Sensorimotor representation of the body multisensory integration and sense of self

自我的概念，被称为“我”，是心理学的核心，但很难进行科学研究。自我的基础必须是身体。身体在大脑中的表现与外部物体不同。首先，我可以直接移动和控制我的身体，但不能控制其他物体。此外，身体感觉事件的感觉不同于对外部物体的感知。我们会问，身体的自我是如何与自己的行为和感觉联系起来的，大脑对身体的表征是如何改变行为和感觉处理的？要做到这一点，我们需要一种实验方法，使我们能够控制一个事件是否与我自己的身体有关。我们发现“橡胶手错觉”（RHI）正是这样做的。实验对象一边看着一只橡胶手被触摸，一边感觉自己看不见的手也被触摸。视觉和触觉刺激的知觉规律性引起了一种错觉，即橡胶手是自己的一部分：受试者将橡胶手纳入自己身体的心理表征中。这种影响是客观地衡量的，即一个人的手在感知到的位置上向橡胶手的漂移。将结果与具有相同视觉和触觉刺激的控制条件进行比较，但两者之间存在时间延迟。这种异步消除了RHI。该项目分为三个阶段。我们首先用RHI比较自我意识的感觉和运动方面。感官- rhi是由视觉-触觉刺激引起的。motor - rhi是由橡胶手使用一个看不见的马达，通过重复做一个简单的手指动作来引起的，这个动作可以同步或不同步地重复。感觉- rhi诱导“所有权”的感觉：外部物体是自己身体的一部分。Motor-RHI给人一种“能动性”的感觉：一个人可以通过自己的命令直接控制橡胶手。通过比较一个人的手对橡胶手的感知位置的漂移，我们可以评估感官或运动规律对身体自我感的贡献更大。自我主要是感觉的还是运动的？接下来，我们在fMRI脑部扫描仪上重复这项研究，并研究同步和异步条件下大脑的哪些区域不同。这揭示了负责自我感觉和运动方面的大脑区域。我们还寻找共同重叠的领域，这些领域可能整合这些方面。项目的第二和第三阶段调查自我的感觉和运动方面哪个是最基本的。每个方面是否都有足够的力量去影响其他方面？在第二阶段，我们评估感觉自我是否会影响运动系统。我们诱导感觉rhi，然后研究橡胶手的手指运动（通过看不见的马达）是否会自动激活受试者大脑中的运动区域，就好像受试者正在模仿或被他们所看到的运动所吸引一样。一项脑成像研究调查了拥有橡胶手可以影响大脑运动区域的大脑过程。在第三阶段，我们研究运动- rhi与身体感官体验之间的反比关系。Motor-RHI是由视频投射的手的同步或异步的自主运动引起的。我们测量手的触觉，无论有没有相应的刺激触摸视频手的视觉。观看触摸应该增强触觉感知，当受试者感觉到被观看的手是他们自己的手时，这种感觉最强烈。因此，我们澄清了控制感是否也赋予了所有权感，并使用功能磁共振成像来研究大脑中这种联系的基础。因此，该项目提供了一种实验和科学的方式来研究精神的各个方面，这些方面对精神生活至关重要，但以前是科学无法达到的。该项目将这种关键的自我意识与特定的大脑过程联系起来，并将其与清晰描述的感觉和行动体验联系起来。

The concept of self, something referred to by 'I', is central to psychology, but hard to study scientifically. The basis of self must be the body. The body is represented in the brain differently from external objects. First, I can directly move and control my body, but not other objects. Also, bodily sensory events feel different from perceptions of external objects. We ask how the bodily self relates to one's own actions and sensations, and how the brain's representation of the body modifies action and sensation processing? To do this, we need an experimental method that allows us to control whether an event is experienced as linked to my own body or not. We showed that 'Rubber Hand Illusions' (RHI) do precisely this. Subjects watch a rubber hand being touched while feeling a similar, synchronous touch on their own unseen hand. Perceptual regularity of the visual and tactile stimuli induces the illusion that the rubber hand is part of one's self: subjects incorporate the rubber hand into the mental representation of their own body. The effect is measured objectively as a drift in the perceived position of one's own hand towards the rubber hand. Results are compared to control conditions with identical visual and tactile stimuli are, but separated by a time delay between them. This asynchrony abolishes RHI. The project has 3 phases. We first compare sensory and motor aspects of sense of self using RHI. Sensory-RHI is induced by visual-tactile stimulation as above. Motor-RHI is induced by repeatedly making a simple finger movement which is repeated synchronously or asynchronously by the rubber hand, using an invisible motor. Sensory-RHI induces the feeling of 'ownership': that an external object is part of one's body. Motor-RHI induces a feeling of 'agency': that one can control the rubber hand directly by one's own command. By comparing the drift in the perceived position of one's hand towards the rubber hand, we can assess whether sensory or motor regularity makes a stronger contribution to the sense of bodily self. Is the self primarily sensory or motor? We next repeat the study in an fMRI brain scanner, and investigate which brain areas differ between synchronous and asynchronous conditions. This reveals brain regions responsible for sensory and motor aspects of self. We also look for areas of common overlap, which may integrate these aspects. The second and third phases of the project investigate which of the sensory and motor aspects of self is most fundamental. Is each aspect sufficiently powerful to influence the other? In phase 2, we assess whether the sensory self can influence motor systems. We induce sensory-RHI and then study whether a finger movement of the rubber hand (via the invisible motor) automatically activates the motor areas in the subject's brain, as if subjects were imitating or entrained by the movement that they see. A brain imaging study investigates the brain processes whereby ownership of the rubber hand can influence motor areas of the brain. In phase 3, we study the inverse relation, between motor-RHI and the sensory experience of the body. Motor-RHI is induced by voluntary movements, with synchronous or asynchronous movements of a video-projected hand. We measure the sense of touch in the hand with or without vision of a corresponding stimulus touching the video hand. Viewing touch should enhance tactile perception, and most strongly when the subject feels that the viewed hand is their own. We thus clarify whether sense of control also imparts a sense of ownership, and use fMRI to study the basis of this link in the brain. The project therefore provides an experimental and scientific way of studying aspects of the mind which are crucial to mental life, but have previously been inaccessible to science. The project links this key sense of self to specific brain processes, and to clearly-described experiences of sensation and action.