视觉选择性注意脑机制研究进展

视觉选择性注意一直是认知心理学的研究热点之一。注意的早晚期选择问题和基于空间与基于客体的选择问题是选择性注意研究中长期争论的两大理论问题。脑成像研究不仅为解决这些争论提供了有力的证据 ,而且深化和拓展了这两大问题的研究。该文介绍了脑成像研究在上述两个领域的主要研究成果 ,并展望了今后相关问题的研究重点。     

肢体形状和肢体动作表征的早期发展

肢体是社会性信息的重要载体。研究肢体表征的早期发展对于揭示其肢体表征加工的内在机制, 进一步理解婴儿的社会性发展具有重要意义。从肢体形状和肢体动作两个方面来看, 已有研究主要考察了婴儿在处理肢体结构信息和运动信息时的表征方式, 并提出了婴儿肢体表征发展机制的两种理论。未来应进一步明确婴儿肢体表征的具体发展过程及关键期, 并通过脑成像技术探究生物运动偏好对于肢体表征的作用机制。     

口吃的脑成像研究

口吃(Stuttering)是一种常见的言语流畅性障碍。关于口吃的原因一直有很多争论。近十年来,随着脑成像技术的发展,越来越多的研究者倾向认为口吃是一种中枢神经系统的功能障碍,并尝试用PETf、MRI和MEG等多种方法考察口吃者的脑功能变化。本文围绕几个重要的理论,回顾了近10多年来口吃脑成像研究的进展,提出了各理论相融合的途径,分析了这些研究的价值和问题,讨论了进一步的研究方向。     

探究事件相关脑电/脑磁信号中的神经表征模式：基于分类解码和表征相似性分析的方法

探究不同心智活动下的神经表征差异, 是认知神经科学关注的核心问题之一。早期的脑电/脑磁分析方法主要关注组平均后的神经响应水平, 这要求在关注的时间进程上, 各个被试在相同刺激条件下事件相关电位/事件相关磁场的振幅大小和方向、以及地形图分布和极性均要有较高的一致性。近些年来, 研究者们将功能性磁共振成像研究中常用到的两种技术——机器学习中的分类算法(即基于分类的解码)和表征相似性分析——引入到了脑电/脑磁数据分析中。这两种新技术可以克服传统脑电/脑磁数据基于具体电压/磁感应强度波形平均分析的缺点, 具有在个体水平上探究神经表征编码的特点, 为人们探究大脑在不同时间进程上如何对特定的神经表征信息进行动态编码提供了新的思路。两种技术基于不同的方法学原理来抽提个体间一致的脑认知加工机制, 还为脑电/脑磁研究开展跨时域、跨任务、跨模态、跨群体比较不同认知过程中的表征差异提供了更多新颖的途径。我们首先通过与传统的脑电/脑磁分析方法进行比较, 系统性介绍了基于分类的解码和表征相似性分析的原理和操作流程, 之后对两种方法的应用场景进行了梳理, 并在最后对未来可供研究的方向提出了我们的见解。     

句法加工的脑机制

语言理解中,句法加工至关重要,它把各个意义单元以不同的方式整合起来,从而形成整体的意义表征。句法加工的脑机制是心理语言学比较关注的问题,目前由于ERP技术和功能成像技术的进步,使对这一机制的探讨成为可能。该文对有关句法加工的脑机制的研究进行了回顾与总结,并针对目前该领域存在的问题与争论进行了讨论     

近红外光学成像在社会认知神经科学中的应用

社会认知神经科学是运用认知神经科学的研究手段,探讨社会科学问题与理论的多学科交叉领域。近来,功能性近红外光学成像技术(functional near-infrared spectroscopy,fNIRS)凭借生态效度高、成像安全、对头动耐受性高、成本低等优势,成为了该领域新兴的热点技术。无论是在婴儿发育和社会经济决策的单脑研究中,还是在人际互动的多脑研究中,它都有广泛应用。未来近红外光学成像的应用可以向多脑神经反馈、脑机接口技术、设备无线化和多模态成像做进一步探索。     

情绪加工的脑机制研究及其现状

本文从情绪的效价载荷及其脑功能成像研究、面部表情的识别及其脑功能成像研究以及情绪的诱发及其脑功能成像研究等三方面介绍了情绪加工的脑机制及其研究现状。从现有的研究成果来看,大脑皮层在加工不同效价载荷的情绪时具有很大的重叠性;有关面部表情识别的研究表明,不同的神经环路负责调节对不同面部表情的反应;有关诱发的情绪的研究表明,前扣带回皮层在表征实验诱发的情绪时扮演着一个非常重要的角色。文章最后指出了情绪研究目前面临的一些问题,并指出在我国开展情绪的脑机制研究的重要意义。     

物体位置与空间关系的心理表征

外界环境中物体位置与空间关系在记忆中如何表征,一直是空间认知研究领域探讨和争论的热点问题。该文从空间表征的参照框架、朝向特异性、组织结构和存储内容四个方面,系统回顾了近年来对空间表征形成机制与内在特征的理论探讨。在此基础上,进一步讨论了当前空间表征研究中存在的生态效度问题,以及以后将虚拟环境技术引入到空间认知研究中的发展趋势     

自我概念心理表征的文化神经科学研究

人类自我概念的心理表征在心理学和哲学有深入的研究, 跨文化心理学研究揭示了东西方文化自我概念的结构差异。近年来神经科学借助脑功能成像开始研究自我相关信息加工过程的神经机制, 并探讨是否存在文化特异的自我概念的认知神经表征。跨文化神经成像研究表明自我概念在知觉水平和人格特征表征方面都存在文化差异, 本文综述该领域的研究进展。跨文化和文化启动神经成像研究结果有助于我们理解自我概念表征文化差异背后的神经机制。这些研究推动了文化神经科学的发展。     

Linda问题的表象-命题双表征解释视角探究

本文首先提出了Linda问题的表象-命题双表征这一新的解释视角。该视角认为,Linda问题基于表象表征和命题表征可以有两种不同的解读与表征方式;而不同的被试在Linda问题上可能分别采取了上述表征方式之一;但由于Linda问题的特殊性,大多数被试采用了表象表征;大多数被试的这一表征取向则可能是所谓谬误判断出现的原因。本文通过4项研究,让被试在基于表象表征设计的转述版本与基于命题表征设计的转述版间选择接近自身理解的版本;并考察了将Linda问题修改成更符合命题表征的数学化表达形式能否降低所谓谬误水平;还考察了增加促使被试运用命题表征的排序项"Linda是全人类中的一员"能否降低所谓谬误水平。结果显示,在转述版本选择上,大多数被试选择了基于表象表征设计的版本;而上文所指的两个修正版Linda问题则都降低了被试的所谓谬误水平。这些结果支持了本文所提的视角。     

Mental imagery: in search of a theory

It is generally accepted that there is something special about reasoning by using mental images. The question of how it is special, however, has never been satisfactorily spelled out, despite more than thirty years of research in the post-behaviorist tradition. This article considers some of the general motivation for the assumption that entertaining mental images involves inspecting a picture-like object. It sets out a distinction between phenomena attributable to the nature of mind to what is called the cognitive architecture, and ones that are attributable to tacit knowledge used to simulate what would happen in a visual situation. With this distinction in mind, the paper then considers in detail the widely held assumption that in some important sense images are spatially displayed or are depictive, and that examining images uses the same mechanisms that are deployed in visual perception. I argue that the assumption of the spatial or depictive nature of images is only explanatory if taken literally, as a claim about how images are physically instantiated in the brain, and that the literal view fails for a number of empirical reasons--for example, because of the cognitive penetrability of the phenomena cited in its favor. Similarly, while it is arguably the case that imagery and vision involve some of the same mechanisms, this tells us very little about the nature of mental imagery and does not support claims about the pictorial nature of mental images. Finally, I consider whether recent neuroscience evidence clarifies the debate over the nature of mental images. I claim that when such questions as whether images are depictive or spatial are formulated more clearly, the evidence does not provide support for the picture-theory over a symbol-structure theory of mental imagery. Even if all the empirical claims were true, they do not warrant the conclusion that many people have drawn from them: that mental images are depictive or are displayed in some (possibly cortical) space. Such a conclusion is incompatible with what is known about how images function in thought. We are then left with the provisional counterintuitive conclusion that the available evidence does not support rejection of what I call the "null hypothesis"; namely, that reasoning with mental images involves the same form of representation and the same processes as that of reasoning in general, except that the content or subject matter of thoughts experienced as images includes information about how things would look.     

Intermodal sensory image generation: An fMRI analysis

Although both imagery and perception may be related to more than one sensory input, and information coming from different sensory channels is often integrated in a unique mental representation, most recent neuroimaging literature has focused on visual imaging. Contrasting results have been obtained concerning the sharing of the same mechanisms by visual perception and visual imagery, in part due to assessment techniques and to interindividual variability in brain activation. In recent years, an increasing number of researchers have adopted novel neuroimaging techniques in order to investigate intermodal connections in mental imagery and have reported a high degree of interaction between mental imagery and other cognitive functions. In the present study the specific nature of mental imagery was investigated by means of fMRI on a more extensive set of perceptual experiences (shapes, sounds, touches, odours, flavours, self‐perceived movements, and internal sensations). Results show that the left middle‐inferior temporal area is recruited by mental imagery for all modalities investigated and not only for the visual one, while parietal and prefrontal areas exhibit a more heterogeneous pattern of activation across modalities. The prominent left lateralisation observed for almost all the conditions suggests that verbal cues affect the processes underlying the generation of images.     

Representations in mental imagery and working memory: Evidence from different types of visual masks

Although few studies have systematically investigated the relationship between visual mental imagery and visual working memory, work on the effects of passive visual interference has generally demonstrated a dissociation between the two functions. In four experiments, we investigated a possible commonality between the two functions: We asked whether both rely on depictive representations. Participants judged the visual properties of letters using visual mental images or pictures of unfamiliar letters stored in short-term memory. Participants performed both tasks with two different types of interference: sequences of unstructured visual masks (consisting of randomly changing white and black dots) or sequences of structured visual masks (consisting of fragments of letters). The structured visual noise contained elements of depictive representations (i.e., shape fragments arrayed in space), and hence should interfere with stored depictive representations; the unstructured visual noise did not contain such elements, and thus should not interfere as much with such stored representations. Participants did in fact make more errors in both tasks with sequences of structured visual masks. Various controls converged in demonstrating that in both tasks participants used representations that depicted the shapes of the letters. These findings not only constrain theories of visual mental imagery and visual working memory, but also have direct implications for why some studies have failed to find that dynamic visual noise interferes with visual working memory.     

A motion aftereffect from visual imagery of motion

Mental imagery is thought to share properties with perception. To what extent does the process of imagining a scene share neural circuits and computational mechanisms with actually perceiving the same scene? Here, we investigated whether mental imagery of motion in a particular direction recruits neural circuits tuned to the same direction of perceptual motion. To address this question we made use of a visual illusion, the motion aftereffect. We found that following prolonged imagery of motion in one direction, people are more likely to perceive real motion test probes as moving in the direction opposite to the direction of motion imagery. The transfer of adaptation from imagined to perceived motion provides evidence that motion imagery and motion perception recruit shared direction-selective neural circuitry. Even in the absence of any visual stimuli, people can selectively recruit specific low-level sensory neurons through mental imagery.     

Eye movements disrupt spatial but not visual mental imagery

It has long been known that eye movements are functionally involved in the generation and maintenance of mental images. Indeed, a number of studies demonstrated that voluntary eye movements interfere with mental imagery tasks (e.g., Laeng and Teodorescu in Cogn Sci 26:207–231, 2002). However, mental imagery is conceived as a multifarious cognitive function with at least two components, a spatial component and a visual component. The present study investigated the question of whether eye movements disrupt mental imagery in general or only its spatial component. We present data on healthy young adults, who performed visual and spatial imagery tasks concurrently with a smooth pursuit. In line with previous literature, results revealed that eye movements had a strong disruptive effect on spatial imagery. Moreover, we crucially demonstrated that eye movements had no disruptive effect when participants visualized the depictive aspects of an object. Therefore, we suggest that eye movements serve to a greater extent the spatial than the visual component of mental imagery.     

视觉表象可视化——视觉表象研究的新途径

功能磁共振技术在表象研究中得到广泛应用是表象研究追求客观化精确性的必然趋势。本文介绍了功能磁共振多变量模式分析方法及其演变历程,探讨了借助该方法实现“视觉表象可视化”的理论依据与亟待解决的关键问题。分析指出“视觉表象可视化”将为表象研究提供全新的研究视角与方法途径。     

Mental image generation and the contrast sensitivity function

In one experiment, observers were instructed to generate small and large visual mental images in a light-adapted or a dark-adapted viewing condition, and to rate the vividness of each image. In light-adapted viewing, small images were generated faster than large images. However, the pattern of results was reversed in dark-adapted viewing. Furthermore, the dark-adapted images were more vivid than the light-adapted images. The results show that mental images can be mapped onto some regions of the contrast sensitivity function (CSF), so that the latency (and vividness) of a particular image can be predicted. Since the CSF reflects visual processes occurring mainly in V1, the results agree with functional magnetic resonance imaging data in indicating that early visual pathways participate in imagery. Nonetheless, imagery and perception may involve different processes hosted by the same neural structures as indicated by the direct relationship between image latency and contrast sensitivity.     

Electrophysiological evidence for a shared representational medium for visual images and visual percepts

Does mental imagery involve the activation of representations in the visual system? Systematic effects of imagery on visual signal detection performance have been used to argue that imagery and the perceptual processing of stimuli interact at some common locus of activity (Farah, 1985). However, such a result is neutral with respect to the question of whether the interaction occurs during modality-specific visual processing of the stimulus. If imagery affects stimulus processing at early, modality-specific stages of stimulus representation, this implies that the shared stimulus representations are visual, whereas if imagery affects stimulus processing only at later, amodal stages of stimulus representation, this implies that imagery involves more abstract, postvisual stimulus representations. To distinguish between these two possibilities, we repeated the earlier imagery-perception interaction experiment while recording event-related potentials (ERPs) to stimuli from 16 scalp electrodes. By observing the time course and scalp distribution of the effect of imagery on the ERP to stimuli, we can put constraints on the locus of the shared representations for imagery and perception. An effect of imagery was seen within 200 ms following stimulus presentation, at the latency of the first negative component of the visual ERP, localized at the occipital and posterior temporal regions of the scalp, that is, directly over visual cortex. This finding provides support for the claim that mental images interact with percepts in the visual system proper and hence that mental images are themselves visual representations.