视觉注意的顶叶神经机制

大脑皮层后顶叶是联合皮层的一部分。它前界体感区,后接视纹前皮层。传统上认为,脑的某些将感觉传入、概念和思想等一些不同的活动的神经信号联合起来的脑区称联合皮层。它是神经整合的高级中枢。灵长类后顶叶联合区与视觉注意密切相关。近年来,美国威斯康星大学神经生理系Yin,T·C·T.及其共同工作者应用微电极技术结合行为指标,在清醒猴上,记录了视觉注意时后顶叶皮层单个神经元活动特征。他们发现,下顶叶(7区)有4类神经元与视觉注意有关,其中三类不是通常意义的感觉或运动神经元。这些神经元是在动物注视着关心的目标物时才活动。Yin等设想,下顶叶对来自两个不同来源的信号进行整合,     

价值观的神经机制:另一种研究视角

神经机制分析是价值观研究的一种新视角.内稳态机制和情绪反应的固有模式可能体现出价值观的神经生物原型.社会认知神经科学试图从子价值观、价值取向、价值观结构等方面寻找价值观的神经实体证据,也对价值评价、价值决策等相关过程进行了神经活动分析.初步发现了个体价值观与部分脑区活动的相关关系,涉及前额叶-顶叶-颞叶神经网络带的众多大脑结构.未来研究可沿循静态的价值观结构和动态的价值观加工过程两条线路,整合和完善现有分散的神经生理研究,将有助于更系统地理解价值观的神经机制.     

人类社会认知的神经机制:来自社会脑研究的证据

社会认知是指从环境互动的过程中推测他人意图、情感和思想等内部状态的心理加工过程。社会脑假说认为,包括人类在内的灵长类大脑内肯定存在着一个旨在认识和理解他人表情的神经机制,在社会交往中通过该中枢迅速处理与他人相互作用的各种信息。本文通过回顾社会脑的构成与基本功能,镜像神经元的发现及功能,以及社会脑、镜像神经元对社会认知影响的相关研究,提出了人类社会认知不同于其他物种的三个主要区别。     

事件相关振荡与振荡脑网络

事件相关振荡是伴随认知、情感和行为过程的脑电磁振荡活动,观察到其各类调频、调幅和调相现象,这种介观和宏观尺度上大量神经元的集体活动与微观尺度上神经元平均发放率和发放定时相互影响,共同参与神经信息的编码、表征、通讯和调控。动态细胞集群假说认为大脑认知功能是神经网络通过同步振荡相互作用的结果,在基于振荡的大脑理论指引下,多尺度、跨脑区和跨频率事件相关振荡研究为揭开振荡脑网络的工作原理带来了希望     

启动和重复抑制:启动神经机制的研究述评

启动是经验对当前任务的易化作用.重复抑制是刺激重复导致的皮层神经活动减少.大量研究表明启动与重复抑制密切相关.该文以理论假设对启动研究结果的解释效力为依据,对近期认知领域内有关启动和重复抑制的研究进行梳理,评介三种理论解释启动神经机制的适用性和局限性.指出未来研究可以考虑细化启动成分和重复抑制的具体关系,并尝试在此基础上建立神经元、重复抑制和行为启动的整合理论.这将对启动神经机制的理解具有重要意义.     

“脑的10年”与神经科学的发展(续)

5.发育神经生物学是神经科学又一重要研究领域 发育神经生物学对认识脑的结构与功能,探明神经系统疾病,有重要的理论与实践意义。脑是物质的,又是进化的。从个体发育来看,脑和身体的其它部分一起都是来自一个受精卵。神经发育这一极端复杂的事件是对发育生物学的最大挑战。发育神经生物学主要研究神经细胞的分化与神经线路的建立问题。神经系统的特性之一是各神经元群之间的精确而又有秩序的联结。脊椎动物中枢神经系统在神经管形成之后,至少经过增殖、移行、集合、轴突生长、膜和代谢发育、细胞死亡、突触发生、突触排除等一系列相互关系的过程。其中轴突寻找目标的活动及突触的发生和排除过程,是人们最感兴趣和研究最多的领域。神经元突起(特别是轴突)的形成是神经元分化的突出表现,它是按化学梯度和接触引导两种机制生     

对语言神经机制的新认识

本文针对语言神经机制的研究现状,分析了失语症和裂脑人研究的成果,并且较为详细地介绍了最近十年脑功能成像得到的有关语言神经活动的新成就,在此基础上,提出了一种动态分布式竞争的解释理论,用来解释语言神经活动现象和规律,并进一步借以说明言语意识的产生机制。     

空间导航的脑网络基础和调控机制

空间导航在生活中时刻发生,空间能力衰退是阿尔兹海默症的重要早期表现。早期关于空间导航神经机制的研究主要关注单个脑区的特异性功能,但这些脑区如何交互以整合不同模态的信息支持复杂导航行为尚不清楚。脑成像技术、脑网络建模方法和神经调控手段的发展,为在脑网络水平理解人类空间导航的认知神经机制提供了重要研究手段。本研究试图融合空间导航认知神经机制研究的最新进展,借助脑网络建模、大数据分析、微电流刺激等前沿研究手段,研究空间导航脑网络的关键拓扑属性特征(如模块化、核心节点等),探寻该功能特异性神经网络的重要影响因素和调控机制,并构建空间导航的脑网络理论模型。研究成果将有利于理解人类复杂导航行为的脑网络基础,为阿尔兹海默症等相关认知障碍脑疾病的筛查和诊断提供重要参考。     

短时记忆与长时记忆的神经机制

透过脑、神经元、突触以及记忆的分子机制,利用脑功能成像等方法来探讨区分短时记忆与长时记忆的神经机制。其主要观点是:记忆有着相似的突触和分子机制;其储存部位主要在脑区的新皮层区,如:颞、顶、枕叶新皮层;并阐述有关分离短时记忆与长时记忆的神经科学证据。     

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     

Complexity and coherency: integrating information in the brain

The brains of higher mammals are extraordinary integrative devices. Signals from large numbers of functionally specialized groups of neurons distributed over many brain regions are integrated to generate a coherent, multimodal scene. Signals from the environment are integrated with ongoing, patterned neural activity that provides them with a meaningful context. We review recent advances in neurophysiology and neuroimaging that are beginning to reveal the neural mechanisms of integration. In addition, we discuss concepts and measures derived from information theory that lend a theoretical basis to the notion of complexity as integration of information and suggest new experimental tests of these concepts.     

视听跨通道信息的整合与冲突控制

多通道信息交互是指来自某个感觉通道的信息与另一感觉通道的信息相互作用、相互影响的一系列加工过程。主要包括两个方面：一是不同感觉通道的输入如何整合;二是跨通道信息的冲突控制。本文综述了视听跨通道信息整合与冲突控制的行为心理机制和神经机制,探讨了注意对视听信息整合与冲突控制的影响。未来需探究视听跨通道信息加工的脑网络机制,考察特殊群体的跨通道整合和冲突控制以帮助揭示其认知和社会功能障碍的机制。     

Temporal binding, binocular rivalry, and consciousness.

Cognitive functions like perception, memory, language, or consciousness are based on highly parallel and distributed information processing by the brain. One of the major unresolved questions is how information can be integrated and how coherent representational states can be established in the distributed neuronal systems subserving these functions. It has been suggested that this so-called "binding problem" may be solved in the temporal domain. The hypothesis is that synchronization of neuronal discharges can serve for the integration of distributed neurons into cell assemblies and that this process may underlie the selection of perceptually and behaviorally relevant information. As we intend to show here, this temporal binding hypothesis has implications for the search of the neural correlate of consciousness. We review experimental results, mainly obtained in the visual system, which support the notion of temporal binding. In particular, we discuss recent experiments on the neural mechanisms of binocular rivalry which suggest that appropriate synchronization among cortical neurons may be one of the necessary conditions for the buildup of perceptual states and awareness of sensory stimuli.     

The human Turing machine: a neural framework for mental programs

In recent years much has been learned about how a single computational processing step is implemented in the brain. By contrast, we still have surprisingly little knowledge of the neuronal mechanisms by which multiple such operations are sequentially assembled into mental algorithms. We outline a theory of how individual neural processing steps might be combined into serial programs. We propose a hybrid neuronal device: each step involves massively parallel computation that feeds a slow and serial production system. Production selection is mediated by a system of competing accumulator neurons that extends the role of these neurons beyond the selection of a motor action. Productions change the state of sensory and mnemonic neurons and iteration of such cycles provides a basis for mental programs.     

Age of acquisition: its neural and computational mechanisms

The acquisition of new skills over a life span is a remarkable human ability. This ability, however, is constrained by age of acquisition (AoA); that is, the age at which learning occurs significantly affects the outcome. This is most clearly reflected in domains such as language, music, and athletics. This article provides a perspective on the neural and computational mechanisms underlying AoA in language acquisition. The authors show how AoA modulates both monolingual lexical processing and bilingual language acquisition. They consider the conditions under which syntactic processing and semantic processing may be differentially sensitive to AoA effects in second-language acquisition. The authors conclude that AoA effects are pervasive and that the neural and computational mechanisms underlying learning and sensorimotor integration provide a general account of these effects.     

Dedicated and intrinsic models of time perception

Two general frameworks have been articulated to describe how the passage of time is perceived. One emphasizes that the judgment of the duration of a stimulus depends on the operation of dedicated neural mechanisms specialized for representing the temporal relationships between events. Alternatively, the representation of duration could be ubiquitous, arising from the intrinsic dynamics of nondedicated neural mechanisms. In such models, duration might be encoded directly through the amount of activation of sensory processes or as spatial patterns of activity in a network of neurons. Although intrinsic models are neurally plausible, we highlight several issues that must be addressed before we dispense with models of duration perception that are based on dedicated processes.     

Neural functional organization of hallucinations in schizophrenia: Multisensory dissolution of pathological emergence in consciousness

Although complex hallucinations are extremely vivid, painful symptoms in schizophrenia, little is known about the underlying mechanisms of multisensory integration in such a phenomenon. We investigated the neural basis of these altered states of consciousness in a patient with schizophrenia, by combining state of the art neuroscientific exploratory methods like functional MRI, diffusion tensor imaging, cortical thickness analysis, electrical source reconstruction and trans-cranial magnetic stimulation. The results shed light on the functional architecture of the hallucinatory processes, in which unimodal information from different modalities is strongly functionally connected to higher-order integrative areas.     

Activity Versus Reactivity in Psychology and Neurophysiology

The traditional reflex approach in neurophysiology is incompatible with modern psychology's concern with goal-directed activity. We try to show that a ne~roph~siological approach based on the theory of functional systems may help to solve this problem. According to functional systems theory, all the elements of the organism are organized in systems that are neither sensory nor motor, but functional; the elements of these systems are defined in terms of how they enable the achievement of useful results of behavior. To make our case for this functional systems approach, experimental data are reviewed to illustrate the significance of the behavioral context in determining the activity of both central and peripheral neurons. One key indicator of the functionally specific organization of neural elements is the role of efferent influences in the coordination of the central and peripheral neural processes, and this is discussed at some length here. We offer the present approach as a basis for a new integration of neurophysiology and psy- chology (systemic psychophysiology), an integration which aims not at correla- tions of psychological with neural phenomena, but at their methodologically consistent unification through an understanding of the organization of different levels of the organism-environment system.     

青少年风险决策的发展认知神经机制

随着认知神经科学技术的发展, 青少年风险决策的发展认知神经机制成为了新近的一个热点课题。从双系统理论模型(社会情感神经网络系统、认知控制神经网络系统)出发, 对与青少年风险决策相关的大脑结构、功能的变化进行了阐述, 重点分析了新近的大脑功能连接、脑网络的研究; 阐述了青少年风险决策认知神经机制的主要理论模型：双系统模型和三角模型。未来研究还应加强对认知神经机制理论模型的检验、整合和创新, 从社会认知神经科学的角度深入研究社会参照系统(同伴关系、亚文化等)在青少年风险决策中的作用及机制, 以及从认知神经层面如何预防和干预青少年高风险行为。     

Bridging emotion theory and neurobiology through dynamic systems modeling

Efforts to bridge emotion theory with neurobiology can be facilitated by dynamic systems (DS) modeling. DS principles stipulate higher-order wholes emerging from lower-order constituents through bidirectional causal processes--offering a common language for psychological and neurobiological models. After identifying some limitations of mainstream emotion theory, I apply DS principles to emotion-cognition relations. I then present a psychological model based on this reconceptualization, identifying trigger, self-amplification, and self-stabilization phases of emotion-appraisal states, leading to consolidating traits. The article goes on to describe neural structures and functions involved in appraisal and emotion, as well as DS mechanisms of integration by which they interact. These mechanisms include nested feedback interactions, global effects of neuromodulation, vertical integration, action-monitoring, and synaptic plasticity, and they are modeled in terms of both functional integration and temporal synchronization. I end by elaborating the psychological model of emotion-appraisal states with reference to neural processes.