The Computation of Direction Selectivity in the Retina

运动的视觉检测是通过选择性地对视野中的运动方向做出反应的神经元进行的。当移动的物体以适当的方向穿过它们的感受野时，视网膜神经节中的细胞会发出开/关的反应。这意味着存在抑制这些细胞反应的神经回路，而这些回路正是本项目的研究对象。这项研究解决了四个主要问题：1.这些细胞对方向选择性是必不可少的，还是它们只是决定速度和方向的功能？2.视网膜中的抑制和兴奋是如何相互作用的？3.抑制与细胞对速度和方向选择性的调谐有何关系？4.抑制对被感知物体的对比度有多大的依赖性？所采用的方法包括电生理学、药理学和免疫组织化学，并对数据进行计算理论分析。这项工作意义重大，原因有很多。它包括对一般机制的分析，这些机制可能是大脑功能的基础。它还将展示早期运动测量的局限性，可能会对运动感知的预期设定限制。最后，它包括开发新的实验和理论工具，这些工具将适用于研究大脑高级中枢的运动感知机制。*//

Visual detection of motion occurs via neurons that selectively respond to the direction of movement in the visual field. Cells in the retinal ganglia give ON/OFF responses when moving objects cross their receptive fields in appropriate directions. This implies that there are neural circuits that inhibit the responses of these cells, and it is those circuits that are the object of investigation in this project. The study addresses four major questions: 1. Are these cells essential to direction selectivity or do they simply function in determining velocity and orientation? 2. How does the inhibition interact with excitation in the retina? 3. How does the inhibition relate to the cells' tuning to velocity and direction selectivity? 4. How dependent is the inhibition on the contrast of the object whose motion is being perceived? The methods employed include electrophysiology, pharmacology and immunohistochemistry, with computational theoretical analysis of the data. The work is significant for a number of reasons. It includes analysis of general mechanisms that are probably fundamental to the function of the brain. It will also demonstrate the limitations of early motion measurements, perhaps setting constraints on what may be expected of motion perception. Finally, it includes the development of new experimental as well as theoretical tools that will be applicable to studies of motion perception mechanisms in higher centers of the brain. *** //