Development of direction selectivity in retina

描述(申请人提供)：方向选择性神经节细胞对图像沿首选方向移动反应强烈，对图像沿相反方向或零方向移动反应弱，并且对于驱动眼运动反射至关重要，当我们在视觉场景中移动时，眼睛运动反射使图像稳定在视网膜上。方向选择性神经节细胞的首选方向沿基本方向(上、下、左、右)聚集，对每个主要方向敏感的方向选择性神经节细胞被组织成马赛克，以便在空间的每个点代表每个运动方向。视网膜产生方向选择性的主要模式是，一类特定的中间神经元在方向选择性神经节细胞树突状细胞的零侧形成抑制性突触。指导嵌合体出现的机制尚不清楚，嵌合体由在发育过程中接受不对称分布的抑制输入的细胞组成。在这里，我们建议使用最先进的电生理和成像技术的组合来确定方向选择性这两个基本特征发展的基础机制-零侧抑制和方向选择性神经节细胞嵌合体的存在的基础电路。特别是，我们将确定自发的视网膜活动是否在这些回路的形成中发挥关键作用。

DESCRIPTION (provided by applicant): Direction-selective ganglion cells respond strongly to an image moving in the preferred direction and weakly to an image moving in the opposite, or null direction, and are critical for driving ocular-motor reflexes that stabilize images on the retina as we move through a visual scene. The preferred direction of direction-selective ganglion cells cluster along the cardinal directions (up, down, left and right) and the direction-selective ganglion cells sensitive to each cardinal direction are organized into mosaics such that at each point in space, each direction of motion is represented. The predominant model for the generation of direction selectivity in the retina is that a particular class of interneurons forms inhibitory synapses on the null side of the dendritic tree of direction- selective ganglion cells. The mechanisms that instruct the emergence of mosaics comprised of cells that receive an asymmetric distribution of inhibitory inputs during development are unknown. Here we propose to use a combination of state-of-the-art electrophysiological and imaging techniques to determine the mechanisms that underlie the development of these two essential features of direction-selectivity - the circuits that underlie the null side inhibition and the existence of direction-selective ganglion cells mosaics. In particular, we will determine whether spontaneous retinal activity plays a critical role in the formation of these circuits.