Role of Parabigeminal Neucleus in Visuomotor Behavior

描述（由申请人提供）：良好的视力需要一个眼球运动系统，它可以对感兴趣的视觉目标进行快速准确的眼球运动，称为扫视。要做到这一点，大脑必须对目标位置有一个内部表征。上丘（SC）是驱动眼睛的脑干回路的扫视命令的主要来源，它通过位置编码编码目标定位和扫视指标：一个视网膜定位图与扫视矢量图在寄存器中。看起来，位于中脑外侧边缘与SC相互连接的一小群细胞——准双侧核（PBN）也对目标位置进行编码，但通过速率编码。当猫在视觉上追踪一个移动的物体时，它们主要依靠一系列的追赶扫视来不断地拦截它。初步研究表明，在追赶性扫视之间的间隔中，PBN细胞的放电速率与眼睛与潜在目标之间的距离或视网膜位置误差（RPE）成正比。在扫视期间，PBN活动突然改变到与扫视结束时的RPE相适应的水平，这种方式似乎太快了，无法进行视觉反馈，这表明活动可能被内部产生的信号重置，例如可重置的眼速积分器或开环前馈信号。PBN与SC在解剖学上的紧密联系表明，PBN主要通过在扫视间隔期间提供目标位置的连续信息来促进扫视系统。它是否对扫视的动态或度量有贡献是未知的。由于SC位置码必须在某个时刻被翻译成驱动眼球运动的速率码，PBN可能为理解如何完成位置码到速率码的转换提供了一个有用的模型。该项目的目标包括更好地定义RPE编码的范围和地形，确定PBN活动是否提供了当前参与扫视目标的索引，检查PBN与SC的相互作用，调查在扫视期间重置PBN活动的信号的性质，以及检查PBN在预测跟踪移动目标中的作用。历史上，在动眼肌生理学和临床神经学之间有一个富有成效的相互作用。PBN似乎是动眼肌系统的重要组成部分，将其纳入动眼肌电路模型将扩展这种有价值的交流。

DESCRIPTION (provided by applicant): Good vision requires an oculomotor system that can make rapid and accurate eye movements, called saccades, to visual targets of interest. To do this, the brain must have an internal representation of target location. The superior colliculus (SC), the main source of saccade commands to brainstem circuits driving the eyes, encodes target localization and saccade metrics by place codes: a retinotopic map of locations in register with a map of saccade vectors. It appears that the parabigeminal nucleus (PBN), a small cluster of cells on the lateral edge of the midbrain that is reciprocally interconnected with the SC, also encodes target location, but by a rate code. When cats visually track a moving object, they rely primarily on a series of catch-up saccades to continually intercept it. Preliminary studies have revealed that in the intervals between catch-up saccades, PBN cells fire at rates proportional to the distance between the eye and potential target, or retinal position error (RPE). During saccades, PBN activity abruptly changes to levels appropriate to RPE at saccade end in a fashion that seems too fast for visual feedback, suggesting that activity may be reset by an internally generated signal, such as a resettable integrator of eye velocity, or an open-loop feedforward signal. Its robust anatomical interconnections with the SC imply that the PBN primarily contributes to the saccade system by providing continuous information on target location during intersaccade intervals. Whether or not it contributes to the dynamics or metrics of the saccade is unknown. Since the SC place code must at some point be translated into a rate code to drive eye movements, the PBN may provide a useful model for understanding how a place-to-rate code translation can be accomplished. The goals of this project include better defining the range and topography of RPE encoding, determining if PBN activity provides an index of the currently attended saccade target, examining PBN interactions with the SC, investigating the nature of the signal that resets PBN activity during saccades, and examining the role of the PBN in predictive tracking of moving targets. Historically, there has been a productive interaction between oculomotor physiology and clinical neurology. The PBN appears to be an important part of the oculomotor system, and its incorporation into models of oculomotor circuits will extend this valuable interchange.