Stereoscopic motion-in-depth perception: fMRI and neurophysiological studies

描述（由申请人提供）：该R21探索性提案旨在推进高场fMRI在具有“知情”神经生理学的警觉猕猴中的整合，并将其应用于解决关于立体3-D运动的神经处理的长期研究问题。立体声和运动通常是分开研究的，猕猴的深度运动的双眼知觉所涉及的皮层区域的特点很差，而那些cycloxynia（仅基于视觉）立体运动知觉是未知的。然而，在人类中，最近的研究已经确定了专门参与Cycloprotein立体运动处理的大脑区域，包括一个靠近运动复合体hMT+的区域，称为Cycloprotein立体运动区域。我们已经开发出在高场进行功能磁共振成像研究的技术，在警觉，行为猕猴。因此，采用与人类相同的视觉刺激，我们将使用功能磁共振成像来识别猕猴中的回旋肌立体运动区域，然后表征一个目标区域内的神经元反应。计划中的研究与健康有关，因为立体运动处理中的视野缺陷与聚散眼球运动中的缺陷密切相关，并且双眼相互作用中的相同缺陷似乎是这两种异常行为的基础。对非人类灵长类动物立体运动神经处理的研究不仅将提供对参与处理这种运动信息和控制聚散眼球运动的皮层区域的深入了解，而且还将潜在地有助于斜视和复视的诊断和治疗。具体来说，使用功能磁共振成像，我们将检查激活的皮层区域的回旋，运动的深度刺激与动态随机点立体图（DRDS）。这些刺激将与适当的固定视差DRDS刺激进行对比。我们的初步功能磁共振成像数据从猕猴已经确定了两个很好的本地化灶的激活与这些刺激：一个在上级颞沟（STS）的位置，部分符合MSTv，另一个是在顶内沟。接下来，由于这是一个有限时间的探索性资助，我们将把我们的神经生理学研究集中在STS内的激活的局部焦点上。具体来说，使用MRI引导的电极放置在这个目标区域，我们将寻找反应神经元，而动物查看cycloprotein，运动的深度DRDS刺激与唯一的线索，以运动的深度是随时间的变化差异（CD）。接下来，使用这些刺激，我们将确定感受野的大小和位置，以及神经元的速度调谐和z轴方向选择性。然后，使用RDS刺激，同时具有CD和眼间速度差运动的深度线索，我们将检查神经元的反应时，双目线索的深度。我们将进一步表征立体运动刺激与frontoparallel和倾斜的轨迹，并在聚散眼球运动的神经元反应。公共卫生相关性双眼在不同距离的目标上准确对准需要双眼精确协调的运动，称为聚散眼球运动;聚散眼球运动缺陷的个体通常斜视并报告复视（复视）。立体运动处理中的视野缺陷与聚散眼运动中的缺陷密切相关，并且已经表明双眼相互作用中的相同缺陷是两种异常行为的基础（Regan等人，1986年）。我们对非人类灵长类动物的回旋立体运动的神经处理的研究不仅将提供对参与处理这种运动信息和控制聚散眼球运动的皮质机制的基本见解，而且还将潜在地有助于斜视和复视的诊断和治疗。

Description (provided by applicant): This R21 exploratory proposal is designed to advance the integration of high field fMRI in alert macaque monkeys with "informed" neurophysiology, and to apply it in addressing a long-standing research question regarding the neural processing of stereoscopic 3-D motion. Stereo and motion are usually studied separately, and the cortical regions involved in the binocular perception of motion-in-depth in macaque monkeys are poorly characterized, while those for cyclopean (solely disparity-based) stereomotion perception are unknown. However, in humans, recent studies have identified specialized brain regions specifically involved in cyclopean stereomotion processing, including one near the motion complex hMT+, termed the cyclopean stereomotion region. We have developed techniques for performing fMRI studies at high-field in alert, behaving macaques. Therefore, employing the same visual stimuli as used in humans, we will use fMRI to identify cyclopean stereomotion regions in macaques, and to then characterize neuronal responses within one targeted region. The planned studies are relevant to health, since visual field deficits in stereomotion processing are closely correlated with deficits in vergence eye movements, and the same defect in binocular interaction appears to underlie both abnormal behaviors. Studies of the neural processing of stereomotion in non-human primates will not only provide insights into the cortical areas involved in processing this motion information and in controlling vergence eye movements, but will also potentially aid in the diagnosis and treatment of strabismus and diplopia. Specifically, using fMRI we will examine the cortical areas activated by cyclopean, motion-in-depth stimuli presented with dynamic random-dot stereograms (DRDS). These stimuli will be contrasted with appropriate, fixed-disparity DRDS stimuli. Our preliminary fMRI data from macaques have identified two well-localized foci of activation with these stimuli: one in the superior temporal sulcus (STS) in a location that partially coincides with MSTv, and the other is in the intraparietal sulcus. Next, since this is an exploratory grant of limited duration, we will concentrate our neurophysiological studies on the well-localized focus of activation within the STS. Specifically, using MRI-guided electrode placement in this targeted region, we will search for responsive neurons while the animals view cyclopean, motion-in-depth DRDS stimuli with the only cue to motion-in-depth being the change in disparity over time (CD). Next, using these stimuli, we will determine the receptive field size and location, and the speed tuning and z-axis directional selectivity of the neurons. Then, using RDS stimuli that possess both CD and interocular velocity difference motion-in-depth cues, we will examine neuronal response when both binocular cues to motion-in-depth are present. We will further characterize neuronal responses to stereomotion stimuli with frontoparallel and oblique trajectories, and during vergence eye movements. PUBLIC HEALTH RELEVANCE Accurate binocular alignment of the eyes on targets at different distances requires precisely coordinated movements of the two eyes, known as vergence eye movements; individuals with deficits in vergence eye movements are often strabismic and report diplopia (double-vision). Visual field deficits in stereomotion processing are closely correlated with deficits in vergence eye movements, and it has been suggested that the same defect in binocular interaction underlies both abnormal behaviors (Regan et al., 1986). Our studies of the neural processing of cyclopean stereomotion in non-human primates will not only provide fundamental insights into the cortical mechanisms involved in processing this motion information and in controlling vergence eye movements, but will also potentially aid in the diagnosis and treatment of strabismus and diplopia.