Comparison of shape coding in somatosensory and visual cortex

描述（由申请人提供）：本研究计划的目标是研究清醒恒河猴（Macaca mulatta）大脑中2D形式处理的神经机制。具体目标1是表征初级（SI）和次级（Sll）躯体感觉皮层中的神经元对包括弧和角的大量缩进的2D形状的响应。在目标1a中，将使用标准神经生理学技术收集神经反应。使用定制的触觉刺激器将触觉形状呈现给动物的指垫。将使用标准统计分析对缓解进行量化。关于形状处理性质的具体假设（即，代表什么形状信息？）将使用相互竞争的数学模型进行测试。这些模型将测试神经元代表轮廓位置、方向和曲率的程度。目标1b的目标是了解形状信号是如何在单个神经元中导出的。为此，将使用包括时间加权参数的模型来表征形状表示的时间过程。具体目标1的最终目标是理解形状信息如何从SI变换到Sll。目标1 c将联合收割机结合目标1 a和目标1 B的结果，以模拟SI和Sll之间的相互作用。我们的工作假设是，更高级别的神经元（区域2/SII）整合有关简单方向特征的信息（在区域3b/1中处理），以形成角度和曲率的明确表示。具体目标2是测试V4区的视觉神经元是否使用类似的编码策略来表示曲率。在这些实验中，与特定目标1中开发的模型相同类型的模型将应用于先前从V4神经元收集的数据。这些神经元呈现一组类似于特定目标1中使用的触觉形状的2D视觉刺激。形状模型将在视觉神经元的响应上迭代地细化。我们将测试的假设，V4，据报道，代表曲率，处理形状的方式类似于神经元在区域2和Sll的神经元，即通过结合简单的方向特征，形成复杂的轮廓几何的表示。这项研究的最终目的是了解形状信息是如何在大脑中产生和转化的。了解这种转换是理解神经回路如何在感觉运动功能的系统水平上工作的关键。它对未来几代截肢者和盲人神经假肢的设计有重大影响。这些知识也影响了中风、糖尿病和自闭症等发育障碍引起的感觉障碍的临床方法。

DESCRIPTION (provided by applicant): The goal of this research proposal is to investigate neural mechanisms underlying 2D form processing in the brain of the awake rhesus monkey (Macaca mulatta). Specific Aim 1 is to characterize the responses of neurons in primary (SI) and secondary (Sll) somatosensory cortex to a large set of indented 2D shapes comprising arcs and angles. In Aim 1 a, neural responses will be collected using standard neurophysiological techniques. Haptic shapes will be presented to the animal's finger pad using a custom-built tactile stimulator. Responses will be quantified using standard statistical analyses. Specific hypotheses regarding the nature of shape processing (i.e. what shape information is represented?) will be tested using competing mathematical models. The models will test the degree to which neurons represent contour position, orientation, and curvature. The goal of Aim 1b is to understand how the shape signal is derived in individual neurons. To this end, the time course of the shape representation will be characterized using models comprising temporally weighted parameters. A final goal of Specific Aim 1 is to understand how shape information is transformed from SI to Sll. Aim 1 c will combine the results from Aims 1 a and 1 b to model the interactions between SI and Sll. Our working hypothesis is that higher-level neurons (area 2/SII) integrate information about simple orientation features (processed in areas 3b/1) to form explicit representations of angles and curvatures. Specific Aim 2 is to test whether visual neurons in area V4 use similar coding strategies to represent curvature. In these experiments, the same types of models as those developed in Specific Aim 1 will be applied to previously collected data from V4 neurons. These neurons were presented with a set of 2D visual stimuli analogous to the haptic shapes to be used in Specific Aim 1. The shape models will be iteratively refined on the responses of the visual neurons. We will test the hypothesis that neurons in V4, which reportedly represent curvature, process shape in a manner similar to neurons in area 2 and Sll; namely, by combining simple orientation features to form representations of complex contour geometry. The ultimate goal of this proposal is to understand how shape information is generated and transformed in the brain. Knowledge of this transformation is key to understanding how neural circuits work on a systems level in sensorimotor functions. It has major implications on the design of future generations of neural prosthetics for amputees and blind subjects. This knowledge also impacts clinical approaches to sensory deficits caused by stroke, diabetes, and developmental disorders like autism.