Motion processing with two eyes in three dimensions

描述(申请人提供)：物体在三维环境中移动，人类显然能够感知到这种运动的深度。然而，视觉神经学家并不知道我们的神经系统如何编码视觉世界的这一基本方面。尽管有大量关于运动和深度感知的文献，但令人惊讶的是，缺乏将这两个视觉特征整合在一起的知识，来直接表征大脑如何处理运动物体的三维方向。这项拟议的研究的目标是了解灵长类大脑中的神经回路如何利用双目信息来表示物体在3D环境中移动的方向。首先，我们将从心理物理的角度描述3D运动的双眼线索。最近的研究表明，通过深度感知运动依赖于两个双目线索，一个基于随时间变化的视差，另一个基于眼睛间对速度的比较。我们的主要假设是，基于速度的线索对于3D运动的感知非常重要。因此，我们将进行心理物理实验，分离特定于眼睛的运动信号，并将它们与基于视差的信号(以及与其相互作用)进行表征。这些实验将解开这一重要感知信息的心理物理构件和签名，并改进用于神经成像和电生理研究的视觉显示。其次，我们将使用神经成像来识别处理3D运动的神经回路。从我们的心理物理实验中获得刺激和见解，我们将进行fMRI实验，以在人脑中可视化这一过程。方向选择性适配协议将用于表征基于视差和基于速度的线索及其相互作用，并了解这些线索如何(或是否)被集成到3D运动的单一(线索无关)表示中。这些实验还将评估系统的心理物理分析如何直接映射到神经信号上。第三，我们将执行电生理学来指定潜在的神经计算。在心理物理学和神经成像的指导下，我们将进行单神经元记录，以表征编码3D运动的双眼神经信号。V1的录音将使用多电极阵列；MT的录音将使用多四极和单电极唤醒准备。这项工作将检验这样的假设，即眼睛特定的运动信号在V1水平上被表示，然后在MT中被整合(由单个神经元)。该3D运动路径可以以较慢的速度曝光，并且因此可以在使用较快速度进行评估时在已知提取2D/额面平行方向的相同电路中被多路复用。

DESCRIPTION (provided by applicant): Objects move through the environment in three dimensions, and humans are clearly capable of perceiving such motion in depth. Visual neuroscientists do not, however, know how our nervous system encodes this fundamental aspect of the visual world. Despite large literatures motion and depth perception, there is a surprising lack of knowledge integrating these two visual features to directly characterize how the brain processes the three-dimensional direction of moving objects. The goal of this proposed research is to understand how neural circuits in the primate brain exploit binocular information to represent the direction of objects moving through a 3D environment. First, we will psychophysically characterize the binocular cues to 3D motion. Recent work suggests that the perception of motion through depth relies on two binocular cues, one based on changing disparities over time, and one based on an inter-ocular comparison of velocities. Our overarching hypothesis is that the velocity-based cue is of great importance for the perception of 3D motion. We will therefore perform psychophysical experiments that isolate eye-specific motion signals and characterize them relative to (and in interaction with) disparity-based signals. These experiments will unpack the psychophysical building blocks and signatures of this important perceptual information, and refine visual displays used for neuroimaging and electrophysiological studies. Second, we will use neuroimaging to identify the neural circuits that process 3D motion. Taking stimuli and insights from our psychophysical experiments, we will perform fMRI experiments to visualize this processing in the human brain. Direction-selective adaptation protocols will be used to characterize both the disparity-based and velocity-based cues and their interactions, and to understand how (or if) these cues are integrated into a single (cue-independent) representation of 3D motion. These experiments will also assess how directly psychophysical assays of the system map on to neural signals. Third, we will perform electrophysiology to specify the underlying neural computations. Guided by the psychophysics and neuroimaging, we will perform single-neuron recordings to characterize the binocular neural signals that encode 3D motion. Recordings in V1 will employ multi-electrode arrays; recordings in MT will employ both multiple-tetrode and single-electrode awake preparations. This work will test the hypothesis that eye-specific motion signals are represented at the level of V1 and are then integrated (by single neurons) in MT. This 3D motion pathway may be exposed at slower speeds, and thus may be multiplexed in the same circuitry known to extract 2D/frontoparallel direction when assessed using faster speeds.