Mechanisms of Synaptic Processing in the Retina

视网膜突触处理机制

• 批准号: 6914439
• 负责人: William Rowland Taylor
• 金额: $ 33.98万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6914439
• 关键词: biological signal transduction; dendrites; evoked potentials; interneurons; laboratory rabbit; neural conduction; neural information processing; neural inhibition; neural initiation; neurophysiology; neurotransmitter metabolism; retina; synapses; voltage /patch clamp

DESCRIPTION (provided by applicant): How the brain resolves the direction of external motion from the pattern of light passing across the retina has puzzled neuroscientists for decades. Neurons that encode the direction of image motion are first encountered in the retina. The neurons are the on-off direction-selective ganglion cells (DSGCs). We will examine in isolation the convergent synaptic mechanisms that generate direction selectivity, and determine how they arise, and how they are integrated by the DSGC. Comparison of the results obtained from this system, with those in other brain regions and other species, will provide new insights into how neural circuits remove redundant information, and extract specific features or patterns from the barrage of incoming synaptic activity. Each DSGC determines the direction of image motion in a small region of visual space. These cells are most selective for movement along a preferred-null axis. Their responses are largest for movement in the preferred direction and smallest for movement in the opposite, null direction. Our preliminary recordings indicate that a mix of synaptic mechanisms generate direction-selective responses. The excitatory and inhibitory inputs to DSGCs are directional, indicating that there is presynaptic modulation of neurotransmitter release from interneurons. Directional responses are also generated within the dendrites of the DSGC, and arise from the postsynaptic integration of excitatory and inhibitory synaptic inputs. A striking finding is that the two distinct dendritic arbors of DSGCs use different synaptic mechanisms to generate a directional signal. The proposed research will use whole-cell patch-clamp recording techniques to analyse the visually evoked synaptic responses in DSGCs in an in vitro rabbit retina preparation. The first aim will determine the origin and nature of the lateral inhibition that is critical for generating direction-selective responses. The second aim will be to determine the synaptic mechanisms that generate directional excitatory inputs to the DSGCs. The third aim will further test the hypothesis that the two dendritic strata generate directional signals using different synaptic mechanisms.

描述（由申请人提供）：大脑如何从穿越视网膜的光模式中解决外部运动的方向，使神经科学家感到困惑数十年。编码图像运动方向的神经元首先在视网膜中遇到。神经元是开关式选择性神经节细胞（DSGC）。我们将分别检查产生方向选择性的收敛突触机制，并确定它们的产生方式以及如何通过DSGC整合它们。比较从该系统获得的结果与其他大脑区域和其他物种的结果，将提供有关神经回路如何消除冗余信息的新见解，并从传入的突触活动中提取特定特征或模式。 每个DSGC确定在视觉空间的一小区域中图像运动的方向。这些细胞最有选择性地沿着首选的无轴轴运动。他们的响应最大的是沿首选方向运动，并且在相反的无效方向上运动最小。我们的初步记录表明，突触机制的混合会产生方向选择反应。 DSGC的兴奋性和抑制性输入是定向的，表明神经递质从中间神经元释放了突触前调节。定向反应也是在DSGC的树突中产生的，是由兴奋性和抑制性突触输入的突触后整合产生的。一个惊人的发现是，DSGC的两个不同的树突状乔木使用不同的突触机制来产生定向信号。 拟议的研究将使用全细胞斑块钳记录技术来分析体外兔视网膜制备中DSGC中的视觉引起的突触反应。第一个目标将确定横向抑制的起源和性质，这对于产生方向选择反应至关重要。第二个目的是确定对DSGC产生定向兴奋性输入的突触机制。第三个目标将进一步检验以下假设：两个树突状地层使用不同的突触机制产生方向信号。