STRUCTURE AND FUNCTION OF PARALLEL CHANNELS IN THE FOVEA

中央凹平行通道的结构和功能

• 批准号: 6778688
• 负责人: PETER STERLING
• 金额: $ 45.43万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6778688
• 关键词: cell type; electron microscopy; electrophysiology; ferritin; fovea centralis retinae; guinea pigs; hypoxia; immunocytochemistry; membrane channels; neural information processing; neuroanatomy; neuronal transport; retinal adaptation; retinal ganglion; synapses; synaptic vesicles; visual pathways; visual stimulus; voltage gated channel

DESCRIPTION (provided by applicant): Our broad goal is to investigate key 'design' principles by which the primate retina transfers large amounts of information to the brain. Its 106 axons are strikingly heterogeneous. They comprise 15 channels, spanning a 50-fold range in axon diameter and a 10-fold range in spike rate. Noting that foveal circuits are strongly constrained for space and energy, we hypothesize that multiple channels exist in order to relay information at least cost in "wire volume' and metabolic energy. Preliminary studies suggest that channels transmitting at low information rates (few bits/second) are more efficient (more bits/spike) and physically smaller, thus using less space and probably less energy per bit. Thus central nuclei, which acquire information at different rates (e.g. geniculate M vs. K layers), can receive their messages at least cost. To test this, AIM 1 will measure for several ganglion cell types: (a) 'natural information rate' (bits/spike and bits/s in response to natural images); (b) total wire volume (soma + dendrites + axon + terminal arbor)(cell density); (c) relative energy costs, i.e., mitochondrial content. We predict that natural information rates differ strongly across channels and that 'low-rate' channels use less space and energy per bit. Noting that OFF channels are spatially finer and denser than ON channels and that 'blue/yellow' channels also occur on two spatial scales, we hypothesize that receptive field sizes and sampling rates are tuned to the distribution of information in natural scenes. To test this, AIM 2 will measure achromatic and chromatic information in natural images on scales corresponding to known receptive fields. We predict that in nature dark regions occupy higher spatial frequencies and contain more information per retinal area than bright regions and thus require finer channels with more synapses; there are analogous predictions for the blue/yellow channels. Noting that information transfer through the retina relies on 'ribbon' synapses, we hypothesize that they release and retrieve vesicles at very high rates. To test this, AIM 3 will measure release rates at the cone synapse (2-photon + electron microscopy of FM1-43 dye), and AIM 4 will measure the rates at the bipolar synapse (electrophysiology + EM of ferritin). Glaucoma, a major cause of blindness, has been attributed to both ganglion cell anoxia and reduced axonal transport. Our studies will relate ganglion cell signaling to both oxidative capacity and axonal transport capacity, and thus should extend the basic foundation for future clinical studies.

描述（由申请人提供）：我们的主要目标是研究灵长类动物视网膜将大量信息传递到大脑的关键“设计”原则。它的106个轴突是惊人的异质性。它们包括15个通道，跨越轴突直径的50倍范围和尖峰速率的10倍范围。注意到中央凹电路的空间和能量受到很大的限制，我们假设存在多个通道，以中继信息至少在“线体积”和代谢能量的成本。初步研究表明，以低信息速率（几比特/秒）传输的信道更有效（更多比特/尖峰），物理上更小，因此使用更少的空间和可能更少的每比特能量。因此，以不同速率获取信息的中央核团（例如膝状体M层与K层）可以以最低的成本接收它们的信息。为了测试这一点，AIM 1将测量几种神经节细胞类型：（a）“自然信息率”（响应于自然图像的位/尖峰和位/秒）;（B）总丝体积（索马+树突+轴突+末端乔木）（细胞密度）;（c）相对能量成本，即，线粒体含量我们预测，自然的信息速率不同的渠道和“低速率”的渠道使用更少的空间和能量每比特强烈。 注意到OFF通道在空间上比ON通道更精细和更密集，并且“蓝/黄”通道也发生在两个空间尺度上，我们假设感受野大小和采样率被调谐到自然场景中的信息分布。为了测试这一点，AIM 2将在与已知感受野相对应的尺度上测量自然图像中的非彩色和彩色信息。我们预测，在自然界中，暗区占据更高的空间频率，每个视网膜区域比亮区包含更多的信息，因此需要更精细的通道和更多的突触;蓝色/黄色通道也有类似的预测。注意到通过视网膜的信息传递依赖于“带状”突触，我们假设它们以非常高的速率释放和检索囊泡。为了测试这一点，AIM 3将测量锥体突触的释放速率（FM 1 -43染料的双光子+电子显微镜），AIM 4将测量双极突触的速率（铁蛋白的电生理学+ EM）。 青光眼是致盲的主要原因之一，其原因既有神经节细胞缺氧，也有轴突运输减少。我们的研究将把神经节细胞信号传导与氧化能力和轴突运输能力联系起来，从而为未来的临床研究奠定基础。