Investigation of the role and cortico-cortical interactions of the right occipital face area

面孔是丰富的社会信息来源，面孔知觉研究是近年来认知神经科学中最活跃的领域之一。它的重要性相应广泛，人脸处理是社会认知和自闭症、大脑发育、计算机安全过程、记忆、衰老和基本视觉处理研究的关键焦点。这项研究揭示了大脑的三个区域优先对面孔做出反应。这些面孔选择性激活位于梭形回、颞上沟和枕下回。面孔加工的主要模型认为，每个区域在面孔加工中都扮演着特定的角色，其中枕下回的区域，通常被称为枕面区(OFA)，是面孔加工的第一阶段。然而，尽管OFA在这些模型中扮演着关键角色，但它受到的研究关注远远少于其他面孔选择领域。我们已经证明，使用经颅磁刺激(TMS)可以中断右侧OFA的处理，TMS是一种使用磁场干扰小神经区域处理的技术。这为研究人脸知觉提供了一种强有力的新手段。它不仅可以让我们更好地理解正确的OFA，还将提供一种因果方法来检验不同的人脸处理区域是如何相互作用的。我们将解决两个基本问题：1)右OFA的功能是什么，它在什么时候有助于人脸处理？右侧OFA是最接近早期视觉区域的人脸区域，因此人脸处理的模型提出它是人脸处理的初始阶段--通往其他区域的人脸处理的门户。这一观点预测，TMS到正确的OFA将扰乱任何需要人脸处理网络的任务的性能。然而，一些患者的数据与网关视图不一致，而神经成像证据表明，OFA可能专门用于处理来自面部的高空间频率信息。我们将比较在有或没有TMS的情况下的行为任务的表现，以及正确的OFA来评估其功能。作为人脸加工的第一阶段，OFA预计在刺激呈现后不久就会活跃起来。TMS的时间分辨率使我们能够测试这一预测，我们最近的发现为它提供了支持。在两个实验中，右侧OFA的TMS仅在面部出现后60和100毫秒发出脉冲时才中断面部处理。我们将检查此时间窗口是否会中断受TMS影响的其他人脸处理任务，以正确执行OFA。2)正确的OFA与其他脸部选择区域有什么关系？OFA的网关视图建议它向其他面部区域提供输入。然而，尽管这一概念无处不在，但很少有证据表明这一问题。利用功能磁共振成像(FMRI)，我们将确定TMS到右侧OFA是否影响梭形回和颞上沟的面孔选择反应的幅度。我们还将研究右侧OFA TM对杏仁核活动的影响，因为尽管它们不是面部选择性的，但它们对面部处理是重要的。任何这些反应的削弱都将有力地证明，正确的OFA和受影响地区实际上形成了一个网络。与fMRI不同，电生理事件相关电位(ERPs)具有较高的时间分辨率。与其他视觉刺激相比，有几个事件相关电位组件对人脸的反应更强。如果这些面部选择性成分被TMS应用于右侧OFA来调制，将表明右侧OFA为产生这些成分的神经生成器提供输入。

Faces are a rich source of social information, and face perception research has been one of the most active areas in cognitive neuroscience in recent years. Its importance is correspondingly wide ranging and face processing is a key focus in research into social cognition and autism, brain development, computer security processes, memory, aging and basic visual processing. This research has revealed three brain areas that respond preferentially to faces. These face-selective activations are in the fusiform gyrus, the superior temporal sulcus and the inferior occipital gyrus. Leading models of face processing propose that each area plays a particular role in face processing, with the area in the inferior occipital gyrus, commonly known as the occipital face area (OFA), serving as the first stage of face processing. Yet despite the OFA's key role in these models, it has received far less research attention than the other face-selective areas. We have demonstrated that processing in the right OFA can be disrupted using transcranial magnetic stimulation (TMS), a technique that uses a magnetic field to interfere with processing in a small neural region. This provides a powerful new means to investigate face perception. Not only will it allow us to understand the right OFA better, it will also provide a causal method to examine how different face processing areas interact. We will address two fundamental questions: 1) What is the function of the right OFA and when does it contribute to face processing? The right OFA is the closest face area to early visual areas, so models of face processing have proposed that it is the initial stage of face processing--a gateway to face processing in other areas. This view predicts that TMS to right OFA will disrupt performance on any task requiring the face processing network. Some patient data however are inconsistent with the gateway view while neuroimaging evidence indicates that OFA may be specialized for processing high spatial frequency information from faces. We will compare performance on behavioural tasks in the presence or absence of TMS to right OFA to assess its function. As the first stage of face processing, the OFA is expected to be active soon after stimulus presentation. The temporal resolution of TMS allows us to test this prediction, and our recent findings provide support for it. In two experiments, TMS to right OFA only disrupted face processing when pulses were delivered 60 and 100 milliseconds after the face appeared. We will examine whether this time window disrupts other face processing tasks that are affected by TMS to right OFA. 2) What is the relationship between the right OFA and other face-selective areas? The gateway view of the OFA proposes that it provides input to the other face areas. However despite the ubiquity of this notion, very little evidence speaks to this issue. Using functional magnetic brain imaging (fMRI), we will determine whether TMS to right OFA affects the magnitude of the face-selective responses in the fusiform gyrus and the superior temporal sulcus. We will also examine the effects of right OFA TMS on amygdale activity, because although they are not face-selective, they are important for face processing. A weakening of any of these responses would powerfully demonstrate that right OFA and the affected areas do, in fact, form a network. Unlike fMRI, electrophysiological event related potential (ERPs) provide high temporal resolution. Several ERP components show a stronger response to faces than other visual stimuli. If these face-selective components are modulated by application of TMS to right OFA, it will show that the right OFA provides input to the neural generators producing these components.