镜像神经在药物心理渴求中的作用及机制

心理渴求是物质依赖者希望重新感受神经活性药物效应的渴望,其神经机制的早期影像研究,主要集中在前额皮质和奖赏中枢.镜像神经是新近发现的位于动作脑区,能理解、分析所观察动作的目的和性质,并通过内隐模拟,产生直接映射式的情绪和认知的神经.最新的研究发现尼古丁成瘾者在相关线索的刺激下,其镜像神经也能被激活.本研究旨在探索镜像神经参与相关线索下心理渴求形成的机制,为发展更可靠的依赖行为的生物学标记提供另一个重要目标,帮助人们更好地理解药物渴求形成的神经生物学基础与过程.     

感知觉-运动系统在药物相关线索反应中的作用及神经机制

药物相关线索反应是成瘾行为的重要标志,它直接导致心理渴求和强迫性的刺激-反应式自动化用药行为。其神经机制是包含了经典和操作条件反射的联结学习。在联结过程中,除奖赏系统外,感觉-动作系统在相关线索反应中也起到了重要作用。其机理可能是与感觉运动脑区部分重合的镜像神经的理解、分析和推测动作意图目的以及内隐模仿的功能有关。另外,动作记忆的形成及功能也可能在这种自动化动作图式的形成中起到了重要的作用。其确切的机制需要进一步研究证据。     

用药动作线索诱发海洛因戒断者的镜像神经活动:一项fMRI研究

相关线索能够诱发药物依赖者的心理渴求,而健康人不会对相关线索产生心理渴求。15名海洛因成瘾者和12名没有任何物质滥用的健康被试参与实验,收集了他们在观看相关线索与对照线索时的脑神经活动。结果发现,药物线索能够诱发戒断者更多脑区的活动,包括扣带回和楔前叶。两组被试在对照动作线索刺激诱发作用下,其颞叶、顶叶均出现了较为一致的活动。在用药动作线索诱发作用下,戒断组双侧颞中回、双侧顶下小叶、左侧顶上小叶和右侧额下回显示出显著活动,并且与对照动作线索激活脑区一致;健康组被试除枕叶-颞叶联合区外,没有出现显著的脑区活动。以上结果表明,用药动作线索诱发了海洛因戒断者颞中回、顶下小叶、额下回等镜像神经系统的活动,这些脑区对不同类型的相关线索十分敏感,它们可能通过对用药动作的心理模拟,参与了用药动作线索的快速自动化加工。     

不同药物相关线索反应下感觉-运动脑区的激活及作用

药物相关线索反应不仅表现在心理渴求, 也表现在强迫性用药行为上。相关线索下, 除包括奖赏环路在内的边缘系统被激活外, 感觉-运动脑区也被激活, 引发自动化动作图式的表达, 这对相关线索反应及复吸行为具有特殊的意义。是否所有相关线索都会激活感觉-运动脑区, 目前, 还不清楚, 而这对临床治疗具有重要意义。本研究采用磁共振扫描, 生理测试等方法探索了不同类型相关线索下, 海洛因成瘾戒断者的大脑激活状况, 试图了解他们在不同线索刺激下的大脑反应。采用组内实验设计, 测量29名海洛因成瘾者相关线索反应下的血氧水平。结果发现, 相比对照线索, 所有药物相关线索, 包括药物、用药工具、用药动作线索都更多激活扣带回、海马、舌回、梭回等与奖赏机制相关的脑区; 而不同类型的药物相关线索之间的比较则显示, 用药工具和用药动作线索更多激活了双侧颞中回、双侧顶下小叶、左侧顶上小叶和右侧额下回等感觉-运动脑区。用药动作线索比单纯药物和用药工具线索, 激活了更为广泛的动作脑区。由此, 我们认为药物相关线索导致成瘾者大脑中奖赏和感觉-动作两套系统被激活, 包含用药工具、用药动作在内的相关线索会激活更多的感觉-运动脑区。     

基于“相关线索-自动化用药行为”联结的成瘾记忆消退

成瘾记忆消退致力于消除成瘾者相关线索与药物奖赏效应的联结,以达到消除心理渴求、戒断成瘾行为的目的,但其效果还十分有限。最近,大量的动物和人类实验研究发现:在相关线索下,成瘾者的激活脑区不仅包括中脑边缘皮层-背内侧纹状体,还延伸到感觉运动脑区-背外侧纹状体。这意味着成瘾记忆中存在相关线索与自动化(习惯性)用药行为的联结。所以,与成瘾相关的记忆可能包含两种不同的成分:一是与药物奖赏效应相关的情绪记忆,另一种是与用药动作、技能有关的动作记忆(程序记忆)。由于在成瘾阶段,药物奖赏效应对药物使用和复发的作用已经相对减少,因此,针对成瘾记忆的消退训练,以相关线索与自动化用药行为的联结为标靶,可能可以取得更好的效果,值得做进一步的深入探索。     

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     

宽恕心理的行为测量及认知神经机制

宽恕是一个复杂的心理过程,被认为是对冒犯者的亲社会化转变的过程,包括认知、情绪、动机和行为上的改变。本文回顾了国内外宽恕心理的行为测量范式和认知神经机制研究相关的成果,发现宽恕心理的行为测量范式能够揭示宽恕相关的心理过程;认知神经机制的研究发现宽恕心理过程主要涉及负责社会认知、共情和认知控制等功能的脑区。未来的研究应关注宽恕心理行为测量范式的有效性和揭示内容的一致性、宽恕心理的认知和脑神经基础。     

口香糖咀嚼的脑机制

该研究采用功能性核磁共振(fMRI)技术,考察了咀嚼口香糖时大脑的活动。结果发现,与休息相比,口香糖咀嚼显著增加了脑的BOLD(血氧依赖水平)信号;与口香糖咀嚼相关的脑区有初级运动皮层,右侧后顶叶,双侧小脑,以及双侧前额叶的部分区域。ROI(感兴趣区域)分析发现,咀嚼时不同脑区的对血氧含量有不同程度的提高,其中中央前回的血氧依赖水平信号变化量高达46.3%,说明口香糖咀嚼增强了某些脑区的活动,显著提高了这些脑区的血流和供氧水平。     

Mirror neurons, the representation of word meaning, and the foot of the third left frontal convolution

Previous neuroimaging research has attempted to demonstrate a preferential involvement of the human mirror neuron system (MNS) in the comprehension of effector-related action word (verb) meanings. These studies have assumed that Broca's area (or Brodmann's area 44) is the homologue of a monkey premotor area (F5) containing mouth and hand mirror neurons, and that action word meanings are shared with the mirror system due to a proposed link between speech and gestural communication. In an fMRI experiment, we investigated whether Broca's area shows mirror activity solely for effectors implicated in the MNS. Next, we examined the responses of empirically determined mirror areas during a language perception task comprising effector-specific action words, unrelated words and nonwords. We found overlapping activity for observation and execution of actions with all effectors studied, i.e., including the foot, despite there being no evidence of foot mirror neurons in the monkey or human brain. These "mirror" areas showed equivalent responses for action words, unrelated words and nonwords, with all of these stimuli showing increased responses relative to visual character strings. Our results support alternative explanations attributing mirror activity in Broca's area to covert verbalisation or hierarchical linearisation, and provide no evidence that the MNS makes a preferential contribution to comprehending action word meanings.     

情绪识别研究中被“冷落”的线索:躯体表情加工的特点、神经基础及加工机制

躯体和面孔是个体情绪表达与识别的重要线索。与面部表情相比,躯体表情加工的显著特点是补偿情绪信息,感知运动与行为信息,及产生适应性行为。情绪躯体与面孔加工的神经基础可能相邻或部分重合,但也存在分离;EBA、FBA、SPL、IPL等是与躯体表情加工相关的特异性脑区。今后应系统研究面孔、躯体及语音情绪线索加工潜在的神经基础,探讨躯体情绪加工的跨文化差异,考察情绪障碍患者的躯体表情加工特点。     

从“变色龙效应”到“镜像神经元”再到“模仿过多症”—— 作为社会交流产物的人类无意识模仿

人类无意识模仿是指人们在社会交流时会相互无意识地模仿对方的一些动作、表情和行为方式。其在个体社会认知以及人际交流上扮演着重要的角色。通过回顾近十年来人类无意识模仿的各个领域内的研究进展, 以及分析无意识模仿的行为学效应, 脑神经机制以及病理学调控, 可以得出如下结论：所有神经层面以及行为层面的人类无意识模仿现象都是社会交流的产物。该观点在澄清无意识模仿神经机制以及促进幼儿社会认知发展方面具有一定启示意义, 而探索孤独症患者无意识模仿障碍的病理机制有望为该领域的未来研究开启新的方向。     

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。     

Emulation and mimicry for social interaction: a theoretical approach to imitation in autism

The "broken-mirror" theory of autism argues that dysfunction of the "mirror neuron system" is a root cause of social disability in autism. The present paper aims to scrutinize this theory and, when it breaks down, to provide an alternative. Current evidence suggests that children with autism are able to understand and emulate goal-directed actions, but may have specific impairments in automatic mimicry of actions without goals. These data are not compatible with the broken-mirror theory, but can be accounted for by a new model called EP-M. The EP-M model segments the mirror neuron system into an indirect, parietal route for goal emulation and planning (EP) and a direct occipital-frontal route for mimicry (M). This fractionation is consistent with neuroimaging and behavioural studies of the mirror neuron system in typical children and adults. I suggest that top-down modulation of the direct M route may be dysfunctional in individuals with autism, leading to abnormal behaviours on mimicry tasks as well as other social disabilities.     

From monkey-like action recognition to human language: an evolutionary framework for neurolinguistics

The article analyzes the neural and functional grounding of language skills as well as their emergence in hominid evolution, hypothesizing stages leading from abilities known to exist in monkeys and apes and presumed to exist in our hominid ancestors right through to modern spoken and signed languages. The starting point is the observation that both premotor area F5 in monkeys and Broca's area in humans contain a "mirror system" active for both execution and observation of manual actions, and that F5 and Broca's area are homologous brain regions. This grounded the mirror system hypothesis of Rizzolatti and Arbib (1998) which offers the mirror system for grasping as a key neural "missing link" between the abilities of our nonhuman ancestors of 20 million years ago and modern human language, with manual gestures rather than a system for vocal communication providing the initial seed for this evolutionary process. The present article, however, goes "beyond the mirror" to offer hypotheses on evolutionary changes within and outside the mirror systems which may have occurred to equip Homo sapiens with a language-ready brain. Crucial to the early stages of this progression is the mirror system for grasping and its extension to permit imitation. Imitation is seen as evolving via a so-called simple system such as that found in chimpanzees (which allows imitation of complex "object-oriented" sequences but only as the result of extensive practice) to a so-called complex system found in humans (which allows rapid imitation even of complex sequences, under appropriate conditions) which supports pantomime. This is hypothesized to have provided the substrate for the development of protosign, a combinatorially open repertoire of manual gestures, which then provides the scaffolding for the emergence of protospeech (which thus owes little to nonhuman vocalizations), with protosign and protospeech then developing in an expanding spiral. It is argued that these stages involve biological evolution of both brain and body. By contrast, it is argued that the progression from protosign and protospeech to languages with full-blown syntax and compositional semantics was a historical phenomenon in the development of Homo sapiens, involving few if any further biological changes.     

Evidence for a distributed hierarchy of action representation in the brain

Complex human behavior is organized around temporally distal outcomes. Behavioral studies based on tasks such as normal prehension, multi-step object use and imitation establish the existence of relative hierarchies of motor control. The retrieval errors in apraxia also support the notion of a hierarchical model for representing action in the brain. In this review, three functional brain imaging studies of action observation using the method of repetition suppression are used to identify a putative neural architecture that supports action understanding at the level of kinematics, object centered goals and ultimately, motor outcomes. These results, based on observation, may match a similar functional-anatomic hierarchy for action planning and execution. If this is true, then the findings support a functional-anatomic model that is distributed across a set of interconnected brain areas that are differentially recruited for different aspects of goal-oriented behavior, rather than a homogeneous mirror neuron system for organizing and understanding all behavior.