Neurobiology of a Simple Oculomotor System: Circuitry

描述(申请人提供)：这项建议的具体目标是在细胞和突触水平上全面了解唯一识别的无长突细胞和中间神经元之间的功能组织，这些细胞和中间神经元共同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前运动输出神经元，并具有Reichardtian输出。然而，这些小视野神经元之间的排列并不符合Reichardtian模型预测的预期组织，而是显示出Barlow-Levick型检测器的特征，这与某些哺乳动物视网膜中的定向运动检测电路相同。这种基于神经元的双翅目运动检测电路的体系结构与以前的理论“接线图”有很大的不同，因为它在三个连续的阶段重建了定向运动，包括1)无长突细胞水平的非定向运动，2)双极细胞和神经节细胞类似物水平的定向运动和3)定向运动的计算。参与运动计算途径的每一种神经元类型都可以使用特定的抗血清进行唯一识别，从而允许在光学和电子显微镜水平上识别它。标记神经元的细胞内记录和电子显微镜重建，结合计算机建模，将用于测试对功能特性和连接的预测。这些研究将阐明平行通道的功能组织，这些通道为视叶中的子系统提供有关边缘方向、局部图形运动和其他参数的信息，包括刺激速度、加速和减速。基于电生理和突触分析的新模型电路将揭示新出现的需求，这些需求将指导未来的结构和功能研究。这项研究将为双翅目视觉系统的定向运动检测提供基本的见解，并揭示超越系统界限的运动检测的基本原理。它还将导致基于硅的电路的实现，这些电路能够实现运动检测和形状识别，并可能为视觉假肢设备提供基础。

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.