Sensorimotor representation of the body multisensory integration and sense of self

自我的概念是心理学的核心，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，但不能移动和控制其他物体。此外，身体感觉事件感觉不同于对外部物体的感知。我们问身体的自我如何与自己的行为和感觉相关联，以及大脑对身体的表征如何改变动作和感觉的处理？要做到这一点，我们需要一种实验方法，让我们能够控制一个事件是否被体验为与我自己的身体有关。我们展示了“橡皮手错觉”(RHI)正是这样做的。受试者看着一只橡胶手被触摸，同时感觉到他们自己看不见的手也有类似的同步触摸。视觉和触觉刺激的知觉规律性导致了橡皮手是自我的一部分的错觉：受试者将橡皮手融入到他们自己身体的精神表征中。这种影响是以自己手的感知位置向橡皮手的方向漂移来客观衡量的。将结果与具有相同视觉和触觉刺激的控制条件进行比较，但它们之间有时间延迟。这种异步性取消了RHI。该项目分为3个阶段。我们首先使用RHI来比较自我感觉的感觉和运动方面。感觉-RHI是由视觉-触觉刺激引起的，如上所述。运动-RHI是通过使用一个看不见的运动，由橡胶手同步或异步重复的简单的手指运动来诱导的。感官--RHI会产生一种“所有权”的感觉：外部物体是身体的一部分。运动-RHI给人一种‘代理’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的感知位置相对于橡皮手的漂移，我们可以评估感觉规律或运动规律对身体自我感觉的贡献更大。自我主要是感觉还是运动？接下来，我们在功能磁共振脑扫描仪中重复这项研究，并调查同步和异步条件下哪些大脑区域不同。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，这可能会整合这些方面。该项目的第二和第三阶段调查自我的感觉和运动方面中的哪一个是最基本的。每一个方面都足够强大，足以影响另一个方面吗？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，然后研究橡皮手的手指运动(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，就像受试者正在模仿他们看到的运动或被他们吸引一样。一项大脑成像研究调查了橡皮手的所有权会影响大脑运动区的大脑过程。在第三阶段，我们研究了运动-RHI和身体感觉体验之间的反向关系。运动-RHI是由随意运动引起的，视频投影手的同步或异步运动。我们测量在有或没有相应刺激的情况下触摸视频手的手的触觉。观看触觉应该增强触觉，尤其是当受试者感觉到被观看的手是他们自己的手时。因此，我们澄清了控制感是否也赋予了归属感，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法来研究大脑的各个方面，这些方面对精神生活至关重要，但以前是科学无法接触到的。该项目将这种关键的自我感觉与特定的大脑过程联系起来，并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.