Neural correlates of 3D visual orientation

描述(申请人提供)：我们可以看到三维(3D)的东西，因为视觉系统从投射到视网膜上的二维图像重建物体的3D形状。以前的研究已经描述了顶叶病变后的3D双眼视觉丧失和结构性失用，尽管这种影响的神经生理学仍然知之甚少。许多研究已经表征了双眼视差处理的神经基础，尽管很少涉及3D表面方向的表示。这项拟议的研究采用了多方面的方法，有望为顶叶皮质在3D视觉和视觉定向稳定性中的作用提供重要的见解。具体地说，在拟议的研究中，我们通过呈现不同3D取向的平面刺激，同时记录猕猴的尾部顶内区(CIP)、顶前区(AIP)和V3a区的神经元反应，来检验神经元对3D表面取向的选择性。我们采用了一种多方面的方法，结合了神经记录、行为、种群解码和化学失活。这些区域的神经元被调整为在表面方向上倾斜操作，如双目视差或线性透视和纹理梯度所定义的那样。在这里，我们测试了V3a/CIP/AIP神经元的调谐是否代表了倾斜和倾斜的所有组合，以及倾斜和倾斜调谐曲线是否与限定线索、刺激在额叶平行平面上的位置和深度无关。此外，我们还探讨了该区域在视觉方向恒定中的作用，即在世界上头部/身体方向变化时保持场景整体感知稳定定向的能力。我们假设，通过部分调谐曲线移动和增益变化的组合，CIP和AIP中的群体活动实现了视觉定向恒定。这将允许在世界坐标中表示对象的3D方向，这是实现我们与环境的许多交互所必需的属性。此外，我们将使用Fisher信息分析来计算人口阈值如何作为倾斜和倾斜参考方向的函数变化。我们假设，CIP/AIP神经元的特性可以预测行为阈值及其对参考方向的依赖。最后，我们将直接测试这些区域中的每一个在斜视辨别中的因果作用，方法是首先记录并操纵神经活动，同时猕猴执行精细的斜视辨别任务。神经放电率将使用信号检测理论进行分析，神经元敏感度将 与行为敏感性相比。使用相同的数据集，我们还将计算“选择概率”，以确定神经元反应的试验对试验的可变性是否与感知选择的可变性相关。然后，我们将通过使用可逆失活来探索这些区域的神经元与3D表面方位感知之间的因果联系。总而言之，这些研究构成了最先进的多方面方法，并将提供对 这个电路对3D视觉有贡献的假说。

DESCRIPTION (provided by applicant): We can see things in three dimensions (3D) because the visual system reconstructs the 3D configuration of objects from their two-dimensional images projected onto the retina. Previous studies have described loss of 3D binocular vision and constructional apraxia after parietal lesions, although the neurophysiology of this effect remains poorly understood. Many studies have characterized the neural basis of binocular disparity processing, although few have dealt with the representation of 3D surface orientation. The proposed studies use a multi-faceted approach and promise to provide important insights into the role of the parietal cortex in 3D vision and visual orientation constancy. Specifically, i the proposed studies we examine neural selectivity for 3D surface orientation by presenting planar stimuli with different 3D orientations while neuronal responses are recorded from the caudal intraparietal area (CIP), anterior intraparietal area (AIP) and area V3a of macaque monkeys. We employ a multi-faceted approach, combining neural recordings, behavior, population decoding & chemical inactivation. Neurons in these areas are tuned to tilt manipulations in surface orientation, as defined by either binocular disparity or linear perspective and texture gradients. Here we test whether tuning of V3a/CIP/AIP neurons represents all combinations of tilt and slant, as well as whether tilt and slant tuning curves are independent of the defining cue, stimulus position in the frontoparallel plane and in depth. Furthermore, we also explore the role of this area in visual orientation constancy, i.e., the abiliy to maintain the percept of the scene as a whole stably oriented as head/body orientation changes in the world. We hypothesize that, through a combination of partial tuning curve shifts and gain changes, population activity in CIP and AIP achieves visual orientation constancy. This would allow a representation of the 3D orientation of objects in world coordinates, a property that is necessary to implement many of our interactions with the environment. In addition, we will use Fisher information analyses to compute how population thresholds vary as a function of tilt and slant reference orientation. We hypothesize that the properties of CIP/AIP neurons can predict behavioral thresholds and their dependence on reference orientation. Finally, we will directly test for a causal role of each of these areas in slant discrimination by first recording ad then manipulating neural activity while macaques perform a fine slant discrimination task. Neural firing rates will be analyzed using signal detection theory and neuronal sensitivity will be compared to behavioral sensitivity. Using the same dataset, we will also compute 'choice probabilities' to establish whether trial-to-trial variability in neuronal responses is correlated ith variability in perceptual choices. We will then probe for causal links between neurons in these areas and 3D surface orientation perception by employing reversible inactivation. Together, these studies constitute a state-of-the-art multi-faceted approach and will provide a vital test of the hypothesis that this circuit contributes to 3D vision.