Distinct synaptic transfer functions in same-type photoreceptors.
Distinct synaptic transfer functions in same-type photoreceptors.
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DOI：
10.7554/elife.67851
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发表时间：
2021-07-16
期刊：
影响因子：
7.7
通讯作者：
Baden T
中科院分区：
文献类型：
--
作者：
Schröder C;Oesterle J;Berens P;Yoshimatsu T;Baden T
许多感觉系统使用带状突触将其信号传输到下游电路。这种突触传递的性质从根本上决定了原始刺激中的哪些方面将被加强或抑制，从而部分地定义了电路的检测极限。因此，感觉神经元已经进化出各种各样的带状几何形状和囊泡池特性，以最好地支持其不同的功能需求。然而，对不同突触功能的需求不仅出现在神经元类型之间，而且也出现在神经元内部。在这里，我们表明，紫外线锥，一种类型的感光器的幼虫斑马鱼的眼睛，表现出显着的差异，其突触超微结构和随之而来的钙谷氨酸盐转移功能取决于它们在眼睛中的位置。我们得出这一结论，结合连续切片电子显微镜和同时的“双色”双光子成像的钙和谷氨酸信号从同一突触在体内。我们进一步使用函数数据集来拟合具有不同囊泡池大小、传输速率和其他突触特性的带状突触的级联模型。利用最近的发展，基于模拟的推理，我们获得完整的后验估计的参数，并比较这些在不同的视网膜区域。该模型使我们能够外推到新的刺激，并系统地研究不同的反应行为的各种带状配置。我们还提供了一个交互式的，易于使用的版本，这个模型作为一个在线工具。总的来说，我们表明，已经在单神经元类型的突触水平上存在高度专门化的机制，这是有利于不同的视觉功能的编码。
Many sensory systems use ribbon-type synapses to transmit their signals to downstream circuits. The properties of this synaptic transfer fundamentally dictate which aspects in the original stimulus will be accentuated or suppressed, thereby partially defining the detection limits of the circuit. Accordingly, sensory neurons have evolved a wide variety of ribbon geometries and vesicle pool properties to best support their diverse functional requirements. However, the need for diverse synaptic functions does not only arise across neuron types, but also within. Here we show that UV-cones, a single type of photoreceptor of the larval zebrafish eye, exhibit striking differences in their synaptic ultrastructure and consequent calcium to glutamate transfer function depending on their location in the eye. We arrive at this conclusion by combining serial section electron microscopy and simultaneous ‘dual-colour’ two-photon imaging of calcium and glutamate signals from the same synapse in vivo. We further use the functional dataset to fit a cascade-like model of the ribbon synapse with different vesicle pool sizes, transfer rates, and other synaptic properties. Exploiting recent developments in simulation-based inference, we obtain full posterior estimates for the parameters and compare these across different retinal regions. The model enables us to extrapolate to new stimuli and to systematically investigate different response behaviours of various ribbon configurations. We also provide an interactive, easy-to-use version of this model as an online tool. Overall, we show that already on the synaptic level of single-neuron types there exist highly specialised mechanisms which are advantageous for the encoding of different visual features.