Texture coding in lateral parietal cortex - Resubmission 01

项目总结 纹理是表面材料和微观几何的感官关联。当我们用手指划过一个 表面，我们可以感觉到表面粗糙，像砂纸，或光滑，像玻璃；表面可以 也随着其他感官连续体的变化，例如硬度(例如，石头)与柔软(例如，潮湿的海绵)，或者 粘性(例如，胶带)与滑性(例如，肥皂)。我们对表面纹理的敏感度高达六个数量级 震级：我们可以分辨出从几十纳米到几十毫米的元素。这种能力 依赖于周围神经中的两种不同的神经代码：粗糙的表面元素在空间上编码 一组触觉神经纤维和精细表面元素的激活模式在 另外两组神经纤维中毫秒级精确的时间棘波模式。这两个流 信息反映在顶前皮质(APC)神经元的纹理反应中，其中 神经元沿着一个连续体落下：一端是优先编码粗糙纹理的神经元，并且 对输入的空间模式敏感的另一端是优先编码精细纹理和 对输入的时间模式很敏感。此外，我们对质地的感知与我们如何 触摸表面，但神经和APC中的神经表示取决于 探索性运动。如何实现纹理的宽容表示仍是个未知数。 因此，本研究的目的是探讨侧脑皮层触觉质地知觉的神经基础。 顶叶皮质(LPC)，APC的主要下游目标，使用大量和多样化的人工和 各种与行为相关的探索条件下的自然纹理。我们试图(1)描述 纹理在LPC中的表示以及(2)评估该表示是否容忍探索性中的变化 条件。此外，LPC中的神经元反应已被证明依赖于行为环境 以及这项任务。我们的实验范式将使我们能够探索这种任务依赖。 拟议的实验将阐明高级体感表征，到目前为止已经 几乎没有受到实验上的关注。

PROJECT SUMMARY Texture is the sensory correlate of surface material and microgeometry. When we run our fingers across a surface, we may perceive the surface as being rough, like sandpaper, or smooth, like glass; the surface may also vary along other sensory continua, such as hardness (e.g., stone) vs. softness (e.g. moist sponge), or stickiness (e.g., tape) vs. slipperiness (e.g., soap). Our exquisite sensitivity to surface texture spans six orders of magnitude: We can discern elements measured from tens of nanometers to tens of millimeters. This ability relies on two different neural codes in the peripheral nerve: Coarse surface elements are encoded in a spatial pattern of activation in one population of tactile nerve fibers and fine surface elements are encoded in millisecond precision temporal spiking patterns in two other populations of nerve fibers. These two streams of information are reflected in the texture responses of neurons in anterior parietal cortex (APC), in which neurons fall along a continuum: On one end are neurons that preferentially encode coarse textures and are sensitive to spatial patterns of input, on the other end are neurons that preferentially encode fine textures and are sensitive to temporal patterns of input. Furthermore, our perception of texture is independent of how we touch a surface, but the neural representations in the nerve and in APC are dependent on the nature of exploratory movements. How tolerant representations of texture are achieved remains unknown. The goal of the present study, then, is to investigate the neural basis of tactile texture perception in lateral parietal cortex (LPC), the primary downstream target of APC, using a large and diverse set of artificial and natural textures across the range of behaviorally relevant exploratory conditions. We seek to (1) characterize the representation of texture in LPC and (2) assess whether this representation is tolerant to changes in exploratory conditions. Furthermore, neuronal responses in LPC have been shown to depend on the behavioral context and the task. Our experimental paradigm will allow us to probe this task-dependence. The proposed experiments will shed light on high level somatosensory representations, which to date have received little experimental attention.