CORTICAL REPRESENTATION OF THE VISUAL IMAGE

该项目的主要目的是整合来自 空间、时间、方向和双眼域，源自 对无色刺激的反应，转化为基于生理学的描述， V1感受野（r.f.的），并利用这一多方面的评估， 表征V1的不同层和子层内的神经元。 它 提出了一种扩展高斯空间模型差分的方法 关于rf结构包括时间参数。 在最初的实验中，空间，空间频率和方向 V1神经元的调谐将在一个时间调制范围内测量 的刺激。 将得到完整的时空调谐函数 对于每个神经元使用阈值跟踪方法。 此外，回应- 对比度函数将在所选择的点上测量， 时空表面，以获得对比度增益的估计， 压缩对比度非线性的程度。 在第二系列的 实验，单目和双目调谐将被测量和比较， 使用正弦波光栅刺激。 将使用双盲介绍， 确定在不同空间相位、空间 频率和对比度。 在一些实验中，视差灵敏度将 被衡量。 本建议的第三部分是应用详细的 在空间、时间和双目领域采取定量措施， 对细胞进行分类并确定功能类的分布 在不同的皮质层内和穿过不同的皮质层。 其旨在 集中于主要输出层，层2 + 3、4 b、5和6， 其具有明显的纹外或皮层下靶点。 这些 实验将给出一个全面的描述的性质， 神经元提供传入输入到特定的脑外区， 因此，V1对这些区域可用的信息的限制。 的 rf之间的关系尺寸和偏心率将沿着 与锥状光感受器的潜在密度有关。 其目的是获得 地方空间尺度的措施，以及审查是否有任何 局部空间尺度的差异，特别是在中央凹区域， 与圆锥分布有关。 在许多形式的弱视中， 空间和双眼任务，并且认为初级神经元 功能障碍的部位是纹状体皮质。 多维 r.f.的定量描述属性在定义 不同电池类型在不同环境中的预期性能极限 层中的V1的成年猕猴，因此是基本的 发展障碍的认识和治疗 中央视觉通路

The principal aims of this project are to integrate information from the spatial, temporal, directional and binocular domains, derived from responses to achromatic stimuli, into physiologically based descriptions of V1 receptive fields (r.f.'s) and to use this multidimensional assessment to characterize neurons within the different layers and sublayers of V1. It is also proposed to extend the difference of Gaussians based spatial model of r.f. structure to include temporal parameters. In initial experiments the spatial, spatial frequency and orientation tuning of V1 neurons will be measured over a range of temporal modulations of the stimulus. A full spatiotemporal tuning function will be obtained for each neuron using a threshold tracking method. In addition, response- contrast functions will be measured at selected points over the spatiotemporal surface to obtain estimates of the contrast gain and the extent of the compressive contrast non-linearity. In a second series of experiments, monocular and binocular tuning will be measured and compared, using sinewave grating stimuli. Dichoptic presentation will be used to determine binocular interaction at different spatial phases, spatial frequencies and contrasts. In some experiments, disparity sensitivity will be measured. The third part of this proposal is to apply the detailed quantitative measures in the spatial, temporal and binocular domains to categorize cells and determine the distribution of the functional classes both within and across different cortical layers. It is intended to concentrate on the major output layers, layers 2 + 3, 4b, 5 and 6 all of which have distinct extrastriate or sub-cortical targets. These experiments will give a comprehensive description of the properties of the neurons providing afferent input to specific extrastroate areas and therefore the limits of information available to these areas from V1. The relationship between r.f. size and eccentricity will be investigated along with the underlying density of cone photoreceptors. The aim is to obtain measures of local spatial scale as well as to examine whether any differences in local spatial scale, particularly in the foveal region, can be related to the cone distribution. In many forms of amblyopia there is a severe disruption of performance on spatial and binocular tasks, and it is thought that the primary neural locus of the disfunction is the striate cortex. The multidimensional quantitative description of r.f. properties will be important in defining the expected limits of performance of different cell types in different layers in V1 of the adult macaque and is therefore basic to the understanding and treatment of the developmental disorders affecting the central visual pathways.