The space of actions - Neural circuits for transforming spatial representations into actions

我听到一个熟悉的声音，我转向它的来源，我看到一辆车驶来，我离开了它，我闻到了一杯咖啡，我伸手去拿。所有这些日常体验最终都与我们与生俱来的空间感有关，我们知道我们周围的东西在哪里，以及如何与它们互动。换句话说，我们能够将多感官体验绑定到一个连贯的感知中，并将其分配到一个有意义的空间框架中，从而适当地指导我们的行动。但是这种多感觉绑定是如何发生的，这样一个连贯的心理空间框架是如何构建的，以及它最终如何被实施来指导动作，这些问题在很大程度上仍然没有解决。近年来，我们已经开始了解动物如何在导航的背景下以位置地图的形式编码空间信息。类似地，空间调整的动作，如到达和定向，可能依赖于个人周围空间的自我中心地图，其神经实现在运动域中变得公开，产生适当的运动矢量。与导航空间相比，对个人周围空间(“触手可及的空间”)进行编码的神经基础以及将其实施为行动的神经机制仍远未被具体化。在这个提案中，我将评估最重要的假设，即这种表征是在运动域中进行的，并依赖于运动执行。我假设大脑通过参与计划和控制三维身体运动的网络的活动来构建认知和感知的空间表征。用法国数学家亨利·庞卡雷(Henry Poincaré)的话说，“将一个物体本地化，意味着向我们展示到达该物体所必须发生的运动”。因此，为了与最近将知觉和认知能力作为主动过程(即主要目标是指导行动的过程)研究的努力保持一致，我提出并旨在测试空间认知的动态、运动路线理论。我会争辩说，实现这一目标最有效的途径是从问题的运动端开始，即从负责产生空间调谐运动的神经元群体开始，逐渐向上游移动，解开负责它们的规划、选择和控制的电路和计算。

I hear a familiar voice and I turn towards its source, I see a car approaching and I move away from it, I smell a cup of coffee and I reach for it. All these daily experiences are ultimately linked to our innate sense of space, we know where things around us are and how to interact with them. In other words, we are able to bind multisensory experiences into a coherent percept and allocate it in a meaningful spatial frame so to appropriately direct our actions. But how this multisensory binding occurs, how such a coherent mental spatial frame is constructed and how it is finally implemented to direct actions remain largely unresolved questions.In recent years, we have begun to understand how animals encode spatial information in the form of allocentric maps, in the context of navigation. Similarly, spatially tuned actions such as reaching and orienting may rely on an egocentric map of peripersonal space, whose neural implementation becomes overt in the motor domain with the production of appropriate movement vectors. In comparison with navigational space, the neural basis of the encoding of peripersonal space ("the space within reach") as well as the neural mechanisms for its implementation into actions remain far less characterised. In this proposal I will assess the overarching hypothesis that this representation is routed in the motor domain and depends on motor execution. I hypothesise that brains construct cognitive and perceptual spatial representations by relying on the activity of networks involved in the planning and the control of three-dimensional bodily movements. In the words of Henry Poincaré, the French mathematician, "localising an object means representing to ourselves the movements that must take place to reach that object". Thus, in line with recent efforts to study perceptual and cognitive abilities as enactive processes (i.e. processes whose primary goal is to guide action), I propose and aim to test a kinetic, motor-routed theory of spatial cognition. I will argue that the most fruitful path to this goal is to start from the motor end of the problem, i.e. from the neuronal populations responsible for the generation of spatially tuned movements, and progressively move upstream to unravel circuits and computations responsible for their planning, selection and control.