Developing an Experimental and Computational Framework for Studying Neural Representations of Tactile Motion on the Hand

项目总结 灵巧地操纵物体依赖于大脑计算，它整合了编码触觉的神经信号 皮肤上的信号与手的本体感觉状态有关。具体地说，编码触觉的神经集合 皮肤上的运动是至关重要的，因为它们向运动规划区域提供反馈信号，以指示是否 一个物体正在从手中滑落。尽管我们很好地理解触觉运动信号是如何 在大脑中，这些知识是从将手放在固定位置的研究中积累起来的。 事实上，所有在单细胞水平上研究触觉运动机制的研究都是在 不执行动作辨别任务的动物，并且将手放在固定的姿势。这些研究 显示触觉运动可以由整合对象不同触觉提示的单元格在区域1中表示 (例如，方向、速度和显著度)。然而，我们最近在人类身上的研究表明，对触觉运动的感知 手指上的运动受手的本体感觉状态和身体部分运动位置的调节 判断是相对于(即，参考系)做出的。这些发现表明，目前的模型 触觉动作需要进行重大修改。也就是说，触觉运动的神经模型应该考虑到 触摸中的运动表示通过本体感觉和/或参考帧信号来变换。因此， 这个应用程序的首要目标是确定神经区域和产生 触觉运动的特定于参考帧的表示。 确定调节特定于参考帧的触觉表征的单细胞机制的关键 动作是记录非人类灵长类动物(NHP)的活动，区分不同触觉运动刺激 参照系，并且他们的手以不同的姿势放置。不幸的是，我们的领域没有 建立了研究NHP中这些运动机制的范例或培训制度。在AIM I中，我们开发了一种 训练NHP辨别手指(例如食指)上刺激的运动方向的行为范式 在不同的参考系(例如，相对于身体中心或拇指)中，当他们的手被放置时 不同的本体感觉状态(例如，内翻与后仰)。在AIM II中，我们将记录#年的单位活动 受过训练的NHP的躯体感觉皮层(区域1)，以确定产生参考的神经计算 触觉运动的帧特定表示。我们的行为实验将测试这种知觉 在NHP和人类之间，触觉运动的表示是保守的，表明NHP是一种可行的 在单细胞水平上研究触觉运动的神经机制。我们的神经生理学实验 将测试第一区的运动选择性神经元，这是视觉的内侧颞叶皮质的触觉类似物 运动，灵活地表示不同参考系中的运动。这个项目将第一次展示， NHP执行触觉运动辨别任务的行为和神经生理学证据，一个关键的 竞争对手R01类型应用程序的必备条件。

PROJECT SUMMARY Dexterous manipulation of objects relies on brain computations that integrate neural signals encoding tactile signals on the skin with the proprioceptive state of the hand. In particular, neural ensembles that encode tactile motion on the skin are critical because they provide feedback signals to motor planning areas to indicate whether an object is slipping from the hand. Although we have a good understanding of how tactile motion signals are represented in the brain, this knowledge has been accrued from studies that placed the hand in a fixed position. Indeed, all studies that have investigated tactile motion mechanisms at the single-cell level have done so in animals not performing a motion discrimination task, and with their hands placed in a fixed posture. These studies show that tactile motion can be represented in area 1 by cells that integrate different tactile cues of the object (e.g., direction, speed, and saliency). However, our recent work in humans shows that perception of tactile motion on a finger is modulated by the proprioceptive state of the hand, and the body part location in which motion judgements are made relative to (i.e., the reference frame). These findings indicate that current models of tactile motion require major revisions. That is, neural models of tactile motion should take into account how motion representations in touch are transformed by proprioception and/or reference frame signals. Thus, the overarching goal of this application is to determine the neural areas and mechanisms that generate reference frame-specific representations of tactile motion. Key to determining the single-cell mechanisms that mediate reference frame-specific representations of tactile motion is to record activity in non-human primates (NHPs) discriminating tactile motion stimuli in different reference frames, and with their hands placed in different postures. Unfortunately, our field does not have an established paradigm, or training regime, to study these motion mechanisms in a NHP. In Aim I, we develop a behavioral paradigm to train NHPs to discriminate the motion direction of stimulus on a finger (e.g., index finger) in different reference frames (e.g., relative to the center of the body, or the thumb), while their hands are placed different proprioceptive states (e.g., pronated vs. supinated). In Aim II, we will record single-unit activity in somatosensory cortex (area 1) in trained NHPs to determine the neural computations that generate reference frame-specific representations of tactile motion. Our behavioral experiments will test that perceptual representations of tactile motion are conserved across NHPs and humans, demonstrating that NHPs are a viable species to study neural mechanisms of tactile motion at the single cell level. Our neurophysiology experiments will test whether motion selective neurons in area 1, the tactile analogue of medial temporal (MT) cortex for visual motion, flexibly represent motion in different reference frames. This project will demonstrate, for the first time, behavioral and neurophysiological evidence of NHPs performing tactile motion discrimination tasks, a crucial prerequisite for a competitive R01-type application.