Texture coding in lateral parietal cortex - Resubmission 01

项目摘要 质地是表面材料和微观几何形状的感官相关物。当我们的手指划过一个 表面，我们可能会认为表面粗糙，像砂纸，或光滑，像玻璃;表面可能 也沿着其它感觉连续体变化，例如硬度（例如，石头）与柔软度（例如湿海绵），或 粘性（例如，胶带）与滑度（例如，肥皂）。我们对表面纹理的灵敏度可达六个数量级， 我们可以分辨从几十纳米到几十毫米的元素。这种能力 依赖于外周神经中的两种不同的神经代码：粗糙的表面元素被编码在空间编码中， 触觉神经纤维和精细表面元素的一个群体中的激活模式被编码在 毫秒精度的时间尖峰模式在其他两个群体的神经纤维。这两股 信息反映在前顶叶皮层（APC）神经元的纹理反应中，其中 神经元沿着一个连续体：一端是优先编码粗糙纹理的神经元， 对输入的空间模式敏感，另一端是优先编码精细纹理的神经元， 对输入的时间模式很敏感。此外，我们对纹理的感知与我们如何 触摸表面，但神经和APC中的神经表征取决于 探索性的运动。如何实现纹理的宽容表示仍然是未知的。 因此，本研究的目标是探讨侧位触觉纹理感知的神经基础。 顶叶皮质（LPC），APC的主要下游靶点，使用大量不同的人工和 在行为相关的探索条件范围内的自然纹理。我们试图（1）描述 在LPC中的纹理表示和（2）评估这种表示是否是宽容的变化，探索 条件此外，LPC中的神经元反应已被证明取决于行为背景 和任务我们的实验范式将使我们能够探索这种任务依赖性。 拟议的实验将阐明高层次的体感表征，迄今为止， 很少受到实验的关注。

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.