Circadian Plasticity in Photoreceptor Cells Controls Visual Coding Efficiency in Drosophila melanogaster
Circadian Plasticity in Photoreceptor Cells Controls Visual Coding Efficiency in Drosophila melanogaster
复制标题
DOI：
10.1371/journal.pone.0009217
复制
发表时间：
2010-02-15
期刊：
影响因子：
3.7
通讯作者：
Strauss, Roland
中科院分区：
文献类型：
--
作者：
Barth, Martin;Schultze, Michael;Strauss, Roland
在黑腹果蝇中，第一视神经纤维网或视神经层突触末梢的神经元可塑性取决于羽化后关键时期内的早期视觉体验[1]。目前的研究揭示了这种类型的突触末端可塑性涉及两种额外的并行机制。首先，内源性昼夜节律导致感光细胞末梢体积的日常振荡。其次，日常视觉体验精确调节感光细胞末梢所经历的昼夜节律时间进程和体积振荡幅度。两种机制在其分子基础上是可分离的。我们认为，所描述的果蝇神经元可塑性确保了视觉系统在 24 小时内持续保持最佳性能。此外，果蝇的感觉系统不仅可以解释可预测的环境变化，还可以解释急剧的环境变化。感光细胞突触末端的体积变化伴随着突触前带的昼夜节律和光诱导变化以及上皮神经胶质细胞向感光细胞末端的延伸，这表明视觉暴露和生物钟都改变了层的结构。时钟突变分析和所有 R1-6 细胞中 PER 蛋白节律的拯救表明，感光细胞可塑性是自主的，足以控制视觉行为。当在低光水平下引发时，视觉引导行为的强度，即视运动转动反应，与感光细胞的突触末端体积振荡共同变化。我们的结果表明，视觉信息的行为相关自适应处理部分是在视觉输入水平上进行的。
In the fly Drosophila melanogaster, neuronal plasticity of synaptic terminals in the first optic neuropil, or lamina, depends on early visual experience within a critical period after eclosion [1]. The current study revealed two additional and parallel mechanisms involved in this type of synaptic terminal plasticity. First, an endogenous circadian rhythm causes daily oscillations in the volume of photoreceptor cell terminals. Second, daily visual experience precisely modulates the circadian time course and amplitude of the volume oscillations that the photoreceptor-cell terminals undergo. Both mechanisms are separable in their molecular basis. We suggest that the described neuronal plasticity in Drosophila ensures continuous optimal performance of the visual system over the course of a 24 h-day. Moreover, the sensory system of Drosophila cannot only account for predictable, but also for acute, environmental changes. The volumetric changes in the synaptic terminals of photoreceptor cells are accompanied by circadian and light-induced changes of presynaptic ribbons as well as extensions of epithelial glial cells into the photoreceptor terminals, suggesting that the architecture of the lamina is altered by both visual exposure and the circadian clock. Clock-mutant analysis and the rescue of PER protein rhythmicity exclusively in all R1-6 cells revealed that photoreceptor-cell plasticity is autonomous and sufficient to control visual behavior. The strength of a visually guided behavior, the optomotor turning response, co-varies with synaptic-terminal volume oscillations of photoreceptor cells when elicited at low light levels. Our results show that behaviorally relevant adaptive processing of visual information is performed, in part, at the level of visual input level.