A spatiotemporal white noise analysis of photoreceptor responses to UV and green light in the dragonfly median ocellus.
A spatiotemporal white noise analysis of photoreceptor responses to UV and green light in the dragonfly median ocellus.
复制标题
光感受器对紫外线和绿光的瞬时白噪声分析。
DOI：
10.1085/jgp.200509319
复制
发表时间：
2005-11
影响因子：
3.8
通讯作者：
Stange, Gert
中科院分区：
文献类型：
--
作者：
van Kleef, Joshua;James, Andrew Charles;Stange, Gert
成年蜻蜓用三只简单的眼睛扩大它们的复眼，这三只眼睛被称为眼背部。虽然已知眼球系统在飞行过程中调节稳定的头反射，但眼球视网膜动态解析环境的能力尚不清楚。我们首次直接测量了蜻蜓中(中)眼窝感光细胞的角敏感度。我们对光适应的光感受器的细胞内记录进行了二阶Wiener核分析。在不同的环境温度下，用不同对比度的紫外光和绿光同时发出的一维水平或垂直图案来刺激这些信号。光感受器具有垂直和水平接受角分别为15°和28°的各向异性感受场。一阶(线性)时间核心包含显著的未及点，其幅度在刺激的对比度变化时不变，但在较高温度下显着降低。二阶核函数显示了两个不同的非线性成分：快速作用的自促进作用，它在紫外线中占主导地位，其次是紫外线和绿光反应的延迟自抑制和交叉抑制。没有发现紫外线和绿光之间的促进性相互作用，这表明绿色和紫外线反应的促进性发生在孤立的隔间。UV和绿色刺激之间存在抑制，表明抑制发生在UV和绿色反应途径的共同点。我们提出了一个具有初始阶段的非线性级联模型(NLN)，该模型由分开的紫外路径和绿色路径组成。每条通路都包含一个与线性响应相耦合的快速促进的非线性。线性响应用扩展的对数正态模型描述，考虑了相位分量。最终的非线性由UV和绿色通路中的自抑制和这些通路之间的抑制组成。该模型可以在很大程度上预测感光器对紫外线和绿光的反应。
Adult dragonflies augment their compound eyes with three simple eyes known as the dorsal ocelli. While the ocellar system is known to mediate stabilizing head reflexes during flight, the ability of the ocellar retina to dynamically resolve the environment is unknown. For the first time, we directly measured the angular sensitivities of the photoreceptors of the dragonfly median (middle) ocellus. We performed a second-order Wiener Kernel analysis of intracellular recordings of light-adapted photoreceptors. These were stimulated with one-dimensional horizontal or vertical patterns of concurrent UV and green light with different contrast levels and at different ambient temperatures. The photoreceptors were found to have anisotropic receptive fields with vertical and horizontal acceptance angles of 15° and 28°, respectively. The first-order (linear) temporal kernels contained significant undershoots whose amplitudes are invariant under changes in the contrast of the stimulus but significantly reduced at higher temperatures. The second-order kernels showed evidence of two distinct nonlinear components: a fast acting self-facilitation, which is dominant in the UV, followed by delayed self- and cross-inhibition of UV and green light responses. No facilitatory interactions between the UV and green light were found, indicating that facilitation of the green and UV responses occurs in isolated compartments. Inhibition between UV and green stimuli was present, indicating that inhibition occurs at a common point in the UV and green response pathways. We present a nonlinear cascade model (NLN) with initial stages consisting of separate UV and green pathways. Each pathway contains a fast facilitating nonlinearity coupled to a linear response. The linear response is described by an extended log-normal model, accounting for the phasic component. The final nonlinearity is composed of self-inhibition in the UV and green pathways and inhibition between these pathways. The model can largely predict the response of the photoreceptors to UV and green light.