镜像神经元是认知科学的“圣杯”吗?

镜像神经元作为近二十年来神经科学领域内最重要的发现之一,相关的一系列研究掀起了一场"理解社会行为的革命"。然而,通过系统考察镜像神经元最初的操作性定义、基本功能及其实验证据,发现许多研究者对于镜像神经元的定义存在误解,人类脑中是否存在镜像神经元及其功能依然是当前学术界的争议焦点。迄今仍然缺乏令人信服的证据表明镜像神经元(或系统)就是动作理解、动作模仿、共情以及读心的直接神经机制。因此,将镜像神经元视为"认知科学的圣杯"的主张是一种落后的模块论意识形态,只能催生新的"神经神话"。     

镜像神经元的意义

镜像神经元是一种感觉–运动神经元。它的典型特征是在动作观察和动作执行两个阶段皆被激活。多年来, 由于研究伦理的限制, 研究恒河猴时使用的单细胞电极植入方式无法应用于人类, 因而不能确定人类大脑皮层是否也存在着具有同样功能的神经细胞。但是通过脑成像技术, 神经科学家确定人类大脑皮层存在着具有相同或类似功能的脑区, 称为“镜像神经系统”。文章对镜像神经元及其人类镜像神经系统的意义进行了深入分析, 指出：(1)由于镜像机制把动作知觉和动作执行进行匹配, 观察者仅仅通过他人行为的知觉, 就激活了执行这一动作的神经环路, 产生了一种他人动作的具身模拟, 因而可以直接把握他人的行为意图; (2)镜像神经元所表现出来的那种动作知觉与动作执行的双重激活功能支持了身心一体说, 从方法论上证明了身心二元论的缺陷, 为身心的整体观提供了神经生物学的证据; (3)镜像神经机制把他人的动作与自己的运动系统相匹配, 以自身动作的神经环路对他人的动作做出回应, 促进了人际理解和沟通, 成为社会沟通的“神经桥梁”。     

镜像神经元系统的研究回顾及展望

镜像神经元系统的发现使得研究者从一个较为统一的神经机制层面了解人类多个层次的社会认知活动。在猕猴大脑F5区发现的镜像神经元可以在抽象的层面上帮助猕猴理解他人行为的意图。利用脑成像技术,研究发现人类的镜像神经元系统能够匹配外界的知觉表征和内在的动作表征从而通过“居身模仿”这一过程来进行模仿、语言理解、理解他人的意图及情绪这些重要的社会认知活动。另外,镜像神经元系统在社会交往中也起着重要作用,最后,就镜像神经元系统在心理理论中的作用、了解自我-他人问题和镜像神经元系统的关系、动机、经验等因素对镜像神经元系统活动的调控等问题对未来的研究方向进行了展望     

“镜像”的内涵与外延:围绕镜像神经元的争议

镜像神经元被认为是改变认知神经科学的重要发现,它的发现为迄今为止许多行为实验难以检验的心智或认知现象提供了一个统一的研究视角。然而,镜像神经元在社会认知活动中的重要作用却引起了研究者的激烈争论。系统回顾镜像神经元研究中的争议,可以尝试以争论焦点出现的逻辑关系和性质为依据将其划分为两类:一类是关于镜像"内涵"的争议,主要包括镜像神经元是否存在及其起源的争议。另一类则主要围绕镜像"外延"的争议,即有关镜像神经元系统和镜像机制的争议。未来的研究必须摒弃将镜像神经元视为"认知科学圣杯"的神经还原主义倾向,将之视为一个由多个子系统组成的开放的复杂巨系统,并将焦点转向关注镜像机制。     

重解动作理解的“戈尔迪之结”:镜像神经元祛魅

"动作理解"一直被视为镜像神经元功能最为保守的假设,同时也是证据链最为强健的领域之一,但其概念内涵却始终如同古希腊神话中的"戈尔迪之结"一般没有得到厘清。目前,动作理解的紧缩解释正在面临严峻的挑战。来自实验室检验与哲学拷问的证据倾向于认为,镜像神经元活动构成动作理解的观点是一种"循环论证",前者至多只能算作产生动作理解的附带原因,而不是必要与充分原因。将广义的动作分成运动、运动动作与运动动作链可以有效地澄清实现理解不同层次的动作需要具备哪些条件。回应质疑并为辩护自身立场指明前进方向,是重解动作理解"戈尔迪之结"的起点,将对镜像神经元的科学祛魅产生奠基性的影响。     

动允直接知觉的共鸣原理

传统认知理论认为我们只能间接知觉动允,而生态认知心理学则认为对动允的知觉是个体与环境信息直接共鸣的过程。生态认知心理学首先判定动允并不是存在于我们头脑中的认识,而是实际存在于个体-环境系统中的事实,对动允的直接知觉就是对动允的检测而非推测,是对动允信息的拾取而非对记忆内容的提取。这种直接知觉表现为身体的相关动作机制（动作神经元、肌肉组织等）与环境中动允信息的共鸣。进化与学习在共鸣的形成与发展中具有重要作用。     

镜像神经元的发现及其对身心二元论的超越

镜像神经元是意大利帕尔玛大学Rizzolatti等人在恒河猴大脑腹侧运动前皮层F5区发现的一种神经元。这种神经元在猴子操作和观察同一个指向某种目标的动作时(如伸手抓食物)皆被激活,似乎这种神经元映射了其它个体的动作,因此被命名为“镜像神经元”。镜像神经元通过具身的模拟把动作的执行和动作的知觉结合在一起,把观察过程与身体运动过程相融合,克服了二元论在身心之间所设置的障碍,为人们正确认识身心关系开辟了新的视角。     

心灵如何被感知:从松果体到镜像神经元

文章从笛卡尔的身心交感论开始,探讨了松果体在身心交互中的重要地位,并分心理主义、行为主义、认知主义三个阶段,描述了心理学回答"心灵如何被感知"的两条途径:心灵内省与行为反映。最后,文章特别描述了新近发现的镜像神经元,认为它可能是当代心理学体系内的"笛卡尔式松果体",是沟通身体活动与心理状态、自我与他人心理状态的桥梁。未来,镜像神经元在心理学研究中的地位,可能与松果体在笛卡尔体系内的地位一样重要。     

“动手不动口”：手部动作与语言进化的关系

语言进化是进化心理学研究领域的重要问题。镜像系统假说、工具制造假说与传授假说从不同角度对手部动作与语言进化间的关系进行了解释, 三种假说都认为人类语言起源于手部动作经验。相关实证研究发现：手语与口语具有一致性特征、语言与手部动作具有共同的神经基础、手势发展可以预测语言发展水平以及手势可以提高工具制造知识的传播效率, 这些研究为三种假说的具体观点提供了实证支持。未来该领域的研究需要关注手势语与口语在进化中的发展关系, 以及人类语言进化与其他认知特征的进化关系。     

动作理解因境而异:动作加工中情境信息的自动整合

针对动作理解的机制,模拟论主张大脑自发模拟他人的动作,就相同的动作其理解也相同,而理论论则认为人们基于合理性原则对他人动作进行推理,相同的动作发生在不同的情境时会有不同的理解。但以往研究所采用动作材料的运动学特性和发生情境存在共变,其难以区分动作理解是支持模拟论还是理论论。通过两项实验,采用动画制作技术来产生有无约束情境下的追逐动作,以指示动作加工过程的脑电μ抑制为指标,对前述两种观点进行了检验。其中,在约束情境中存在障碍物,追逐者需改变运动方向以绕过障碍物,从后方逐渐趋近目标;而无约束情境中不存在障碍物,但追逐者依然保持与存在约束情景下相同的运动模式。结果发现,当追逐动作发生在存在约束的情境时,其基于合理性原则推测可获得清晰的动作目标,该条件下的μ抑制程度高于不存在约束情境的条件(实验1);而当仅追逐者运动,即趋近的目标不确定时,虽然有约束和无约束情境间的物理差异与实验1相同,但条件间μ抑制的差异消失(实验2);且上述μ抑制并非与注意相关的枕叶α活动的泛化。该结果提示,动作发生的情境信息影响人们对动作的理解,即基于推理过程理解动作,支持理论论观点。     

Mirror neurons are not evidence for the Simulation Theory

Recently, there as been a resurgence of interest in theories of mindreading. New discoveries in neuroscience have revitalized the languishing debate. The discovery of so-called mirror neurons has revived interest particularly in the Simulation Theory (ST) of mindreading. Both ST proponents and theorists studying mirror neurons have argued that mirror neurons are strong evidence in favor of ST over Theory Theory (TT). In this paper I argue against the prevailing view that mirror neurons are evidence for the ST of mindreading. My view is that on an appropriate construal of their function, mirror neurons do not operate like simulation theorists claim. In fact, mirror neurons are more appropriately understood as one element in an information-rich mindreading process. As such, mirror neurons fit in better with some sort of TT account of mindreading. I offer a positive account, the Model TT, which better explains the role of mirror neurons in social cognition.     

Toward the Language-Ready Brain: Biological Evolution and Primate Comparisons

The approach to language evolution suggested here focuses on three questions: How did the human brain evolve so that humans can develop, use, and acquire languages? How can the evolutionary quest be informed by studying brain, behavior, and social interaction in monkeys, apes, and humans? How can computational modeling advance these studies? I hypothesize that the brain is language ready in that the earliest humans had protolanguages but not languages (i.e., communication systems endowed with rich and open-ended lexicons and grammars supporting a compositional semantics), and that it took cultural evolution to yield societies (a cultural constructed niche) in which language-ready brains could become language-using brains. The mirror system hypothesis is a well-developed example of this approach, but I offer it here not as a closed theory but as an evolving framework for the development and analysis of conflicting subhypotheses in the hope of their eventual integration. I also stress that computational modeling helps us understand the evolving role of mirror neurons, not in and of themselves, but only in their interaction with systems “beyond the mirror.” Because a theory of evolution needs a clear characterization of what it is that evolved, I also outline ideas for research in neurolinguistics to complement studies of the evolution of the language-ready brain. A clear challenge is to go beyond models of speech comprehension to include sign language and models of production, and to link language to visuomotor interaction with the physical and social world.     

Understanding intentions from actions: Direct perception,inference, and the roles of mirror and mentalizing systems

This review asks whether observers can obtain information about others’ intentions from observation of their actions; and if so, whether this process is performed using direct perceptual or inferential processes (prominent examples of each being the intention understanding theory of mirror neuron function, and mentalizing accounts of intention understanding, respectively). I propose four conditions that should be fulfilled in order to support a direct perception account, and suggest that only two of these conditions are supported by the existing data. I then propose and review three further sources of evidence which have the potential to inform this debate, concluding that the data do not support the direct perception account. In particular, mirror neurons may be involved in lower-level processes of action perception, but there is no evidence to support their involvement in the type of higher-level intention understanding that is proposed by the direct perception account.     

The etiology of specific fears and phobias in children: a critique of the non-associative account

The non-associative account of phobic etiology assumes that a number of specific fears (e.g., fear of heights, water, spiders, strangers, and separation) have an evolutionary background and may occur in the absence of learning experiences (e.g., conditioning). By this view, these specific fears pertain to stimuli that once posed a challenge to the survival of our prehistoric ancestors. Accordingly, they would emerge spontaneously during the course of normal development and only in a minority of individuals, these specific fears would persist into adulthood. While the non-associative approach has generated interesting findings, several critical points can be raised. First, it capitalizes on negative findings, i.e., the failure to document learning experiences (e.g., conditioning, modeling) in the history of phobic children. Second, it largely ignores factors that have been found to be crucial for the acquisition of early childhood fears (e.g., the developmental level of the child, stimulus characteristics such as novelty, aversiveness, and unpredictability, and early experience with uncontrollable events). As an alternative to the non-associative account, we briefly describe a multifactorial model of childhood fears and phobias.     

Neurotheology and Evolutionary Theology: Reflections on the Mystical Mind

Eugene d'Aquili and Andrew B. Newberg in their book The Mystical Mind suggest that their neurotheology is both a metatheology and a megatheology. In this commentary I question whether neurotheology is comprehensive enough and suggest that it needs to and possibly can take into account the moral and social dimensions of religion. I then propose an alternative metatheology and megatheology: evolutionary theology grounded in the science of biocultural evolution and focusing on ultimate reality as creatively immanent in natural and human history. Neurotheology and evolutionary theology may complement one another. Evolutionary theology accounts for both the neurology of the brain and culturally evolved ideas and practices of particular religions and their theologies. Hence it seems more comprehensive than neurotheology. However, because ultimate reality in evolutionary theology is immanent in the world of space and time, of baseline experience, it cannot account for the mystic experience of absolute unitary being. In accounting for this transcendent experience and its reality, neurotheology is more comprehensive. However, neither theology can account for how transcendent ultimate reality, experienced by the mystic as absolute unitary being, gives rise to the changing world experienced as baseline reality.     

Social makes smart: rearing conditions affect learning and social behaviour in jumping spiders

There is a long-standing debate as to whether social or physical environmental aspects drive the evolution and development of cognitive abilities. Surprisingly few studies make use of developmental plasticity to compare the effects of these two domains during development on behaviour later in life. Here, we present rearing effects on the development of learning abilities and social behaviour in the jumping spider Marpissa muscosa. These spiders are ideally suited for this purpose because they possess the ability to learn and can be reared in groups but also in isolation without added stress. This is a critical but rarely met requirement for experimentally varying the social environment to test its impact on cognition. We split broods of spiders and reared them either in a physically or in a socially enriched environment. A third group kept under completely deprived conditions served as a ‘no-enrichment’ control. We tested the spiders’ learning abilities by using a modified T-maze. Social behaviour was investigated by confronting spiders with their own mirror image. Results show that spiders reared in groups outperform their conspecifics from the control, i.e. ‘no-enrichment’, group in both tasks. Physical enrichment did not lead to such an increased performance. We therefore tentatively suggest that growing up in contact with conspecifics induces the development of cognitive abilities in this species.     

Whose DAM account? Attentional learning explains Booth and Waxman

Booth and Waxman (Cognition 84 (2002) B11) have recently shown that linguistic cues to animacy affect children's novel name extensions. They argue that this demonstration contradicts two central tenets of our attentional learning account of object naming, which Booth and Waxman characterize as the "dumb attentional mechanism" or "DAM" account. In the present article, we show that the first of these tenets has never been a feature of the attentional learning account, and that the second tenet, which is central to our account, is not addressed by Booth and Waxman's findings. We suggest that the debate about the nature of children's language and cognition would profit from an increased awareness of the different levels of analysis at which different researchers are working.     

The development of Lewis Henry Morgan's evolutionism

Lewis Henry Morgan never used the term evolution in any of his major sociological works. If he may be labeled an evolutionist, the specificity of his views must be taken into account. The main "evolutionist" issue that concerned him was that of the unity or diversity of the human species. This was an urgent political and theological issue in the America of his day, and it impinged also on research on the American Indians. Morgan's first major study was designed to demonstrate the unity of origin of the American aborigines and their "Asian" origins. His methods were derived from the tradition of Indo-European philology. It was virtually as an afterthought that he added a social evolutionary component to what he conceived of as an exercise in philology. Later he came under the direct influence of the English evolutionists, and this was crucial for the conception of Ancient Society.