Dynamic coding of tactile-to-motor transformation in human and macaque posterior parietal cortex

后顶叶皮层（PPC）是感觉运动转化的中枢结构。然而，它对计划对自己身体的运动的贡献尚不清楚。本项目研究了人类和非人类灵长类动物（猕猴）PPC中目标导向的触觉-运动处理的实现。它的目的是(i)识别相关的顶叶区域，（ii）阐明它们使用的空间代码，以及（iii）描述依赖于执行运动响应的相关效应器将触觉信息从皮肤转换到空间的区域内部和区域之间的动态。三个关键方法是：(a)设计跨两个物种和跨不同方法（功能磁共振成像，行为，神经生理学）的同源，直接可链接的实验；(b)研究两种效应系统（扫视、伸手）的触觉行为，以确定共同和专门的加工机制；(c)在无法进行直接可比范式的情况下，通过针对人类的研究来补充这些共同实验。实验利用了一组共同的关键特征。延迟运动任务涉及亲和反运动将解开被检查任务的感觉和运动方面。实验将直接比较视觉和触觉刺激对跳眼和伸达计划的感觉运动转化，并仔细研究猴子顶叶内外侧、内侧和腹侧视觉运动区域在触摸背景下所起的作用。中枢操作将是通过肢体交叉等姿势操作分离以皮肤为中心、以身体部位为中心和以眼睛为中心的空间编码，在此过程中，例如，身体的右侧部位位于左侧空间。该项目的主要假设是：(1)人类和猕猴的共同原则实际上指导了所有效应系统的运动规划；(2)目前与以眼睛为中心的运动规划相关的后侧区域，如猕猴的LIP/MIP，更普遍地将所有感觉信息编码在以眼睛为中心的代码中；(3)与自我运动和身体表征相关的前侧区域，如猕猴的VIP和SPL；更一般地说，将所有感觉信息编码在以皮肤或身体为中心的代码中，并且(4)所有区域动态地将空间信息从感觉编码到运动目标相关编码。该项目的主要科学贡献是将当前的视觉运动控制概念扩展到触觉领域，作为将身体和自我信息纳入感觉运动控制的第一步。更一般地说，该项目将有助于跨物种的感觉运动加工跨越模式和效应器的综合表征。总的来说，它将因此为理解PPC的功能和区域组织的组织原则提供新的视角。

Posterior parietal cortex (PPC) is a central structure for sensorimotor transformation. Yet, its contribution to planning movements towards the own body is still unclear. This project investigates the implementation of goal-directed tactile-motor processing in human and non-human primate (macaque) PPC. It aims at (i) identifying the involved parietal regions, (ii) elucidating the spatial codes used by them, and (iii) characterizing the dynamics within and between regions involved in transforming tactile information from skin to space in dependence on the involved effector executing the motor response. The three key approaches are (a) to devise homologous, directly linkable experiments across the two species and across different methods (fMRI, behavior, neurophysiology); (b) to investigate tactile behavior across two effector systems (saccades, hand reaching) to identify common and specialized processing mechanisms, and (c) to complement these common experiments by human-specific research where directly comparable paradigms are not feasible.Experiments exploit a common set of critical features. Delayed movement tasks involving pro and anti-movements will disentangle sensory and motor aspects of the inspected tasks. Experiments will directly compare sensorimotor transformation of visual and tactile stimuli for saccade and reach planning, and scrutinize the role monkey lateral, medial, and ventral intraparietal visuo-motor regions play in the context of touch. A central manipulation will be the dissociation of skin-centered, body part-centered, and eye-centered spatial coding through postural manipulations such as limb crossing, during which, say, a right body part is located in left space.The project’s overarching hypotheses are that (1) common principles underlie human and macaque tactually guided motor planning across all effector systems, (2) posterior regions currently associated with eye-centered motor planning, such as macaque LIP/MIP, more generally code all sensory information in an eye-centered code, (3) anterior regions, associated with self-motion and body representation, such as macaque VIP and SPL, more generally code all sensory information in a skin or body-centered code, and (4) all regions dynamically recode spatial information from a sensory to a motor goal-related code.The project’s major scientific contribution is the extension of current visuo-motor control concepts into the tactile domain, as a first step of incorporating information on body and self in sensorimotor control. More generally, the project will contribute an integrated cross-species characterization of sensorimotor processing spanning modalities and effectors. Overall, it will, thus, offer new perspectives for understanding the organizing principles underlying the functional and regional organization of PPC.