视觉意识及其神经机制

视觉意识的神经机制是当前认知神经科学研究的热点问题之一。过去普遍认为视觉信息加工主要有两条通路:腹侧通路和背侧通路;而新近的研究表明还存在不经过初级视觉皮层(V1区)的第三条通路。高级视觉皮层、V1区和皮层下结构都对意识觉知的产生起到了相应的作用。已有的实验证据表明,意识的产生过程异常复杂,仍有很多问题值得继续深入讨论和研究。     

Saccade landing point selection and the competition account of pro- and antisaccade generation: the involvement of visual attention--a review

This paper presents a review and summary of experimental findings on the role of attention in the preparation of saccadic eye movements. The focus is on experiments where performance of prosaccades (saccades towards a suddenly appearing item) and antisaccades (saccades of equal amplitude in the direction opposite to where the target moved) is compared. Evidence suggests that these two opposite responses to the same stimulus event entail competition between neural pathways that generate reflexive movements to the target and neural mechanisms involved in inhibiting the reflex and generating a voluntary gaze shift in the opposite direction to the target appearance. Evidence for such a competition account is discussed in light of a large amount of experimental findings and the overall picture clearly indicates that this competition account has great explanatory power when data on saccadic reaction times and error rates are compared for the two types of saccade. The role of attention is also discussed in particular in light of the finding that the withdrawal of attention by a secondary task 200 to 500 ms before the saccade target appears, leads to speeded antisaccades (without a similar increase in error rates), showing that the results do not simply reflect a speed-accuracy trade-off. This result indicates that the tendency for "reflexive" prosaccades is diminished when attention is engaged in a different task. Furthermore, experiments are discussed that show that as the tendency for a reflexive prosaccade is weakened, antisaccades are speeded up, further supporting the competition account of pro- and antisaccade generation. In the light of evidence from neurophysiology of monkeys and humans, a tentative model of pro- and antisaccade generation is proposed.     

Words, hemispheres, and processing mechanisms: A response to Marsolek and Deason (2007)

Ellis, Ansorge and Lavidor (2007) [Ellis, A.W., Ansorge, L., & Lavidor, M. (2007). Words, hemispheres, and dissociable subsystems: The effects of exposure duration, case alternation, priming and continuity of form on word recognition in the left and right visual fields. Brain and Language, 103, 292–303.] presented three experiments investigating the effects of exposure duration and format (normal vs mixed or alternating case) on the recognition of words presented in the left and right visual fields. The experiments were conducted within the framework of ‘dissociable neural subsystems theory’ developed by Marsolek and colleagues. Marsolek and Deason (2007) [Marsolek, C.J. & Deason, R.G. (2007). Hemispheric asymmetries in visual word-form processing: Progress, conflict, and evaluating theories. Brain and Language, 103, 304–307.] offer some reflections on our paper, including alternative interpretations of some of our findings. We respond to those reflections in this reply.     

后悔的认知机制和神经基础

后悔是基于对不利或相对不利行为结果的反事实思维诱发的一种复杂的负性社会情绪,对我们日常生活的决策和身心健康具有重大的影响。与失望情绪相比,后悔在现象学、产生条件以及评价方式等方面具有明显的差异。后悔不仅会受到个体的行为方式、人格特征、归因等因素的影响,而且还会受到结果信息属性的影响。后悔的预期和体验涉及的功能性脑区主要包括：眶额皮层、扣带前回、海马、杏仁核。研究后悔的实验方法和技术手段有待于进一步拓展,后悔的认知机制和神经基础还有待于进一步探讨和完善     

人眼深度运动知觉的研究

人类的深度运动知觉,是通过检测二维平面内的相对运动而形成的。本文在心理物理学实验基础上,揭示该机制的数学与生理学实现形式。视觉系统中存在对视平面内的相对运动敏感的神经元,构成深度运动的检测机制,产生单眼深度运动知觉与双眼深度运动知觉。在心理学上,视觉利用物体视角变化及大小知觉的恒常性判断深度运动。文中还初步讨论了人类的深度运动知觉与蜜蜂,家蝇等昆虫的深度运动知觉的区别。     

试评外周神经生理效应的函数之争

大量的神经生理学实验久已证实由刺激引起的外周神经生理效应具有类似于心理物理效应的高度压缩现象。从外周神经纤维中观察到的神经脉冲频率或发生电位是描述这种压缩效应的常用方法。半个多世纪以来一部分研究人员观察到压缩效应遵守刺激强度的线性对数函数,而另一部分研究人员则观察到幂函数。这种传统实验分歧,通过笔者前时建立的刺激一效应方程,得到合理的说明和两者的统一     

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.     

信任的认知神经网络模型

信任是指一方在基于对另一方行为期望的基础上愿意冒一定的风险, 以期在将来得到积极结果的心理过程。近年, 认知神经取向的研究对信任行为引起的特定脑区激活进行了考察, 却忽略了大规模脑网络在信任过程中的整体作用。在总结前人研究的基础上提出信任的认知神经网络模型, 并从认知神经网络视角对信任行为进行解释和整合。在模型中, 信任行为是动力系统、情感系统和认知系统相互作用的结果, 并分别与奖励网络、显著网络、中央执行网络和默认网络等神经网络激活有关。此外, 模型还强调信任行为的反馈机制, 以此构成完整的建构模型。模型阐明了心理系统与中枢神经网络之间的对应关系, 从认知神经角度解释了信任行为发生的心理机制和神经基础。     

抑郁症的内表现型:快感缺失及其测量方法

快感缺失,指的是体验快乐的能力下降,广泛出现在抑郁症中,但同时也是其他如精神分裂症的重要症状。虽然快感缺失在精神病理学上非常重要,但较少受到研究重视。文章探讨了抑郁症和快感缺失的关系以及快感缺失个体的大脑奖励系统受损的神经机制,同时介绍了快感缺失可以进一步区分为期待性和消费性两种损害类型以及研究所用的主客观测量方法。指出快感缺失作为抑郁症最有可能的内表现型及其对疾病发展的作用,需要进一步研究深入。