Consciousness and Anesthesia

Informed consent for anesthesia is an ethical and legal requirement. A patient must have adequate decision-making capacity as a prerequisite to informed consent. In determining whether a patient has sufficient DMC, anesthesiologists must draw on their knowledge of DMC. Knowledge gaps regarding DMC may result in incorrect assessments of patients’ capacity. This could translate to an informed consent process that is ethically and legally unsound. This study examined the DMC-related knowledge of anesthesiologists in a group of four university-affiliated hospitals. The (...) findings suggest that anesthesiologists have several areas of knowledge deficiency regarding DMC and DMC assessment. These findings could inform the development of undergraduate and postgraduate curricula. (shrink)

Philosophy and anaesthesiology are disciplines that are rarely associated despite their respective interests in human consciousness. In this paper, we consider the advantages of integrating anaesthesiology and philosophy in the endeavour of discovering the neural correlates of state consciousness. We venture the following twopart argument. First, we argue that philosophical debates about the correlation conditions for state consciousness can be improved by focusing on how anaesthesiologists actually measure and study consciousness in practice. We present Integrated Information Theory as a promising (...) framework for discriminating features hitherto considered relevant to the identification of the neural correlates of state consciousness. Second, we argue that an improved philosophical understanding of what comprises the correlation conditions for state consciousness can, in turn, advance anaesthesiological methodologies; not only can it improve how potential evidence is gathered and assessed, but it can aid in the prevention of intraoperative awareness, increasing patient safety and well-being. (shrink)

In this paper we discuss the two-system framework, examine its strengths, point out a fundamental weakness concerning the unity of conscious experience, and then propose a new hypothesis that avoids that weakness and other related concerns. According to our strong emergence hypothesis, what emerges are not merely mental properties in specialized, distributed neural areas, but also a new, irreducibly singular entity that functions in a recurrent manner to integrate its mental properties and to rewire its brain. We argue that the (...) former function is suggested, in part, by the effects of anesthetics on sensory integration, and that the latter function is suggested by evidence garnered from the neuroscience of mindfulness, constraint-induced movement therapy for stroke, and neuroimaging data surrounding mental illness. We then discuss how our strong emergence hypothesis relates to the description and treatment of neuropsychiatric disorders. Finally, potential objections are addressed. (shrink)

For patients under anesthesia, it is extremely important to be able to ascertain from a scientific, third person point of view to what extent consciousness is correlated with specific areas of brain activity. Errors in accurately determining when a patient is having conscious states, such as conscious perceptions or pains, can have catastrophic results. Here, I argue that the effects of (at least some kinds of) anesthesia lend support to the notion that neither basic sensory areas nor the prefrontal cortex (...) (PFC) is sufficient to produce conscious states. I also argue that it this is consistent with and supportive of the higher-order thought (HOT) theory of consciousness. I therefore disagree in some ways with Mehta and Mashour (2013), who argue that evidence from anesthesia mainly favors a first-order representational (FOR) theory, as opposed to HOT theory (and many other theories, for that matter). (shrink)

A key contention of Klein & Barron (2016) is that consciousness does not depend on cortical structures. A critical appraisal suggests they have overestimated the strength of their evidence.

The attitudes of patients' to consent have changed over the years, but there has been little systematic study of the attitudes of anaesthetists and surgeons in this process. We aimed to describe observations made on the attitudes of medical professionals working in the UK to issues surrounding informed consent.

Consciousness, Awareness, and Anesthesia is a multidisciplinary approach to both the scientific problem of consciousness and the clinical problem of awareness during general anesthesia.

Information processing that subserves conscious cognitive functions is thought to involve recurrent signaling through feedforward and feedback loops among hierarchically arranged functional regions of the cerebral cortex. In the current issue of Consciousness and Cognition, Lee et al. report that loss of consciousness, as produced by a bolus injection of the general anesthetic propofol to human volunteers, was accompanied by a decrease in wide-band EEG feedback connectivity from frontal cortex to parietal cortex, confirming a prediction from previous experimental studies. Interestingly, (...) frontoparietal feedback connectivity did not fully recover after the anesthetic effect wore off and the subjects first opened their eyes in response to a verbal command. Possible interpretations of the results and their implications with respect to the neural correlates of consciousness and unconsciousness are discussed. (shrink)

Frontoparietal connectivity has been suggested to be important in conscious processing and its interruption is thought to be one mechanism of general anesthesia. Data in animals demonstrate that feedforward processing of information may persist during the anesthetized state, while feedback processing is inhibited. We investigated the directionality and functional organization of frontoparietal connectivity in 10 human subjects anesthetized with propofol on two separate occasions. Multichannel electroencephalography and a computational method of assessing directed functional connectivity were employed. We demonstrate that directed (...) feedback connectivity is diminished with loss of consciousness and returns with responsiveness to verbal command. We also applied the Dendrogram classification method to assess the global organization of directed functional connectivity during consciousness and anesthesia. We demonstrate a state-specific hierarchy and subject-specific subhierarchy in functional organization. These data support the hypothesis that specific states of human consciousness are defined by specific states of frontoparietal connectivity. (shrink)

The cognitive unbinding paradigm suggests that the synthesis of neural information is attenuated by general anesthesia. Here, we analyzed the functional organization of brain activities in the conscious and anesthetized states, based on functional segregation and integration. Electroencephalography recordings were obtained from 14 subjects undergoing induction of general anesthesia with propofol. We quantified changes in mean information integration capacity in each band of the EEG. After induction with propofol, mean information integration capacity was reduced most prominently in the γ band (...) of the EEG . Furthermore, we demonstrate that loss of consciousness is reflected by the breakdown of the spatiotemporal organization of γ waves. We conclude that induction of general anesthesia with propofol reduces the capacity for information integration in the brain. These data directly support the information integration theory of consciousness and the cognitive unbinding paradigm of general anesthesia. (shrink)

This is a response to James Dubois’ “Is anesthesia intrinsically wrong?” I do not address many of the claims in this article but only DuBois’ use of the moral evaluation of the medical use of anesthesia as a counter example to two lines of reasoning developed to defend the traditional Catholic prohibition of contraception. Elizabeth Anscombe's dialectical defense of this teaching does not imply that such a defense must logically apply to the use of anesthesia. John Finnis’ defense of this (...) teaching on the basis of a natural law argument does not imply that consciousness is a basic human good. (shrink)

This article engages two fundamentally different kinds of so-called natural law arguments in favor of specific moral absolutes: Elizabeth Anscombe's claim that certain actions are known to be intrinsically wrong through intuition, and John Finnis's claim that such actions are known to be wrong because they involve acting directly against a basic human good. Both authors maintain, for example, that murder and contraceptive sexual acts are known to be wrong, always and everywhere, through their respective epistemological lens. This article uses (...) the counter-example of anesthesia to challenge these two approaches to substantiating natural law claims. The paper concludes by rejecting the view shared by Professors Finnis and Anscombe that once one rejects these foundations for moral absolutes, one is left with moral subjectivism. In fact, one is left with moral absolutes of a more restricted nature, which are known philosophically, and with more robust moral absolutes held on religious grounds. Virtues are needed in the moral life, among other reasons, because such norms require discernment and integrity for their correct application. (shrink)

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 of the behavioral features and responses of an insensate being yet would nonetheless be conscious. While p-zombies are logically possible (...) but naturally improbable, an approximation of i-zombies actually exists: individuals experiencing what is referred to as “anesthesia awareness.” Patients under general anesthesia may be intubated (preventing speech), paralyzed (preventing movement), and narcotized (minimizing response to nociceptive stimuli). Thus, they appear—and typically are—unconscious. In 1-2 cases/1000, however, patients may be aware of intraoperative events, sometimes without any objective indices. Furthermore, a much higher percentage of patients (22% in a recent study) may have the subjective experience of dreaming during general anesthesia. P-zombies confront us with the hard problem of consciousness—how do we explain the presence of qualia? I-zombies present a more practical problem—how do we detect the presence of qualia? The current investigation compares p-zombies to i-zombies and explores the “hard problem” of unconsciousness with a focus on anesthesia awareness. (shrink)

Amidst competing claims of beauty, truth and goodness, Trajan, a young man named after a once celebrated Roman Emperor, attempts to decipher why it is that Kant is wrong, love is capricious, and why you should never take advice from a puppet.

In this commentary we discuss the possibility of subcortical consciousness and its implications for fetal anesthesia and analgesia. We review the neural development of structural and functional elements that may participate in conscious representation, with a particular focus on the experience of pain. (Published Online May 1 2007).

Grossi, Antonio This article discusses anaesthesia, the role of the anaesthetist and its ethical challenges. In the current political climate of task substitution and de-professionalisation, it is worth considering the role of the anaesthetist and the relevant ethical issues pertaining to this endeavour.

Anesthesia research has focused on showing learning in the absence of awareness for good practical reasons. Crucially, continued learning during otherwise clinically adequate anesthesia may affect patients’ well-being on recovery. Theoretically, preserved perceptual priming during anesthesia offers a useful starting point for consciousness research by determining the limits of memory function during minimal consciousness. The big question for consciousness research is not to demonstrate absolutely unconscious processing, but rather to map out the cognitive and neurobiological processes that enable conscious experience (...) itself. (shrink)

General anesthesia provides an alternative to typical laboratory paradigms for investigating implicit learning. We assess the evidence that a simple type of learning—priming—can occur without consciousness. Although priming has been shown to be a small but persistent phenomenon in surgical patients there is reason to question whether it occurs implicitly due to problems in detecting awareness using typical clinical signs. This paper reviews the published studies on priming during anesthesia that have included a measure of awareness or of anesthetic depth. (...) We conclude that perceptual priming, but not conceptual priming, takes place in the absence of conscious awareness. (shrink)

feelings (brainstem, limbic system). The best scientific synchrony and consciousness.21,27 Anesthesiology, V 105, No 2, Aug 2006.

Cataract surgery has evolved rapidly over the last decade. Previously such cases required admission for prolonged postoperative convalescence. However, currently such procedures are carried out as day cases. An area where significant change has evolved is the role of anaesthesia in cataract surgery.Recently, a growing number of surgeons have been performing cataract surgery using topical drops to achieve anaesthesia. However, case selection and operator experience impose a limit on the use of topical anaesthesia.1 Other local techniques for delivering ….

Research on learning under anesthesia has focused on showing that learning is possible in the absence of awareness. However, a simple dissociation between learning and awareness is conclusive only under strong additional assumptions, and the actual state of consciousness of an anesthetized person is difficult to determine. Instead of trying to establish complete unconsciousness, one might employ gradual anesthesia to experimentally vary the level of consciousness in a controlled fashion, checking whether cognitive processes exist that can change in opposite direction (...) to measures of awareness. (shrink)

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.

While working to build his aesthetic theory from the qualities of normal, healthy experience, John Dewey diagnoses a rarely recognized experiential ailment -- what might be called the anesthetic malady. This illness generally results when experience is deprived of meaning due to the poverty of the predominant forms of activity available in one's environment. In Dewey's theory of aesthetic experience lies an easily overlooked social/political approach that predates, by almost half a century, recent social theoretical concerns in phenomenology and everyday (...) aesthetics. Dewey takes notice of experience and prompts inquiry into sometimes obviously important, but often dismissed as irrelevant and mundane, paths. (shrink)

According to the mental models theory, reasoning performance is primarily influenced by the number of models of a problem that can be constructed. This study investigates whether the content of the model may also influence performance. Linear reasoning problems were devised that either described a believable (script-consistent) or an unbelievable (script-inconsistent) order of actions. The results of two experiments showed that conclusions were inferred more slowly and less accurately on the basis of an unbelievable model than on a believable one. (...) Experiment 2 revealed that script knowledge facilitated as well as impeded reasoning performance. Conclusion evaluation was faster and more accurately for script-consistent problems than for neutral problems, whereas model construction and conclusion evaluation occurred respectively more slowly and less accurately for script-inconsistent problems than for neutral problems. These results show that the content of the model is a noteworthy factor influencing reasoning performance. (shrink)

“Informed consent” is a legal instrument that allows individuals to define their own interests and to protect their bodily privacy. In current medical practice, patients who have consented to surgery are considered to have implied consent to anaesthesia, even though anaesthesia is associated with its own particular set of risks and consequences that are quite separate from those associated with surgery. In addition, anaesthetists often perform interventions that are the only medical treatment received by a patient. Anaesthetists, therefore, should always (...) obtain separate consent for anaesthesia, and should regard the process of consent as a stimulus for active, fluid reciprocal discussion with patients about treatment options. (shrink)