Representation of three dimensional shape features in somatosensory cortex

3D形式的感知取决于手的构造和来自与手接触的多个点的刺激的刺激的整合。为了理解立体觉背后的神经机制，我们需要了解三件事：1）神经元如何对各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）这种整合如何依赖于手的构造。这里提出的实验旨在采取第一步理解这三个方面的3D形式感知。目的1是确定SI和SII皮层中的神经元如何对接触单个手指的3D表面结构作出反应。这项研究将仅限于表面曲率和边缘的那种发生时，手指接触刚性物体。3D表面结构在平行于和垂直于皮肤表面的平面中变化。 与目标1相关的实验将研究对边缘和拐角的神经响应，边缘和拐角的方向和曲率在平行于皮肤表面的平面内变化，以及对垂直于皮肤表面的表面曲率的神经响应。目的2是确定SI和SII皮层神经元对两个手指刺激的反应。表面缩进两个指尖信号不同的事情有关的对象取决于表面的相对运动，方向和曲率。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;以及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定性的神经机制。当我们用手指扫过一个物体时，来自两个或多个手指的主要信息会随着手指的伸展而变化，但感知不受影响。与目标3相关的实验集中在会聚机制（本体感受和皮肤信息之间）上，该会聚机制必须在外展变化时操作以补偿手指位置。

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.