Investigations of Hypesthesia: Using Anesthetics to Explore Relationships between Consciousness, Learning, and Memory

This paper discusses the ways in which anesthetic agents can be used to investigate the role of awareness in learning and memory. It reviews research into learning during light, subclinical anesthesia, termedhypesthesia.This research suggests that the effects of anesthetics on implicit and explicit memory are roughly comparable, although implicit memory for simple stimuli may resist the effects of very low doses of anesthetic. In addition, this paper reports experimental data demonstrating that long-term retention of information is prevented by doses of anesthetic that are low enough to permit awareness and even short-term memory of auditory stimuli. Overall, these findings are consistent with the hypothesis (e.g., Caseley-Rondi, 1996) that frontal lobe function is particularly sensitive to anesthetics. They raise theoretical and practical questions about the necessity of consciousness for learning and about interpretation of the evidence for learning during surgery under general anesthesia.     

Learning under anesthesia: Checking the light in the fridge? Commentary on Deeprose and Andrade (2006)

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.     

Is priming during anesthesia unconscious?

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 (Merikle & Daneman, 1996) 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.     

内隐序列学习意识的具身机制

内隐序列学习意识已有三类理论如全局工作平台理论、神经可塑性理论、新异刺激理论都忽略了身体感受的关键因素, 难以揭示意识产生的根本原因。具身意识理论和研究发现, 运动/情感镜像神经元系统及与自我、认知控制系统的交互, 是初级/高级意识产生的本源, 但未涉及内隐序列学习规则意识这个对人类学习认知至关重要的领域。内隐序列学习研究实质上已接近揭示其学习机制正是感知觉运动具身学习, 其意识机制很可能是感知觉运动/情感具身意识, 并且其意识加工脑区与具身意识脑区有关键重合。未来研究可采用Granger因果大脑网络技术证明内隐序列学习意识的具身本源, 并考察已有三类意识理论的具身基础, 以及探索意识影响因素的具身机制。     

人工语法学习中意识加工的渐进发展

内隐学习研究致力于探讨学习活动的意识加工程度, 当前相关的研究逻辑从传统的意识二分观转向渐进意识假设。本研究通过对人工语法范式进行改造, 并借鉴加工分离程序的有关思想, 在学习阶段引入双重测量任务, 并根据双重任务成绩计算分离出相应学习时段的意识与无意识成分的贡献分数, 从而考察在内隐学习过程中两种加工成分的动态变化特征。研究结果支持渐进意识假设, 在学习进程中, 无意识成分和意识成分都呈现出渐进发展的趋势; 而随学习的深入, 两种成分呈现出不同的变化模式, 中后期意识加工快速增长, 无意识加工则保持平缓发展, 渐进意识系统整体呈现向外显学习推进的发展态势。     

The brain basis of a "consciousness monitor": scientific and medical significance.

Surgical patients under anesthesia can wake up unpredictably and be exposed to intense, traumatic pain. Current medical techniques cannot maintain depth of anesthesia at a perfectly stable and safe level; the depth of unconsciousness may change from moment to moment. Without an effective consciousness monitor anesthesiologists may not be able to adjust dosages in time to protect patients from pain. An estimated 40,000 to 200,000 midoperative awakenings may occur in the United States annually. E. R. John and coauthors present the scientific basis of a practical "consciousness monitor" in two articles. One article is empirical and shows widespread and consistent electrical field changes across subjects and anesthetic agents as soon as consciousness is lost; these changes reverse when consciousness is regained afterward. These findings form the basis of a surgical consciousness monitor that recently received approval from the U.S. Food and Drug Administration. This may be the first practical application of research on the brain basis of consciousness. The other John article suggests theoretical explanations at three levels, a neurophysiological account of anesthesia, a neural dynamic account of conscious and unconscious states, and an integrative field theory. Of these, the neurophysiology is the best understood. Neural dynamics is evolving rapidly, with several alternative points of view. The field theory sketched here is the most novel and controversial.     

“Paradox of slow frequencies” – Are slow frequencies in upper cortical layers a neural predisposition of the level/state of consciousness (NPC)?

Consciousness research has much focused on faster frequencies like alpha or gamma while neglecting the slower ones in the infraslow (0.001–0.1 Hz) and slow (0.1–1 Hz) frequency range. These slower frequency ranges have a “bad reputation” though; their increase in power can observed during the loss of consciousness as in sleep, anesthesia, and vegetative state. However, at the same time, slower frequencies have been conceived instrumental for consciousness. The present paper aims to resolve this paradox which I describe as “paradox of slow frequencies”. I first show various data that suggest a central role of slower frequencies in integrating faster ones, i.e., “temporo-spatial integration and nestedness”. Such “temporo-spatial integration and nestedness” is disrupted during the loss of consciousness as in anesthesia and sleep leading to “temporo-spatial fragmentation and isolation” between slow and fast frequencies. Slow frequencies are supposedly mediated by neural activity in upper cortical layers in higher-order associative regions as distinguished from lower cortical layers that are related to faster frequencies. Taken together, slower and faster frequencies take on different roles for the level/state of consciousness. Faster frequencies by themselves are sufficient and thus a neural correlate of consciousness (NCC) while slower frequencies are a necessary non-sufficient condition of possible consciousness, e.g., a neural predisposition of the level/state of consciousness (NPC). This resolves the “paradox of slow frequencies” in that it assigns different roles to slower and faster frequencies in consciousness, i.e., NCC and NPC. Taken as NCC and NPC, fast and slow frequencies including their relation as in “temporo-spatial integration and nestedness” can be considered a first “building bloc” of a future “temporo-spatial theory of consciousness” (TTC) (Northoff, 2013; Northoff, 2014b; Northoff & Huang, 2017).     

国内近十年来意识和无意识关系研究的新成就

近十年来,国内掀起了从自然科学途径进行意识和无意识对比研究的新热潮,尤其在实验范式的引进、修正、完善和模型建构方面,做出了中国学者自己的贡献。错误记忆、内隐时间及不注意视盲等新领域的触及代表了国内学者在意识研究内容上的丰富。“钢筋水泥”、“意识涌现”及“车站监视室”等模型的提出,代表了中国学者在意识研究理论方面的创新。当前国内意识研究与国外基本同步,但存在着“研究领域泛化,神经机制探讨有限,跨学科整合力度有待深化”的问题。     

The directionality and functional organization of frontoparietal connectivity during consciousness and anesthesia in humans

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.     

试析内隐学习的意识-无意识兼容性

内隐学习研究初期,其无意识特点揭示了区别于外显学习的独特本质。但随着研究的深入,内隐学习逐渐昭显出与意识的丝丝联系。本文从此出发,探讨内隐学习的意识-无意识的兼容特点,具体从理论和实证两方面探讨内隐学习和无意识的联系,从次要任务研究、内隐学习的理解性以及内隐知识的发展三方面阐述内隐学习和意识的联系。     

学习技能形成中的脑加工

对运动学习,视知觉学习,镜像阅读,语法学习和动词产生学习的脑实验研究,主要有单通路调节加工模型和双通路转换加工模型,实验侧重研究学习的时间进程。     

A field theory of consciousness.

This article summarizes a variety of current as well as previous research in support of a new theory of consciousness. Evidence has been steadily accumulating that information about a stimulus complex is distributed to many neuronal populations dispersed throughout the brain and is represented by the departure from randomness of the temporal pattern of neural discharges within these large ensembles. Zero phase lag synchronization occurs between discharges of neurons in different brain regions and is enhanced by presentation of stimuli. This evidence further suggests that spatiotemporal patterns of coherence, which have been identified by spatial principal component analysis, may encode a multidimensional representation of a present or past event. How such distributed information is integrated into a holistic precept constitutes the binding problem. How a precept defined by a spatial distribution of nonrandomness can be subjectively experienced constitutes the problem of consciousness. Explanations based on a discrete connectionistic network cannot be reconciled with the relevant facts. Evidence is presented herein of invariant features of brain electrical activity found to change reversibly with loss and return of consciousness in a study of 176 patients anesthetized during surgical procedures. A review of relevant research areas, as well as the anesthesia data, leads to a postulation that consciousness is a property of quantum-like processes, within a brain field resonating within a core of structures, which may be the neural substrate of consciousness. This core includes regions of the prefrontal cortex, the frontal cortex, the pre- and paracentral cortex, thalamus, limbic system, and basal ganglia.     

Consciousness lost and found: subjective experiences in an unresponsive state

Anesthetic-induced changes in the neural activity of the brain have been recently utilized as a research model to investigate the neural mechanisms of phenomenal consciousness. However, the anesthesiologic definition of consciousness as “responsiveness to the environment” seems to sidestep the possibility that an unresponsive individual may have subjective experiences. The aim of the present study was to analyze subjective reports in sessions where sedation and the loss of responsiveness were induced by dexmedetomidine, propofol, sevoflurane or xenon in a nonsurgical experimental setting. After regaining responsiveness, participants recalled subjective experiences in almost 60% of sessions. During dexmedetomidine sessions, subjective experiences were associated with shallower “depth of sedation” as measured by an electroencephalography-derived anesthesia depth monitor. Results confirm that subjective experiences may occur during clinically defined unresponsiveness, and that studies aiming to investigate phenomenal consciousness under sedative and anesthetic effects should control the subjective state of unresponsive participants with post-recovery interviews.     

Future directions for implicit learning: Toward a clarification of issues associated with knowledge representation and consciousness

Areas of agreement and disagreement regarding knowledge representation and consciousness within implicit learning research are reviewed. It is argued that further progress in the field requires more precise definitions of abstract and episodic knowledge, and of conscious and unconscious forms of cognition. In particular, we argue that implicit learning research should be informed by more general theories of memory and performance, and that concepts such as consciousness are unlikely to act as explanatory constructs within this approach.     

Toward a unified theory of narcosis: brain imaging evidence for a thalamocortical switch as the neurophysiologic basis of anesthetic-induced unconsciousness

A unifying theory of general anesthetic-induced unconsciousness must explain the common mechanism through which various anesthetic agents produce unconsciousness. Functional-brain-imaging data obtained from 11 volunteers during general anesthesia showed specific suppression of regional thalamic and midbrain reticular formation activity across two different commonly used volatile agents. These findings are discussed in relation to findings from sleep neurophysiology and the implications of this work for consciousness research. It is hypothesized that the essential common neurophysiologic mechanism underlying anesthetic-induced unconsciousness is, as with sleep-induced unconsciousness, a hyperpolarization block of thalamocortical neurons. A model of anesthetic-induced unconsciousness is introduced to explain how the plethora of effects anesthetics have on cellular functioning ultimately all converge on a single neuroanatomic/neurophysiologic system, thus providing for a unitary physiologic theory of narcosis related to consciousness.     

Building Leadership,Capacity, and Power to Advance Health Equity and Justice through Community‐Engaged Research in the Midwest

The Health Equity Advancement Lab (HEAL) at the University of Iowa College of Public Health began in 2012 to support students, researchers, and community members interested in tackling persistent health inequities through a community‐based participatory research (CBPR) approach. Using concepts from critical consciousness theory, we developed an approach to building students’, faculty members’, and community partners’ capacity to engage in CBPR to promote health equity that involved immersion in developing CBPR projects. Our paper describes the evolution of HEAL as a facilitating structure that provides a support network and engages diverse stakeholders in critical reflection as they participate in research to advance health equity, and resulting political efficacy and social action. We describe one HEAL‐affiliated research project that employs a CBPR approach and has a strong focus on providing transformative learning experiences for students, faculty, and community members. We highlight challenges, successes, and lessons learned in the application of critical consciousness as a framework that engages diverse academic and community partners seeking to promote health equity. We argue that critical consciousness is a relevant theoretical framework to promote transformative learning among students, faculty, and community partners to promote health equity research in diverse communities.     

效应器在动作序列学习中的作用机制探析

动作序列学习是动作技能学习的重要组成部分,其中大部分动作序列学习都有效应器参与。目前有关效应器在动作序列学习中的作用机制存在两种观点：一是依存于效应器的观点,即动作序列技能的获得依附于具体的效应器,不可向其他效应器迁移,其学习的本质是建立反应或肌肉间的联结。二是独立于效应器的观点,即动作序列技能的获得并不依存于具体效应器,某个效应器获得的技能可以向其他效应器迁移,其学习的本质是建立抽象的刺激表征联结。效应器作用机制随练习程度、意识状态及其他条件的不同而有所变化。     

内隐学习意识性研究的两种理论取向:二分与渐进

传统的内隐学习研究范式大多致力于意识与无意识加工的操作性分离。随着学习任务和测量手段的改进,越来越多的研究发现量化渐变比二元分离能更好地兼容实验数据。本文对认知领域中与二分和渐进两种取向相关的理论框架和实证研究进行介绍和评价,指出意识的二分与渐进假设是源自不同的概念定义层次的理论框架,即功能性概念和解释性概念,因而对现象学数据具有不同的解释效力。它们的共存提供了不同的研究视角,丰富了我们对内隐学习活动的认识。     

The role of awareness in Pavlovian conditioning: empirical evidence and theoretical implications

This article reviews research over the past decade concerning the relationship between Pavlovian conditioning and conscious awareness. The review covers autonomic conditioning, conditioning with subliminal stimuli, eyeblink conditioning, conditioning in amnesia, evaluative conditioning, and conditioning under anesthesia. The bulk of the evidence is consistent with the position that awareness is necessary but not sufficient for conditioned performance, although studies suggestive of conditioning without awareness are identified as worthy of further investigation. Many studies have used inadequate measures of awareness, and strategies for increasing validity and sensitivity are discussed. It is concluded that conditioning may depend on the operation of a propositional system associated with consciousness rather than a separate, lower level system.     

A neural model of normal and abnormal learning and memory consolidation: adaptively timed conditioning,hippocampus, amnesia,neurotrophins, and consciousness

How do the hippocampus and amygdala interact with thalamocortical systems to regulate cognitive and cognitive-emotional learning? Why do lesions of thalamus, amygdala, hippocampus, and cortex have differential effects depending on the phase of learning when they occur? In particular, why is the hippocampus typically needed for trace conditioning, but not delay conditioning, and what do the exceptions reveal? Why do amygdala lesions made before or immediately after training decelerate conditioning while those made later do not? Why do thalamic or sensory cortical lesions degrade trace conditioning more than delay conditioning? Why do hippocampal lesions during trace conditioning experiments degrade recent but not temporally remote learning? Why do orbitofrontal cortical lesions degrade temporally remote but not recent or post-lesion learning? How is temporally graded amnesia caused by ablation of prefrontal cortex after memory consolidation? How are attention and consciousness linked during conditioning? How do neurotrophins, notably brain-derived neurotrophic factor (BDNF), influence memory formation and consolidation? Is there a common output path for learned performance? A neural model proposes a unified answer to these questions that overcome problems of alternative memory models.