RETINAL PHARMACOLOGY OF DIRECTIONAL GANGLION CELLS

本研究拟作为继续资助项目 EY05978将进一步加深我们对 视网膜神经元是检测刺激的基础 方向的神经节细胞和功能的作用，这些 方向敏感（DS）视网膜输出神经元在视觉上发挥作用 诱发行为 DS细胞也存在于许多其他水平。 视觉处理，但不知道是否不同的DS细胞 使用不同的机制来提取方向信息。 此外，尚不清楚DS途径是否结合联合收割机或 争夺对行为反应的控制权。 拟议 研究通过独特的组合解决了这些问题， 体外和体内电生理技术沿着 记录眼球运动。 我们已经证明，方向敏感的视网膜神经节细胞可以 使用健康和稳定的灌注液在体外容易地记录 海龟的视网膜眼杯制剂。 实验用这个 准备将继续测试突触的影响， 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 GABA和ACh通过无长突细胞对 方向灵敏度 同样，外源性施用的药剂具有 直接作用于突触过程中DS细胞的放电 阻断，这表明递质受体被发现在 神经节细胞膜 定向的可能性 敏感性首先在这个水平上形成， 报告说，DS反应记录从双极细胞使用 漂移光栅 我们将使用常规的 在仔细绘制感受野后的小斑点刺激。 这里报道的初步研究结果表明， 在体外对DS有效的视网膜神经节细胞也可以具有 当玻璃体内应用时有明显的行为效应。 当我们 干扰视网膜的方向性处理 敏感性在体内，我们观察眼动效应， 特异于视动性眼球震颤（OKN）。 OKN是一个合适的 因为它需要视觉系统的能力， 检测刺激方向，以使眼球运动稳定 视网膜上的刺激图像。 这些知识可以进一步 OKN在鉴别视网膜与 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.