RETINAL PHARMACOLOGY OF DIRECTIONAL GANGLION CELLS

本研究建议继续提供资助。 EY05978将进一步加深我们对两个功能的理解 视网膜神经元对刺激的检测不足 神经节细胞的方向和这些细胞的功能作用 方向敏感(DS)视网膜输出神经元在视觉上起作用 唤起的行为。DS细胞也存在于许多其他水平的 视觉处理，但尚不清楚不同的DS细胞 使用不同的机制来提取方向信息。 此外，目前还不清楚DS通路是结合还是 争夺他们对行为反应的控制权。建议数 研究通过一种独特的组合来解决这些问题 体外和体内电生理技术以及 记录眼球运动。 我们已经证明，方向性敏感的视网膜神经节细胞可以 使用健康稳定的超融合材料在体外很容易记录 乌龟视网膜眼罩的制备。使用这种技术的实验 准备工作将继续测试突触的效果 递质及其拮抗剂对特异性反应特性的影响 DS视网膜神经节细胞。神经递质的释放 无长突细胞分泌的GABA和ACh对血管紧张素转换酶有显著影响 方向敏感度。同样，外源应用的药物也有 突触过程中对DS细胞放电的直接影响 阻断，表明递质受体存在于 神经节细胞膜。方向性的可能性 敏感性是首先在这个水平上形成的，与最近的 报告说DS反应是从生物极细胞中记录下来的 漂移的栅格。我们将使用常规方法测试这种可能性 在仔细绘制感受野地图后，出现小的斑点刺激。 这里报告的初步研究结果表明，突触药物 在体外对DS视网膜神经节细胞也有效果 在玻璃体内应用时，明显的行为影响。当我们 药物对定向性视网膜病变的影响 敏感度在活体内观察眼动效应 针对视动性眼球震颤(OKN)。OKN是一个合适的 行为需要研究，因为它需要视觉系统的能力 检测刺激方向，以稳定眼球运动 视网膜上的刺激图像。这一知识可能会进一步 OKN在鉴别视网膜和视网膜病变中的诊断价值 中央定向处理。

The research herein proposed as the continuation of grant EY05978 will further our understanding of both the functioning of retinal neurons which underly the detection of the stimulus direction by ganglion cells and the functional role which these directionally sensitive (DS) retinal output neurons play in visually evoked behaviors. DS cells are also found at many other levels of visual processing, but it is not known whether different DS cells use different mechanisms to extract directional information. Furthermore, it is not clear whether DS pathways combine or compete for their control over behavior responses. The proposed research addresses these questions by a unique combination of in vitro and in vivo electrophysiological techniques along with recording eye movements. We've shown that directionally sensitive retinal ganglion cells can be readily recorded in vitro using a healthy and stable superfused retinal eyecup preparation of the turtle. Experiments using this preparation will continue to test the effects of synaptic transmitters and their antagonists on specific response properties of the DS retinal ganglion cells. Release of the neurotransmitters GABA and ACh by amacrine cells have dramatic effects on directional sensitivity. Similarly, exogenously applied agents have direct effects on the spike firing of DS cells during synaptic blockade, suggesting that transmitter receptors are found on the ganglion cell membrane. The possibility that directional sensitivity is first formed at this level is contrary to recent reports that DS responses are recorded from biopolar cells using drifting gratings. We will test this possibility using conventional small spot stimuli after a careful mapping of the receptive field. Preliminary findings reported here show that synaptic drugs that are effective in vitro on DS retinal ganglion cells can also have clear behavioral effects when applied intravitreally. When we pharmacologically perturb the retinal processing of directional sensitivity in vivo we observe eye movement effects which appear specific to optokinetic nystagmus (OKN). OKN is an appropriate behavior to study since it requires the visual system's ability to detect stimulus direction in order for eye movements to stablize the stimulus image on the retina. This knowledge may further OKN's diagnostic usefulness in differentiating retinal versus central directional processing.