CIRCUITRY OF THE MIDGET AND PARASOL RECEPTIVE FIELD

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 这个项目的目标是确定感受野环绕是如何在神经节细胞水平上建立的，以及环绕如何通过识别周围的视锥输入来对颜色编码做出贡献。突触前假说认为，视锥细胞双极中心-环绕组织的形成是视锥细胞对抗的关键部位。我们首次在哺乳动物视网膜中展示了锥体双极细胞具有与神经节细胞相当的强大的中心-周围组织。然后，我们进行了一系列实验，试图选择性地阻断神经节细胞周围。我们发现，在阳伞细胞中，钴或缝隙连接阻滞剂Carbenoxolone选择性地减少了周围的拮抗作用。我们现在正在使用这些药物来评估一些神经节细胞类中感受野周围对颜色对抗的贡献。在第二系列实验中，我们开发了一种新的刺激方案来测量L、M和S视锥输入到侏儒和伞状神经节细胞周围的感受野的强度和符号。具体的目标是评估视锥信号权重在从视网膜外回路传输到视网膜内回路的过程中可能发生的变化。我们发现，从水平双极细胞水平到神经节细胞周围，突触增益没有变化，并得出结论，突触增益的锥体类型特定变化不是产生颜色对抗信号的可能机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The goal of this project is determine how the receptive field surround is established at the level of the ganglion cell and how the surround contributes to color-coding by identifying the cone inputs to the surround. The presynaptic hypothesis predicts that the creation of the cone bipolar center-surround organization is the critical locus for cone opponency. We showed for the first time in a mammalian retina that cone bipolar cells have robust center-surround organization comparable to their ganglion cell counterparts. We then undertook a series of experiments to attempt to selectively block ganglion cell surrounds. We found, in parasol cells, that either cobalt or the gap-junction blocker, carbenoxolone, selectively reduces surround antagonism. We are now using these drugs to assess the receptive field surround contribution to color-opponency in a number of ganglion cell classes. In a second series of experiments, we developed a new stimulus protocol to measure the strength and sign of L, M and S-cone inputs to the receptive field surrounds of midget and parasol ganglion cell types. The specific goal was to assess how cone signal weighting may be altered during transmission from outer to inner retinal circuitry. We showed that there are no gain changes from the horizontal-bipolar cell level to the ganglion cell surround and concluded that cone type-specific changes in synaptic gain are not a likely mechanism for generating color-opponent signals.