家鸽不同状态下脑电节律特异性分析

人类大脑神经电活动的不同节律与不同的状态有关,而其他物种如鸟类不同状态下脑信号的节律特异性尚不明确。本文通过分析家鸽(Columbaliviadomestica)在麻醉昏迷、清醒安静、自由探索三种典型状态下的局部场电位(LFP)信号,研究家鸽不同意识状态下神经电活动的节律特异性。首先采集不同状态下的LFP信号,提取δ(1～4 Hz)、θ(4～8 Hz)、α(8～12 Hz)、β(15～30 Hz)、γ(30～60 Hz)五个节律;然后使用小波变换进行时频分析,通过统计时频图的定性观察和小波能量的统计分析,使用Friedman检验进行统计假设检验,研究各状态不同节律的特异性,并基于样本熵分析信号复杂度,探索产生这种节律特异性的可能原因。结果表明,随着意识越来越清晰,较低频的δ、θ、α节律受到明显抑制(P 0.001),而较高频的γ节律活动明显增强(P 0.001);样本熵的分析表明,这可能是由于节律频带越高,信号样本熵越大,对应了从麻醉、清醒到自由探索意识清晰程度的提高。家鸽不同状态下神经电活动节律特异性的研究,有助于增进对不同物种脑信号节律编码机制的理解。     

某些剧烈刺激对脑乳酸的影响

我们曾以氨作为脑功能活动的指标对大鼠大脑进行过一些观察(于宗瀚、徐京华,1962)。与氨相似,乳酸也是脑内的一种不稳定物质。在不同的功能状态下,脑内乳酸水平会有所改变(Richer,Dawson,1948)。因此对于研究脑的功能生物化学,乳酸也是一个可利用的指标。在某些剧烈条件下,例如缺氧、麻醉、噪声和颠覆等,动物脑的各部位处于什么状态呢?对于听敏感的大鼠,这是研究癫癎的实验医学动物;其大脑究竟与一般大鼠有什么区别呢?在类癫痫发作后又有些什么变化呢?本工作即试图以乳酸为指标,对这些情况进行观察。     

感觉、意识、情绪和智力(3)

"有意识"为动物能够感觉的状态,以区别于植物无感觉(因此无意识)的状态和动物深度睡眠、昏迷、麻醉和死亡等"无意识"状态。只有302个神经细胞的线虫就具有感觉和意识,能够睡眠、被麻醉和对毒品上瘾,所使用的分子机制也与高等动物相同,说明感觉和意识的产生并不需要大量的神经细胞和复杂的脑结构,而是伴随着神经系统而出现的。"好"和"坏"的感觉会使动物产生情绪,是动物趋利避害的动力,也导致动物个性和智力的出现。     

感觉、意识、情绪和智力(1)

"有意识"为动物能够感觉的状态,以区别于植物无感觉(因此无意识)的状态和动物深度睡眠、昏迷、麻醉和死亡等"无意识"状态。只有302个神经细胞的线虫就具有感觉和意识,能够睡眠、被麻醉和对毒品上瘾,所使用的分子机制也与高等动物相同,说明感觉和意识的产生并不需要大量的神经细胞和复杂的脑结构,而是伴随着神经系统而出现的。"好"和"坏"的感觉会使动物产生情绪,是动物趋利避害的动力,也导致动物个性和智力的出现。     

感觉、意识、情绪和智力(2)

"有意识"为动物能够感觉的状态,以区别于植物无感觉(因此无意识)的状态和动物深度睡眠、昏迷、麻醉和死亡等"无意识"状态。只有302个神经细胞的线虫就具有感觉和意识,能够睡眠、被麻醉和对毒品上瘾,所使用的分子机制也与高等动物相同,说明感觉和意识的产生并不需要大量的神经细胞和复杂的脑结构,而是伴随着神经系统而出现的。"好"和"坏"的感觉会使动物产生情绪,是动物趋利避害的动力,也导致动物个性和智力的出现。     

麻醉-觉醒周期中非洲爪蟾的大脑复杂度研究

全身麻醉是药物诱导下中枢神经系统的抑制状态,是长时间手术操作和有创实验顺利进行的保证。丘脑-皮层环路(特别是丘脑)可能在麻醉-觉醒调控中起着重要作用,但丘脑是否是最重要的调控脑区、调控时是否存在偏侧性尚不清楚。本研究以非洲爪蟾Xenopus laevis为动物模型,在其端脑、间脑、中脑左右两侧分别埋植电极,在鱼安定诱导下进行全身麻醉,连续记录动物在"麻醉前清醒-给药-恢复-麻醉后清醒"过程中的脑电信号,计算各时期的Lempel-Ziv复杂度(LZC)。结果显示:不同状态下的LZC值显著不同,清醒时最大,深度麻醉时最小;给药时长与各脑区LZC值间的显著相关性主要存在于右侧大脑,特别是右侧丘脑。说明LZC可以较好地刻画麻醉-觉醒周期,且右侧丘脑在麻醉-觉醒调控中可能起着重要作用。     

医院外突发急症现场自救互求知识讲座（七）——突然意识丧失（1）

1　意识丧失的概念意识是人的头脑对于客观世界的反映 ,是人脑高级活动的能力的表现 ,它包括思维、记忆、情感、定向力、言语、视听及各种技巧活动等等。有了意识 ,我们才有从事从简单到复杂的各项活动及对自然界发生的事变迅速作出反应的能力。如果某人突然丧失了这种能力 ,他就会立即表现为“昏过去”,也就是失去知觉 ,失去了判断、思维、言语及行动等能力 ,这就是我们所说的意识丧失。2　导致患者突然意识丧失的疾病意识丧失也被称为意识不清或神志不清 ,常见于 3种情况 :短暂的、一过性的意识丧失称为晕厥 ;持久的、有心跳呼吸存在的意…     

脑皮层和自主神经活动的因果作用

精神紧张、焦虑等脑活动可以导致心脏疾病,而冥想能够改善心脏功能.采用心率变异性、有向传递函数和校正条件熵的方法研究了不同脑任务引起心脏功能的变化以及皮层脑活动和心脏活动的耦合模式.结果表明,意识活动可以通过抑制交感神经减慢心率,通过抑制副交感神经和激活交感神经加快心率.并且意识活动调节自主神经过程中脑皮层中央后区到前区的信息流增加,心脑间的耦合程度显著增强.有向传递函数和校正条件熵方法有望成为分析脑电信号的功能耦合及脑到心脏信息传递的有力工具.     

同步脑电-功能磁共振成像技术对儿童失神性癫痫的研究

儿童失神癫痫是一类常见的原发全面性癫痫,表现为无抽搐性的阵发性意识丧失,以及3 Hz左右的头皮脑电全面慢波发放.应用同步记录头皮脑电与功能磁共振(simultaneous eleetroencephalography-functional magnetic resonance imaging,EEG-fMRI)技术,可...     

仙琴蛙对不同类型声音的感知差异研究

既往研究发现听觉感知包括对声音信号的觉察、感觉、注意和知觉等多个认知过程,但依然不清楚大脑如何对不同类型的复杂声音信号(如同种鸣声和其他声音)进行解码和处理,以及在感知不同类型声音信号时大脑活动的动态特征.本研究记录了在随机播放白噪声和洞内鸣叫声音刺激时仙琴蛙Nidirana daunchina的左右端脑、间脑和中脑的...     

Development of a Data Management Tool for Investigating Multivariate Space and Free Will Experiences in Virtual Reality

Virtual reality (VR) has become mature enough to be successfully used in clinical applications such as exposure therapy, pain distraction, and neuropsychological assessment. However, we now need to go beyond the outcome data from this research and conduct the detailed scientific investigations required to better understand what factors influence why VR works (or doesn’t) in these types of clinical applications. This knowledge is required to guide the development of VR applications in the key areas of education, training, and rehabilitation and to further evolve existing VR approaches. One of the primary assets obtained with the use of VR is the ability to simulate the complexity of real world environments, within which human performance can be tested and trained. But this asset comes with a price in terms of the capture, quantification and analysis of large, multivariate and concurrent data sources that reflect the naturalistic behavioral interaction that is afforded in a virtual world. As well, while achieving realism has been a main goal in making convincing VR environments, just what constitutes realism and how much is needed is still an open question situated firmly in the research domain. Just as in real “reality,” such factors in virtual reality are complex and multivariate, and the understanding of this complexity presents exceptional challenges to the VR researcher. For certain research questions, good behavioral science often requires consistent delivery of stimuli within tightly controlled lab-based experimental conditions. However, for other important research questions we do not want to constrain naturalistic behavior and limit VR’s ability to replicate real world conditions, simply because it is easier to study human performance with traditional lab-based methodologies. By doing so we may compromise the very qualities that comprise VR’s unique capacity to mimic the experiences and challenges that exist in everyday life. What is really needed to address scientific questions that require natural exploration of a simulated environment are more usable and robust tools to instrument, organize, and visualize the complex data generated by measurements of participant behaviors within a virtual world. This paper briefly describes the rationale and methodology of an initial study in an ongoing research program that aims to investigate human performance within a virtual environment where unconstrained “free will” exploratory behavior is essential to research questions that involve the relationships between physiology, emotion, and memory. After a discussion of the research protocol and the types of data that were collected, we describe a novel tool that was borne from our need to more efficiently capture, manage, and explore the complex data that was generated in this research. An example of a research participant’s annotated display from this data management and visualization tool is then presented. It is our view that this tool provides the capacity to better visualize and understand the complex data relationships that may arise in VR research that investigates naturalistic free will behavior and its impact on other human performance variables.     

The "bright spot of consciousness"

I.P. Pavlov considered consciousness as an area of optimum excitability moving over the human cerebral cortex depending on the character of performed mental activity. Contemporary methods of computer analysis of electrical activity and brain thermal production have allowed to turn this metaphor into experimentally observed reality. It is shown that preservation of connections of cortical gnostic zones with verbal structures of the left hemisphere is the obligatory condition for consciousness functioning. These data reinforce the determination of consciousness as operation with knowledge, which by means of words, mathematic symbols and art images can be transmitted to other people. Communicative origin of consciousness creates possibility of mental dialogue with oneself, i.e. leads to the appearance of self-consciousness of the personality.     

Personal Meaning and the Transformation of a Mental Image

It is generally accepted that the reflection of reality in human consciousness is by no means an exact photographic reproduction of reality. "An image is the reflection of an object, and an object is reflected in an image in just the same guise as it exists in the real life relation between it and the subject" (Rubinshtein, 1957. P. 230). Thus, an element of personal, subjective partiality, the reflection of not only phenomena or objective relations themselves but also of their meaning for the person and their relation to his needs (Rubinshtein, 1959. P. 124; Leont'ev, 1977; Vilyunas, 1983; etc.), is necessarily present in a mental image. Personal meaning is also a component of individual consciousness; in it the partiality of that consciousness finds expression, a partiality conditioned by the link between that consciousness and the subject's need and motivational sphere and the reality of his life in the world (Leont'ev, 1977. Pp. 152-53). The objects and phenomena of reality are presented to us in direct perception and in our imagination in a form that is "colored" by the personal meaning they have for us as a result of their objective place in our life activity and their relation to the realization of our needs. It is not always possible to differentiate between objective content and personal relation even in reflection. Often, the meaning of an object cannot be separated from the object itself and examined impartially, from the sidelines, so to speak. This is most patently in evidence in the example of one's perception of other people, especially those who are very familiar.     

The Biology of Time and Death

The steady flow of solar energy through prebiotic chemical systems forced them to undergo material cycles, and this cycling was inherited by living organisms. Organisms whose cycling synchronized with periodic phenomena, such as day/night and seasonal variations were favored. At a later stage, evolution also favored organisms that, besides of a synchronized cycling, developed a 'sense of time' to cope with non-cyclic and unique events in the environment. In the case of human beings, this 'sense of time' was used to detect causal chains (cause → effect), combine them to produce dynamic models of reality, and transform real time scales into mental time scales (it takes a moment to remember a year-long phenomenon). The 'sense of time' constituted a decisive evolutive advantage, because it enables humans to analyze a multitude of future possibilities, and choose the most promising one. Yet 'sense of time' is just an empty metaphore, because it is not a true 'sense', and we ignore what 'time' really is. Most scientific disciplines simply take for granted that there is a 'time flowing from future to past'. Biologists instead, cannot adopt this attitude because 'time' may very well be an intrinsic property of our mind, i.e., a peculiar aspect of brain physiology.     

Advances in Brain Research

Current study of the brain has reached a stage where the researcher in this field realizes that he is only just beginning to unravel the secrets of the brain. It is becoming increasingly clear that even the most significant physiological principles of nervous activity discovered so far are merely the portals of a hitherto little-known world of molecular processes that play a decisive role in the working of the brain.     

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.     

The evolution of the human mind and logic--mathematics structures

The evolution of the human mind is discussed based on: (i) the fact that living beings interchange matter, energy and information with their environment, (ii) an ontological interpretation of the "reality" of the quantum world, of which logic-mathematics structures are considered constitutive parts, (iii) recent theories according to which living beings are considered as dynamic complex systems organized by information, and (iv) the fact that the evolution of living beings is guided by information about the environment and by intrinsic information on living systems (auto-organization). Assuming the evolution of vision as a model we observe that the driving forces that directed the evolution of the eyes, as dynamic complex systems, are the information about the environment supplied by sunlight and the intrinsic information-gaining mechanism of living organisms. Thus, there exists a convergence toward a visual system with the greatest ability to obtain light information, like the human eye, and also a divergence that leads to the development of specific qualities in some species. As in the case of vision the evolution of the human mind-brain cannot be a consequence of factors unrelated to the object of its own functioning. The human mind was structured for the acquisition from reality of the logic-mathematics structures that underlie the whole universe and consequently of an internal representation of the external world and of its own self. Thus, these structures are, together with the intrinsic capacity for auto-organization of the human brain, the predominant driving force of the human mind evolution. Both factors are complementary.     

Magnetic correlates in electromagnetic consciousness

ABSTRACT

We examine the hypothesis that consciousness is a manifestation of the electromagnetic field, finding supportive factors not previously considered. It is not likely that traditional electrophysiological signaling modes can be readily transmitted throughout the brain to properly enable this field because of electric field screening arising from the ubiquitous distribution of high dielectric lipid membranes, a problem that vanishes for low-frequency magnetic fields. Many reports over the last few decades have provided evidence that living tissue is robustly sensitive to ultrasmall (1–100 nT) ELF magnetic fields overlapping the γ-frequency range often associated with awareness. An example taken from animal behavior (coherent bird flocking) lends support to the possibility of a disembodied electromagnetic consciousness. In contrast to quantum consciousness hypotheses, the present approach is open to experimental trial.     

The Biology of Time and Death

The steady flow of solar energy through prebiotic chemical systems forced them to undergo material cycles, and this cycling was inherited by living organisms. Organisms whose cycling synchronized with periodic phenomena, such as day/night and seasonal variations were favored. At a later stage, evolution also favored organisms that, besides of a synchronized cycling, developed a ‘sense of time’ to cope with non-cyclic and unique events in the environment. In the case of human beings, this ‘sense of time’ was used to detect causal chains (cause → effect), combine them to produce dynamic models of reality, and transform real time scales into mental time scales (it takes a moment to remember a year-long phenomenon). The ‘sense of time’ constituted a decisive evolutive advantage, because it enables humans to analyze a multitude of future possibilities, and choose the most promising one. Yet ‘sense of time’ is just an empty metaphore, because it is not a true ‘sense’, and we ignore what ‘time’ really is. Most scientific disciplines simply take for granted that there is a ‘time flowing from future to past’. Biologists instead, cannot adopt this attitude because ‘time’ may very well be an intrinsic property of our mind, i.e., a peculiar aspect of brain physiology.     

Endpiece: It works in every country

ObjectivesTo determine whether any vital signs can be used to quickly identify brain lesions in patients with impaired consciousness. DesignCross sectional observational study.SettingEmergency department of an urban hospital, Japan.Participants529 consecutive patients (mean age 65 years) presenting with impaired consciousness (score <15 on the Glasgow coma scale) during 2000.Results312 (59%) had a brain lesion which accounted for the impaired consciousness. The area under the receiver operating curve for systolic blood pressure was 0.90 (SE 0.01), indicating significantly higher accuracy (P<0.01) in the identification of a brain lesion than using diastolic pressure 0.82 (0.02) or pulse rate 0.63 (0.03). Likelihood ratios for systolic blood pressure lower than 90 mm Hg were less than 0.04, and those for systolic pressure higher than 170 mm Hg were greater than 6.09.ConclusionsSystolic blood pressure is useful for diagnosing brain lesions in patients with impaired consciousness.

What is already known on this topic

Brain imaging and neurological examination of patients with impaired consciousness are often a waste of time and resources and can delay correct diagnosis

What this paper adds

Systolic blood pressure distinguishes patients with impaired consciousness who are at high risk from those who are at low risk of an organic brain lesionGeneral use of systolic blood pressure in the diagnosis of impaired consciousness may have clinical and economic benefits