情绪自动化加工的证据与争议

情绪信息对人类的生存非常重要, 研究者一直在探讨情绪产生的本质问题：情绪的产生是“自动”的吗？已有的大量实验证据表明, 情绪可以被快速识别, 甚至在非注意条件下或者无意识条件下, 情绪信息也可以被大脑(尤其是杏仁核)识别。大量实验结果分析了情绪自动化加工的表现, 并探讨了情绪自动化加工的大脑机制：皮层下通路。视觉信息在视网膜接受后, 经上丘脑与枕核传递至杏仁核, 这条通路被称为皮层下通路, 负责情绪信息的快速化加工。但是新的研究对已有的实验范式与技术手段进行了质疑, 反驳情绪的自动化加工, 并质疑皮层下通路存在的可能性。为了进一步理清情绪加工的本质与大脑机制, 今后的研究应当采用更为严格地控制意识、注意资源的实验范式, 以及采用更精确、更高时间与空间分辨率的技术手段。     

空间频率影响恐惧面孔表情加工的神经通路

恐惧情绪由于其具有威胁性而优先得到有效的加工。其中空间频率作为处理面孔信息的基础成分, 通过不同的神经通路影响恐惧面孔表情的加工。双通路观点认为在皮层下通路上, 低空间频率的恐惧面孔表情存在优先传递性, 高空间频率则主要通过皮层通路对恐惧面孔表情进行精细化加工; 而多通路则能够更加灵活地处理空间频率对情绪加工的影响。未来研究应明确脑区及其子区域在多条通路上的作用, 从而进一步验证视觉信息是如何影响情绪加工的。     

杏仁核对感觉刺激的情绪性加工:自动化过程和注意调控过程的整合

利用有限的认知资源应对多变的环境刺激,选择性注意和情绪加工一个重要的共同机制是优先化关键信息的加工。尽管情绪性刺激(特别是威胁刺激)能够影响注意资源的分配,但一些关键脑区(如杏仁核)的对情绪性刺激的加工是自动化过程还是受到注意调节一直是个有争议的问题。最新的结合高时间分辨率和高空间分辨率的神经生理记录研究表明,情绪加工的重要核团,杏仁核,对情绪性刺激的加工包含早期快速的不依赖于注意资源和认知加工负荷的自动化加工成分和晚期受到额-顶叶皮层自上而下的注意调控成分,这种功能整合证实杏仁核情绪性加工存在并行的皮层下和皮层通路。     

威胁性信息检测的脑机制

快速而准确地检测威胁性信息是进化过程中形成的一种重要能力,是有效应对危险的前提条件,对有机体的生存具有重要价值.威胁性信息的检测由不同的神经通路合作完成.在视觉通道中,皮层通路的精确检测和皮层下通路的快速检测在杏仁核得到整合.杏仁核能接受多感觉通道的信息输入,并接受额叶的调节,是威胁性信息加工中连通自上而下加工和自下而上加工的枢纽.将来的研究需要进一步关注杏仁核的功能以及不同的神经通路如何合作完成威胁性信息的检测.     

猴的记忆系统

基于猴的大量研究证据,本文提出了一个神经模型,假定刺激的编码代表储存于皮层的高级感觉区(即联合区),每当这些区被刺激激活,便触发皮层-边叶-丘脑-皮层环路。这个环路好似铭刻机制或复述机制,实际上可能由两个平行的环路组成,一个包括杏仁和丘脑背内核,另一个包括海马和丘脑前核。经这些环路的作用,储存于皮层的剌激代表被看作是中介三种不同的记忆过程:再认储存的代表被原先的感觉通路再激活而发生;回忆,储存的代表被任何其他通路再激活;联合记忆,通过高级感觉区向相关结构的输出激活其他储存的代表(感觉、情感、空间和运动)。     

触觉的情绪功能及其神经生理机制

触觉是个体探知外部世界的重要感觉通道, 其情绪功能在维系社会联结、促进人际沟通等方面具有重要作用。触觉的情绪功能一方面表现为通过触觉动作本身直接传递情绪信息, 另一方面则是通过增强注意和锐化社会评价的方式促进个体对跨通道情绪信息的加工。神经生理学研究发现, 触觉情绪信息由无髓鞘C纤维介导, 经脊髓丘脑束通路投射于岛叶(头面部触觉情绪信息的传导路径尚不明确), 并在杏仁核、内侧前额叶、后颞上沟等“社会脑”网络的核心区域被精细加工。未来还应对触觉情绪的人际依赖性、文化独特性、操作标准化, 及其在神经水平上与感觉-辨识系统间的关联性与独立性做深入探究。     

颜色运动知觉的研究进展

本文从视觉系统中的P通路与M通路分别独立处理颜色信息与运动信息的传统观点出发,简要介绍了DKL颜色空间和等亮度校正技术在颜色运动知觉研究中的应用、颜色运动知觉的特性以及基于感受器、加工通道和皮层整合等不同加工水平的有关颜色运动知觉的诸多假设。最后,作者尝试性地提出了该领域的研究方向。     

大脑皮层-背侧纹状体通路在吗啡强迫性觅药和用药行为中的作用

药物成瘾是以强迫性觅药和用药行为为核心特征的慢性脑疾病。从初始用药到强迫性用药是成瘾者的觅药行为从目标导向性向习惯化发展的过程。强迫性觅药和用药行为是依赖于背外侧纹状体的习惯化行为, 同时前额叶皮层-背内侧纹状体通路对行为的控制减弱, 导致感觉运动皮层-背外侧纹状体通路对行为的控制持续占主导地位, 是成瘾行为具有强迫性特征的重要神经基础。本项目围绕这一重要问题展开研究, 在建立具有成瘾特征的动物模型的基础上, 采用行为学、行为药理学和组织形态学等方法揭示皮层-纹状体通路在强迫性觅药和用药行为中的作用。研究结果有望为进一步寻找该神经网络参与成瘾行为的分子机制提供重要线索。     

平滑追随眼动的神经机制综述

平滑追随眼动作为视觉引导的眼动行为之一,是指为保障对运动目标的精细觉察,眼睛追随慢速运动的目标以使其处于中央凹位置时眼球的运动情况。本文简要归纳介绍了平滑追随眼动的实验范式、测量指标和影响因素,在此基础上重点详述了平滑追随眼动的皮质-脑桥-小脑神经通路,其中皮质区的额眼区、辅眼区、颞中区、内侧上颞区及侧顶区在平滑追随眼动的产生中具有不同作用;而脑桥核和脑桥被盖网状核作为中继站负责将来自顶枕区和额叶区信号传递到小脑中参与眼动的区域;小脑的绒球和副绒球及蚓体负责处理平滑追随的眼动信号,并协调前庭神经反射。对平滑追随眼动的理解不仅可以帮助我们区分眼动的正常与否,发挥其临床诊断和药理学评估的作用,而且有助于确定患者大脑器质性病变或损伤的程度,同时为进一步的实验认知研究和验证提供理论基础。     

情绪的自动加工与控制加工

由于人类注意资源有限,对相关刺激的加工经常以抑制对其它刺激的加工为代价。大量的研究表明,情绪的加工是注意加工过程的一个特例。通常认为情绪信息的加工是自动的,不需要注意资源的调节。但最近的研究结果倾向于支持对立的观点,即情绪信息的加工需要注意的控制。该文结合认知神经科学研究证据,对情绪的自动加工的观点提出质疑。主要的证据来自对情绪的皮层和皮层下通路的研究以及对盲视病人的研究。     

The brain circuitry of attention

From an operational perspective, attention is a matter of organizing multiple brain centres to act in concert on the task at hand. Taking focal visual attention as an example, recent anatomical findings suggest that the pulvinar might act as a remote hub for coordinating spatial activity within multiple cortical visual maps. The pulvinar can, in turn, be influenced by signals originating in the frontal and parietal eye fields, using common visuomotor neural circuitry, with the superior colliculus acting as an important link. By identifying a complex, real neural architecture ('RNA') model for attention, it is possible to integrate several different modes of operation - such as parallel or serial, bottom-up or top-down, preattentive or attentive - that characterize conflicting cognitive models of attention in visual search paradigms.     

In search of common foundations for cortical computation

It is worthwhile to search for forms of coding, processing, and learning common to various cortical regions and cognitive functions. Local cortical processors may coordinate their activity by maximizing the transmission of information coherently related to the context in which it occurs, thus forming synchronized population codes. This coordination involves contextual field (CF) connections that link processors within and between cortical regions. The effects of CF connections are distinguished from those mediating receptive field (RF) input; it is shown how CFs can guide both learning and processing without becoming confused with the transmission of RF information. Simulations explore the capabilities of networks built from local processors with both RF and CF connections. Physiological evidence for synchronization, CFs, and plasticity of the RF and CF connections is described. Coordination via CFs is related to perceptual grouping, the effects of context on contrast sensitivity, amblyopia, implicit influences of color in achromotopsia, object and word perception, and the discovery of distal environmental variables and their interactions through self-organization. Cortical computation could thus involve the flexible evaluation of relations between input signals by locally specialized but adaptive processors whose activity is dynamically associated and coordinated within and between regions through specialized contextual connections.     

Sources of somatosensory input to the caudal belt areas of auditory cortex

The auditory cortex of nonhuman primates is comprised of a constellation of at least twelve interconnected areas distributed across three major regions on the superior temporal gyrus: core, belt, and parabelt. Individual areas are distinguished on the basis of unique profiles comprising architectonic features, thalamic and cortical connections, and neuron response properties. Recent demonstrations of convergent auditory-somatosensory interactions in the caudomedial (CM) and caudolateral (CL) belt areas prompted us to pursue anatomical studies to identify the source(s) of somatic input to auditory cortex. Corticocortical and thalamocortical connections were revealed by injecting neuroanatomical tracers into CM, CL, and adjoining fields of marmoset (Callithrix jacchus jacchus) and macaque (Macaca mulatta) monkeys. In addition to auditory cortex, the cortical connections of CM and CL included somatosensory (retroinsular, Ri; granular insula, Ig) and multisensory areas (temporal parietal occipital, temporal parietal temporal). Thalamic inputs included the medial geniculate complex and several multisensory nuclei (suprageniculate, posterior, limitans, medial pulvinar), but not the ventroposterior complex. Injections of the core (A1, R) and rostromedial areas of auditory cortex revealed sparse multisensory connections. The results suggest that areas Ri and Ig are the principle sources of somatosensory input to the caudal belt, while multisensory regions of cortex and thalamus may also contribute. The present data add to growing evidence of multisensory convergence in cortical areas previously considered to be 'unimodal', and also indicate that auditory cortical areas differ in this respect.     

Unconscious attentional orienting to exogenous cues: A review of the literature

The present paper reviews research that focuses on the dissociation between bottom-up attention and consciousness. In particular, we focus on studies investigating spatial exogenous orienting in the absence of awareness. We discuss studies that use peripheral masked onset cues and studies that use gaze cueing. The results from these studies show that the classic biphasic pattern of facilitation and inhibition, which is characteristic of conscious exogenous cueing can also be obtained with subliminal spatial cues. It is hypothesized that unconscious attentional orienting is mediated by the subcortical retinotectal pathway. Moreover, a possible neural network including superior colliculus, pulvinar and amygdala is suggested as the underlying mechanism.     

The constructivist brain

How do the representations underlying cognitive skills emerge? It is becoming increasingly apparent that answering this question requires integration of neural, cognitive and computational perspectives. Results from this integrative approach resonate with Piaget's central constructivist themes, thus converging on a 'neural constructivist' approach to development, which itself rests on two major research developments. First, accumulating neural evidence for developmental plasticity makes nativist proposals increasingly untenable. Instead, the evidence suggests that cortical development involves the progressive elaboration of neural circuits in which experience-dependent neural growth mechanisms act alongside intrinsic developmental processes to construct the representations underlying mature skills. Second, new research involving constructivist neural networks is elucidating the dynamic interaction between environmentally derived neural activity and developmental mechanisms. Recent neurodevelopmental studies further accord with Piaget's themes, supporting the view of human cortical development as a protracted period of hierarchical-representation construction. Combining constructive growth algorithms with the hierarchical construction of cortical regions suggests that cortical development involves a cascade of increasingly complex representations. Thus, protracted cortical development, while occurring at the expense of increased vulnerability and parental investment, appears to be a powerful and flexible strategy for constructing the representations underlying cognition.     

The neural bases of difficult speech comprehension and speech production: Two Activation Likelihood Estimation (ALE) meta-analyses

The role of speech production mechanisms in difficult speech comprehension is the subject of on-going debate in speech science. Two Activation Likelihood Estimation (ALE) analyses were conducted on neuroimaging studies investigating difficult speech comprehension or speech production. Meta-analysis 1 included 10 studies contrasting comprehension of less intelligible/distorted speech with more intelligible speech. Meta-analysis 2 (21 studies) identified areas associated with speech production. The results indicate that difficult comprehension involves increased reliance of cortical regions in which comprehension and production overlapped (bilateral anterior Superior Temporal Sulcus (STS) and anterior Supplementary Motor Area (pre-SMA)) and in an area associated with intelligibility processing (left posterior MTG), and second involves increased reliance on cortical areas associated with general executive processes (bilateral anterior insulae). Comprehension of distorted speech may be supported by a hybrid neural mechanism combining increased involvement of areas associated with general executive processing and areas shared between comprehension and production.     

A case of thalamic aphasia with postmortem verification

This study discusses a case of aphasia after dominant thalamic lesion, a hemorrhagic infarction. Unlike other such cases, both repeated standardized assessment and postmortem verification were available. The patient was assessed at 3 weeks and again at 9 weeks postonset. The aphasia demonstrated the syndrome common to dominant thalamic hemorrhage: fluent but paraphasic output sometimes deteriorating to jargon, comprehension less impaired than this type of output usually indicates, and the least impairment in repetition. As sometimes reported in previous cases, semantic paraphasias were more common than phonemic paraphasias. The lesion was located in the dorsal aspect of the lateral nucleus, but it extended into the pulvinar, including the anterior superior lateral aspect which has been implicated in language by previous studies. Thus, data from this case are consistent with an involvement of the dominant pulvinar in language and suggest that this role involves the semantic aspects of language.