Neurobiology of a Simple Oculomotor System: Circuitry

描述（由申请人提供）：本提案的具体目的是在细胞和突触水平上实现对唯一识别的无长突细胞和中间神经元之间的功能组织的全面理解，这些细胞和中间神经元一起计算视觉运动的方向和方向。自20世纪50年代Hassenstein和Reichardt提出运动知觉的概念回路以来，首次在双翅目视觉系统中发现了一个神经元系统，该系统提供运动敏感的运动前输出神经元，并具有Reichardtian输出。然而，这些小视野神经元之间的排列与Reichardtian模型预测的预期组织不匹配，而是显示出暗示巴洛-莱维克型检测器的特征，与某些哺乳动物视网膜中的定向运动检测电路相同。这种基于神经元的运动检测电路在双翅目的架构显着不同于以前的理论“布线图”，因为它重建定向运动在三个连续的阶段，涉及计算1）无长突细胞水平的无方向运动，和2）定向运动和3）定向运动的水平上的类似物的双极和神经节细胞，分别。参与运动计算通路的每种神经元类型都可以使用特定的抗血清进行唯一识别，从而可以在光镜和电子显微镜水平上进行识别。标记神经元的细胞内记录和电子显微镜重建，结合计算建模，将用于测试有关功能特性和连接的预测。这些调查将阐明平行通道的功能组织，提供子系统的视叶边缘方向，局部图形运动，和其他参数，包括刺激速度，加速度和减速的信息。基于电生理和突触分析的新模型电路将揭示新的需求，这些需求将指导未来的结构和功能研究。这项研究将提供基本的见解方向运动检测的双翅目视觉系统，并揭示运动检测的基本原则，超越种族的界限。它还将导致硅基电路的实现，使运动检测和形状识别，并可能提供视觉假体设备的基础。

DESCRIPTION (provided by applicant): The specific aims of this proposal are to achieve a comprehensive understanding, at the cellular and synaptic level, of the functional organization amongst uniquely identified amacrine cells and interneurons that together compute the orientation and direction of visual motion. For the first time since the formulation in the 1950s by Hassenstein and Reichardt of a notional circuit for motion perception, a system of neurons has been identified in the dipteran visual system that supplies motion-sensitive premotor output neurons and has Reichardtian outputs. Arrangements amongst these small-field neurons do not, however, match the expected organization predicted by the Reichardtian model but instead show features suggestive of a Barlow-Levick type detector, in common with directional motion detection circuits in certain mammalian retinas. The architecture of this neuron-based motion-detecting circuit in Diptera differs significantly from previous theoretical "wiring diagrams" in that it reconstitutes directional motion in three successive stages, involving computation of 1) nondirectional motion at the level of amacrine cells, and 2) oriented motion and 3) directional motion at the level of analogues of bipolar and ganglion cells, respectively. Each neuron type participating in the motion-computing pathway is uniquely identifiable using specific antisera, thus allowing its recognition at the light and electron microscopic levels. Intracellular recordings and electron microscopic reconstructions of marked neurons, in conjunction with computational modeling, will be used to test predictions about functional properties and connections. These investigations will elucidate the functional organization of parallel channels that supply subsystems in the optic lobes with information about edge orientation, local figure motion, and other parameters, including stimulus velocity, acceleration, and deceleration. New model circuits based on electrophysiological and synaptic analyses will reveal emerging requirements that will guide future structural and functional studies. This research will provide basic insights into directional motion detection by the dipteran visual system and reveal principles underlying motion detection that transcend phyletic boundaries. It will also lead to the implementation of silicon-based circuits that enable motion detection and shape discrimination and potentially provide the basis for a visual prosthetic device.