Background: Loss of consciousness is an essential feature of general anesthesia. Although alterations of neural networks during anesthesia have been identified in the spatial domain, there has been relatively little study of temporal organization. Methods: Ten healthy male volunteers were anesthetized with an induction dose of propofol on two separate occasions. The duration of network...
We discuss the molecular and cognitive mechanisms of general anaesthesia and their relevance to the science of consciousness. General anaesthetics serve as an important tool to explore the transitions from conscious to unconscious processing, as these drugs rapidly induce a complete and reversible cessation of consciousness. With 40,000,000 patients undergoing general anaesthesia each year in...
Abstract Consciousness is a multidisciplinary subject of inquiry. The extent of clinical contributions to the field of consciousness studies has yet to be investigated. The goal of this study was to assess the degree of clinically related articles in the literature of consciousness studies through a systematic evaluation. Three journals systematically identified (Consciousness and Cognition,...
Understanding dreams has long been considered fundamental to the development of a theory of consciousness. Evidence from neurobiology and neuroimaging research has paved the way for new theories of dreaming that are empirically supported. In this article we argue that dreaming is a unique state of consciousness that incorporates 3 temporal dimensions: experience of the present, processing of...
Philosophical (p-) zombies are constructs that possess all of the behavioral features and responses of a sentient human being, yet are not conscious. P-zombies are intimately linked to the hard problem of consciousness and have been invoked as arguments against physicalist approaches. But what if we were to invert the characteristics of p-zombies? Such an inverse (i-) zombie would possess all...
Abstract The cognitive unbinding paradigm suggests that the synthesis of cognitive information is attenuated by general anesthesia. Here, we investigated the functional organization of brain activities in the conscious and anesthetized states, based on characteristic functional segregation and integration of electroencephalography (EEG). EEG recordings were obtained from 14 subjects undergoing...
The cognitive binding problem is a central question in the study of consciousness: how does the brain synthesize its modal and submodal processing systems to generate a unity of conscious experience? This essay considers several solutions to the binding problem, as well as their shortcomings. In particular, the current theory of neural synchronization as the basis for binding and consciousness...
University of Michigan Medical School Ann Arbor, Michigan A version of this article appeared in the Bulletin of Anesthesia History (July, 2005). The author thanks Dr Edward Lowenstein, Dr George Battit, Dr Bucknam McPeek, and Dr Warren Zapol of the Massachusetts General Hospital and Dr Johnathan Moreno of the University of Virginia for their interest and helpful contributions to this project....
The nature and mechanism of human consciousness is emerging as one of the most important scientific and philosophical questions of the 21st century. Disregarded as a subject of serious inquiry throughout most of the 20th century, it has now regained legitimacy as a scientific endeavor. The investigation of consciousness and the mechanisms of general anesthesia have begun to converge. In the...
Understanding the relationship of conscious states to large-scale brain dynamics remains a central challenge in neuroscience. Here, diverse pharmacological and physiological perturbations, including psychedelic states, sleep, and propofol sedation, were used to examine integration-segregation organization of brain networks across altered states of consciousness in humans using functional MRI....