Face-Specific Activity in the Ventral Stream Visual Cortex Linked to Conscious Face Perception

When presented with visual stimuli of face images,the ventral stream visual cortex of the human brain exhibits face-specific activity that is modulated by the physical properties of the input images.However,it is still unclear whether this activity relates to conscious face perception.We explored this issue by using the human intracranial electroencephalography technique.Our results showed that face-specific activity in the ventral stream visual cortex was significantly higher when the subjects subjectively saw faces than when they did not,even when face stimuli were presented in both conditions.In addition,the face-specific neural activity exhibited a more reliable neural response and increased posterior-anterior direction information transfer in the“seen”condition than the“unseen”condition.Furthermore,the face-specific neural activity was significantly correlated with performance.These findings support the view that face-specific activity in the ventral stream visual cortex is linked to conscious face perception.

Dorsal and ventral streams across sensory modalities

In this review, we describe the current models of dorsal and ventral streams in vision, audition and touch. Available theories take their first steps from the model of Milner and Goodale, which was developed to explain how human actions can be efficiently carried out using visual information. Since then, similar concepts have also been applied to other sensory modalities. We propose that advances in the knowledge of brain functioning can be achieved through models explaining action and perception patterns independently from sensory modalities.

图形形状与空间位置知觉诱发脑电的相干性分析

利用128道高分辨率脑电测量技术及脑电相干处理技术,通过测量大脑对图形形状知觉(任务1)、图形形状和空间位置知觉(任务2)两种任务的事件相关电位,并基于电极数大致相同的原则,从枕叶至额叶把头表分成7个区,然后分析了枕叶与其它各区在不同频段的相干性。结果发现:在"1频段(28～39Hz),任务2时的平均相干系数值显著大于任务1时的相应值;同时还发现在枕叶与额叶间,任务2的相干系数更显著地大于任务1的相干系数。结合视觉的两条通路的理论,这一结果从相干性角度表明,背侧通道的参与强化了枕叶与额叶之间的信息沟通,而这种沟通主要在γ1频段。

视皮层分区及其fMRI研究进展

血氧水平依赖功能磁共振成像(BOLD-fMRI)作为一种无创、可精确定位的脑功能研究技术,已广泛应用于视觉系统的研究中,并取得了许多重要成果,本文就fMRI研究进展及其在大脑视觉皮层功能分区中的应用做一综述。

视觉运动知觉脑机制研究现状

视觉运动知觉问题在整个知觉理论中占有重要的地位,背侧和腹侧的两条视觉通道的发现可以说是近代认知神经科学的一个代表性成就,随着ERP、fMRI等无损探测技术的发展,对人类视觉运动知觉的研究也不断深入,近年来人们利用脑信息学方法,对视觉运动知觉进行了系统的研究,其研究结论将对建立人工智能系统产生深远的影响。

意识与无意识:双流视觉理论

人的心智生活既包括有意识体验也包括各种类型的无意识和非意识的过程。意识研究的方法之一就是在病理学观察中比较特定脑损伤患者身上呈现出的令人瞩目的意识事件与无意识事件的对比。由于敏锐地观察到视觉皮层受损患者DF身上的有意识表现与无意识表现之间令人惊异对比的重要价值,古德尔和米尔纳随后对DF进行了系统而严格的跟踪研究。在《行动中的视觉脑》和《看不见的视觉》这两本著作中,古德尔和米尔纳在传统视觉神经理论基础上提出了一个视觉加工的双流理论,他们认为视觉系统中存在两个视觉信息的加工和利用的通道:一个是知觉视觉,一个是行动视觉,前者通常会造成有意识的视觉体验,而后者能引导行为但通常是无意识的。这个理论为我们在现象学、行为和神经层面理解视觉的意识与无意识的根本差异,以及它们各自的活动特点和如何分工合作提供了一个极为有益的理论参考。

Lessons from human vision for robotic design

The visual guidance of goal-directed movements requires transformations of incoming visual information that are different from those required for visual perception.For us to grasp an object successfully,our brain must use justin-time computations of the object’s real-world size and shape,and its orientation and disposition with respect to our hand.These requirements have led to the emergence of dedicated visuomotor modules in the posterior parietal cortex of the human brain(the dorsal visual stream)that are functionally distinct from networks in the occipito-temporal cortex(the ventral visual stream)that mediate our conscious perception of the world.Although the identification and selection of goal objects and an appropriate course of action depends on the perceptual machinery of the ventral stream and associated cognitive modules,the execution of the subsequent goal-directed action is mediated by dedicated online control systems in the dorsal stream and associated motor areas.The dorsal stream allows an observer to reach out and grasp objects with exquisite ease,but by itself,deals only with objects that are visible at the moment the action is being programmed.The ventral stream,however,allows an observer to escape the present and bring to bear information from the past-including information about the function of objects,their intrinsic properties,and their location with reference to other objects in the world.Ultimately then,both streams contribute to the production of goal-directed actions.The principles underlying this division of labour between the dorsal and ventral streams are relevant to the design and implementation of autonomous robotic systems.

人类视觉引导动作的行为学和脑成像研究

直立行走和工具使用被认为是人类出现的重要标志。直立行走使人类的双手得以解放,因此人类可以使用双手去获取食物,使用工具,大大提升了人类的生存几率。手部动作的完成不仅需要肌肉、骨骼等末端生物器官的参与,更需要大脑对环境中的物体的大小、形状等信息进行分析,选择要完成的动作类型,并对动作进行提前编码和实时调控。本文将从认知神经科学的角度综述视觉引导的手部动作的研究内容、研究方法、已有理论、存在的争议、一些新的证据以及动作研究在机器人和人工智能领域的应用。