-up and top-down, reductionist and “holistic” approaches to the solution of basic biological problems. While there is no doubt that the laws of physics apply to all events in space and time, including the domains of life, understanding biology depends not only on elucidating the role of the molecules involved, but, to an increasing extent, on systems theoretical approaches in diverse fields of the life sciences. Examples discussed in this article are the generation of spatial patterns in development by the interplay of autocatalysis and lateral inhibition; the evolution of integrating capabilities of the human brain, such as cognition-based empathy; and both neurobiological and epistemological aspects of scientific theories of consciousness and the mind.