Representation of three dimensional shape features in somatosensory cortex

三维形态的感知依赖于手的构象和来自与手的多个接触点的刺激的刺激的整合。为了理解立体感知的神经机制，我们需要了解三件事：1)神经元如何对单个接触点的表面结构做出反应，2)皮肤不同区域的刺激如何整合，以及3)这种整合如何取决于手的构象。这里提出的实验旨在迈出理解3D形式感知的这三个方面的第一步。目的1是确定SI和SII皮层的神经元如何对接触单个手指的3D表面结构做出反应。这项研究将仅限于当手指接触刚性物体时发生的表面曲率和边缘。三维表面结构在与皮肤表面平行和垂直的平面上变化。与目标1相关的实验将研究方向和曲率在与皮肤表面平行的平面上变化的棱角的神经反应以及与皮肤表面垂直的曲面曲率的神经反应。目的2是确定SI和SII皮层的神经元如何对两根手指的刺激作出反应。两个指尖缩进的表面，根据表面的相对运动、方向和曲率，表示物体的不同特征。与目标2相关的实验将研究1)刺激方向和速度的影响；B)边缘方向的影响，c)表面曲率和斜率对相邻手指的影响。目的3是确定面对不同手指位置时客观恒常性的神经机制。当我们用手指扫描一个物体时，来自两个或多个手指的主要信息随着手指的伸展而变化，但感知不受影响。与Aim 3相关的实验集中在聚合机制（本体感觉和皮肤信息之间），当手指外展变化时，必须操作来补偿手指位置。

The perception of 3D form depends on hand conformation and the integration of stimuli of stimuli from the multiple points of contact with the hand. To understand the neural mechanisms underlying stereognosis we need to understand three things: 1) how neurons respond to surface structure at the individual points of contact, 2) how a stimuli at separate regions of skin are integrated, and 3) how this integration depends on hand conformation. The experiments proposed here are aimed at taking a first step towards understanding these three facets of 3D form perception. Aim 1 is to determine how neurons in SI and SII cortex respond to 3D surface structure contacting a single finger. This study will be limited to surface curvature and edges of the kind that occurs when a finger contacts a rigid object. 3D surface structure varies in the plane parallel to and normal to the skin surface. The experiments related to aim 1 will study neural responses to edges and corners whose orientation and curvature vary in the plane parallel to the skin surface and neural responses to surface curvature normal to the skin surface. Aim 2 is to determine how neurons in SI and SII cortex respond to stimuli presented to two fingers. Surfaces indenting tow finger tips signal different things about an object depending on the surfaces' relative motions, orientations, and curvatures. Experiments related to aim 2 will study 1) the effects of stimulus direction and velocity; b) the effects of edge orientation, and c) the effects of surface curvature and slope on adjacent fingers. Aim 3 is to determine the neural mechanisms of objective constancy in the face of varying finger position. When we scan our fingers over an object the primary information from two or more fingers varies with finger spread but the percept is unaffected. The experimented related to Aim 3 concentrate on the convergent mechanisms (between proprioceptive and cutaneous information) that must operate to compensate for finger position when abduction varies.