元认知的神经机制:元认知功能、脑区与脑网络

元认知是指个体对当前进行的认知活动的监测和调节。通过对元认知神经机制研究的梳理,归纳出两条研究主线:一条主线以具体元认知加工的脑区激活研究为主,主要考察元认知与认知过程的分离及典型元认知加工的共享性和特异性。研究发现元认知加工主要与前额叶有关,还涉及脑岛、顶叶、颞叶和楔前叶等部分脑区。另一条主线探讨广泛的元认知功能与广泛大脑网络的相关。研究提出了大脑的“元认知网络”的概念,发现脑损伤或病变造成的元认知功能损伤与脑功能网络有关,而非固定在某一特定脑区。建议未来的研究应重视四个方面的研究:元认知加工的具体脑区和脑功能网络,元认知神经机制的分离,元认知脑功能的损伤和元认知训练的改善作用,以及基于神经机制研究的元认知模型的建构与修正。     

正念冥想对情绪的调节作用:理论与神经机制

正念冥想可调节个体的负性情绪、促进个体正性情绪,对于心身疾病具有显著的干预效用.正念冥想的再感知模型、正念应对模型、推动性上升螺旋模型以及正念情绪调节模型都强调了正念冥想对情绪的调节作用.认知神经科学的研究发现,正念冥想可促进左侧前额叶脑区激活增强,涉及的脑区主要包括背外侧前额叶皮层(DLPFC)和背内侧前额叶皮层(DMPFC).研究者进一步发现,正念特质是通过改善前额叶对边缘系统反应的调节来实现对情绪的调节作用.而且,这种调节作用还有可能体现为通过冥想训练分离联结在一起的两种自我参照神经机制,从而加强体验性神经机制.另外,研究者还发现,正念冥想训练还可以改变与情绪加工相关的大脑结构.进一步澄清冥想训练与大脑偏侧化的关系和不同类型被试之间的比较研究将成为该领域日后研究的重点.     

社会两难情境下的合作选择:自我利益和集体利益间的权衡

社会两难是个人利益与集体利益冲突的情景。在这种情景下,合作选择强调个体是通过分享使集体利益最大化,而非个人利益最大化。"自我控制"、"信任"与"内疚厌恶"被用来阐述两难情境下合作选择的机制。而神经层面的研究也发现,合作选择主要涉及以背外侧前额叶皮层为主的执行控制脑区、以腹内侧前额叶为主的情绪调节脑区,以及包括纹状体、伏隔核和眶额叶等在内的奖赏相关脑区。未来研究需从完善研究方法和内容、深化内在机制以及整合合作决策的神经机制等几个方面着手。     

内疚的认知和情绪活动及其脑区调控

内疚是个体做出危害他人的行为或违反道德准则之后产生的良心上的反省, 对行为负有责任的一种负性体验。内疚在道德规范和人际社会中具有重要的作用。研究者主要采取自我报告范式、情境模拟范式、过失范式和经济博弈范式考察内疚的发生发展及其功能。近年来, 研究者尝试揭示内疚脑机制, 研究发现内疚主要激活前额叶皮层和脑岛等脑区, 前额叶可能与内疚的认知成分相关, 而脑岛主要与内疚的情绪成分相关。未来的研究需要采用多种技术手段进一步考察内疚的认知神经机制。     

内侧前额叶皮质—— “自我”的神经基础

自我神经基础的探讨常基于自我相关加工的研究, 涉及皮质中线结构各个脑区甚至全脑协同作用。内侧前额叶皮质及其次成分在自我相关加工中发挥重要作用：腹内侧前额叶皮质较多支持默认模式下的自我加工、自我信息的觉察和“在线”自我加工, 背内侧前额叶皮质主要参与有意识的自我参照加工、自我信息的评价和“主导的”自我加工。在自我-他人表征中, 自我-他人表征的情感性、认知性和文化性因素均调节内侧前额叶皮质及次成分的活动。未来在动态的时间和人际背景中解析自我加工的神经机制是重要的研究方向。     

应用动态因果模型研究阅读神经网络背、腹侧通路的协作机制

在神经网络的最新取向下, 探讨阅读脑机制中背侧和腹侧通路的协作机制, 是解决语言认知神经科学多个理论问题共同面临的焦点。本项目拟通过两个脑功能成像实验, 建构汉字阅读的动态因果模型, 系统地考察汉字阅读的神经网络, 以及阅读网络中背、腹侧通路的协作机制。实验一利用快速适应实验范式的优点, 识别和考察汉字阅读涉及的认知成分所对应的功能脑区, 以及脑区联结形成的神经回路, 并建构汉字阅读的动态因果模型; 实验二进一步考察在刺激属性(语音和语义信息)和任务要求下阅读脑区的动态激活及相互作用。通过不同任务下的模型对比, 重点探讨阅读网络的脑区联结模式变化, 尤其是背、腹侧通路受刺激和任务影响时的协作机制。研究结果将为揭示阅读的神经生理模型、解决语言特异性脑区激活的争论等理论问题提供直接的证据, 还能为语言教学、阅读障碍矫治、以及临床应用提供理论基础与指导。     

催产素影响恐惧习得和消退的认知神经机制

恐惧是一种基本的情绪, 在人类的生存和适应中发挥着重要作用。先前的研究表明, 杏仁核、背侧前扣带回、脑岛等脑区是条件化恐惧习得的认知神经基础, 杏仁核、海马和腹内侧前额叶等脑区在恐惧消退过程中发挥重要作用。研究发现, 催产素与恐惧习得和恐惧消退过程密切相关。恐惧习得过程中, 催产素影响杏仁核、背侧前扣带回的活动, 影响杏仁核与背侧前扣带回和脑干间的功能连接, 促进或抑制恐惧习得过程; 恐惧消退过程中, 催产素影响了杏仁核和腹内侧前额叶的活动, 并且影响杏仁核与内侧前额叶和海马间的功能连接, 促进或抑制恐惧消退过程。未来研究应从性别差异、神经网络模型、身心发育和病理研究等角度展开, 力图深入理解催产素影响恐惧情绪加工的认知神经机制。     

药物成瘾者决策缺陷的特征、机制及干预

药物成瘾者存在决策缺陷, 并表现出冲动性、风险寻求、奖赏失调、躯体内感信号缺失等特征。神经影像学研究表明药物滥用导致成瘾者背外侧前额皮层、前扣带回、眶额叶皮层、腹内侧前额皮层、杏仁核、脑岛等脑区受损, 这些损伤是引发其决策缺陷的主要原因。认知训练有利于提高个体的决策能力, 如目标管理训练和正念冥想等可以增强个体工作记忆、促进自我觉察和以目标为导向的行为; 而非侵入性脑刺激则可以直接改变与成瘾者决策相关脑区的激活状态, 从而提升与决策相关的认知功能。总体而言, 未来认知训练和非侵入性脑刺激在成瘾干预方面仍有广阔的拓展空间。     

自我和他人的协调与心理理论的神经机制

有关心理理论神经机制的研究远未达到共识。从自我与他人协调的角度看,可认为它是一个由多脑区有机组织而成的系统。自我中心化偏差是人类认知的一种默认选择,要正确理解他人的心理状态,需要抑制自我中心偏差。因此,心理理论的加工至少包括以下几个不同的过程：通过模拟自我理解他人,相应的加工脑区为镜像神经元系统;从他人与客体形成的二元关系中表征心理状态的内容,相应脑区是颞顶联合区;对模拟自我进行抑制,相应脑区为背外侧额叶;以及整合协调以上几个过程,其脑区可能是内侧前额叶     

经济决策中人际信任博弈的理论模型与脑机制

信任是指个体在缺乏足够信息来判断他人动机、意图和行为的情况下,将社会资源交给对方处置并承担相应风险的意愿。作为一种基本的社会信号机制,信任对于发展和维持良好社会关系具有重要作用。借助信任博弈范式,研究者揭示了人际信任的认知神经机制并建构了多种理论,包括背叛厌恶理论、社会规范理论、道德规范理论和默认行为模型。脑成像研究发现信任行为主要涉及内侧前额叶、尾状核、杏仁核和脑岛等脑区,其中内侧前额叶主要参与心理推理、情绪认知与调控等过程,尾状核参与同伴值得信赖性的习得与编码,杏仁核和脑岛则主要参与风险、不确定性和背叛恐惧加工。今后研究应侧重不同理论之间的补充与整合,强化不同脑区之间的功能连接与整体性,并注重信任行为中的个体差异。     

功能性近红外光谱技术在社会互动脑机制研究中的应用

功能性近红外光谱技术是一种以大脑组织中的血容和血氧为信息载体,通过测量大脑皮层中血容和血氧的分布和变化情况来了解局部脑活动的技术手段。近年来该技术在双脑研究非言语互动、言语互动、混合互动等社会互动脑机制领域做出了重要贡献。为了更清晰地揭示自然情境中社会互动的神经机制,未来尚需进一步改进近红外光谱技术本身,开发有效的数据分析方法,细化互动任务类型,丰富完善实验范式,促进多种脑成像技术的融合。     

The neuropsychology of ventral prefrontal cortex: decision-making and reversal learning

Converging evidence from human lesion, animal lesion, and human functional neuroimaging studies implicates overlapping neural circuitry in ventral prefrontal cortex in decision-making and reversal learning. The ascending 5-HT and dopamine neurotransmitter systems have a modulatory role in both processes. There is accumulating evidence that measures of decision-making and reversal learning may be useful as functional markers of ventral prefrontal cortex integrity in psychiatric and neurological disorders. Whilst existing measures of decision-making may have superior sensitivity, reversal learning may offer superior selectivity, particularly within prefrontal cortex. Effective decision-making on existing measures requires the ability to adapt behaviour on the basis of changes in emotional significance, and this may underlie the shared neural circuitry with reversal learning.     

面孔审美加工的神经机制及个体差异

外显和内隐的面孔审美加工的脑成像研究表明,美的面孔比不美的面孔导致眶额皮层、伏隔核、杏仁核等奖赏脑区更大的激活。脑电研究则发现了与面孔审美加工有关的早期负波和晚期正成分。面孔审美加工有关的脑区活动也受到性别、生理周期等个体因素的调节。未来的研究需要比较美的面孔与其它奖赏刺激加工的神经机制,探讨面孔审美加工的不同阶段及时间进程,在面孔知觉的框架下形成合理的面孔审美加工的神经模型。     

A model of amygdala–hippocampal–prefrontal interaction in fear conditioning and extinction in animals

Empirical research has shown that the amygdala, hippocampus, and ventromedial prefrontal cortex (vmPFC) are involved in fear conditioning. However, the functional contribution of each brain area and the nature of their interactions are not clearly understood. Here, we extend existing neural network models of the functional roles of the hippocampus in classical conditioning to include interactions with the amygdala and prefrontal cortex. We apply the model to fear conditioning, in which animals learn physiological (e.g. heart rate) and behavioral (e.g. freezing) responses to stimuli that have been paired with a highly aversive event (e.g. electrical shock). The key feature of our model is that learning of these conditioned responses in the central nucleus of the amygdala is modulated by two separate processes, one from basolateral amygdala and signaling a positive prediction error, and one from the vmPFC, via the intercalated cells of the amygdala, and signaling a negative prediction error. In addition, we propose that hippocampal input to both vmPFC and basolateral amygdala is essential for contextual modulation of fear acquisition and extinction. The model is sufficient to account for a body of data from various animal fear conditioning paradigms, including acquisition, extinction, reacquisition, and context specificity effects. Consistent with studies on lesioned animals, our model shows that damage to the vmPFC impairs extinction, while damage to the hippocampus impairs extinction in a different context (e.g., a different conditioning chamber from that used in initial training in animal experiments). We also discuss model limitations and predictions, including the effects of number of training trials on fear conditioning.     

自我控制失败的理论模型与神经基础

自我控制指那些帮助人们克服思想和情绪, 进而依据实际情况调整自我行为的心理加工。虽然良好的自我控制对个体的成功与幸福非常重要, 但自我控制失败仍然是整个人类社会的核心问题。借助于序列任务范式, 研究者揭示了自我控制失败的认知机制并建构了多种理论, 包括能量模型、加工模型、中央管理器模型和前额叶−皮层下脑区的平衡模型。相关脑成像研究主要聚焦于额下回、杏仁核、眶额叶皮质等脑区。未来研究应侧重不同理论之间的融合与补充, 强化自我控制失败潜在神经机制的探索, 并推动自我控制与社会决策行为的关系研究。     

Hierarchically organized behavior and its neural foundations: a reinforcement learning perspective

Research on human and animal behavior has long emphasized its hierarchical structure—the divisibility of ongoing behavior into discrete tasks, which are comprised of subtask sequences, which in turn are built of simple actions. The hierarchical structure of behavior has also been of enduring interest within neuroscience, where it has been widely considered to reflect prefrontal cortical functions. In this paper, we reexamine behavioral hierarchy and its neural substrates from the point of view of recent developments in computational reinforcement learning. Specifically, we consider a set of approaches known collectively as hierarchical reinforcement learning, which extend the reinforcement learning paradigm by allowing the learning agent to aggregate actions into reusable subroutines or skills. A close look at the components of hierarchical reinforcement learning suggests how they might map onto neural structures, in particular regions within the dorsolateral and orbital prefrontal cortex. It also suggests specific ways in which hierarchical reinforcement learning might provide a complement to existing psychological models of hierarchically structured behavior. A particularly important question that hierarchical reinforcement learning brings to the fore is that of how learning identifies new action routines that are likely to provide useful building blocks in solving a wide range of future problems. Here and at many other points, hierarchical reinforcement learning offers an appealing framework for investigating the computational and neural underpinnings of hierarchically structured behavior.     

Functional magnetic resonance imaging responses relate to differences in real-world social experience

Although neuroimaging techniques have proven powerful in assessing neural responses, little is known about whether scanner-based neural activity relates to real-world psychological experience. A joint functional magnetic resonance imaging (fMRI)/experience-sampling study investigated whether individual differences in neurocognitive reactivity to scanner-based social rejection related to: (a) moment-to-moment feelings of social rejection during real-world social interactions ("momentary social distress") and (b) the extent to which these momentary feelings corresponded with end-of-day global assessments of social disconnection ("end-of-day social disconnection"). Individuals who showed greater activity in regions associated with affective and pain processing (dorsal anterior cingulate cortex, amygdala, periaqueductal gray) during scanner-based social rejection reported feeling greater momentary social distress during their daily social interactions. In contrast, individuals who showed greater activity in regions associated with memory and self-referential memory encoding (hippocampus, medial prefrontal cortex) showed a stronger correspondence between momentary social distress and end-of-day social disconnection, such that greater momentary social distress was associated with greater end-of-day social disconnection. These findings complement previous work showing a dissociation between momentary and retrospective reports of affect and suggest that these processes rely on dissociable neural systems.     

Frontal-Lobe Involvement in Spatial Memory: Evidence from PET,fMRI, and Lesion Studies

Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.     

Value, pleasure and choice in the ventral prefrontal cortex

Rapid advances have recently been made in understanding how value-based decision-making processes are implemented in the brain. We integrate neuroeconomic and computational approaches with evidence on the neural correlates of value and experienced pleasure to describe how systems for valuation and decision-making are organized in the prefrontal cortex of humans and other primates. We show that the orbitofrontal and ventromedial prefrontal (VMPFC) cortices compute expected value, reward outcome and experienced pleasure for different stimuli on a common value scale. Attractor networks in VMPFC area 10 then implement categorical decision processes that transform value signals into a choice between the values, thereby guiding action. This synthesis of findings across fields provides a unifying perspective for the study of decision-making processes in the brain.     

主观价值计算与整合的神经机制及其影响因素

决策在人类社会发展的历程中扮演着非常重要的作用,而对其神经机制的探讨才不过几十年的时间。基于价值的决策理论,强调人们首先计算和表征事物的价值,随后比较和决策。在人脑中负责主观价值计算的神经基础有腹内侧前额叶皮层、眶额皮层以及其他脑区,而负责价值整合的脑区有腹内侧前额叶皮层、眶额皮层、背外侧前额叶皮层等。其中时间和风险的价值计算有着相同的神经基础,并且人脑可以将不同属性以及成本进行整合形成主观价值,按照曲线交互作用范式进行。通过自我控制、注意和认知调节等方法,同样可以调制人们的主观价值大小。未来需要继续强调模式分析、个体差异、老龄化和基因对价值计算的影响。