Ribbon synapses compute temporal contrast and encode luminance in retinal rod bipolar cells.
Ribbon synapses compute temporal contrast and encode luminance in retinal rod bipolar cells.
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DOI：
10.1038/nn.2945
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发表时间：
2011-10-23
影响因子：
25
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整个神经系统都会计算对比度，以便高效地对变化的输入进行编码。视网膜在广泛的视觉条件下对亮度和对比度进行编码，因此必须调整其反应，以保持敏感度并避免饱和。在这里，我们展示了一种类型的适应如何允许单个突触计算对比度并编码对光线水平阶跃变化的双相反应中的亮度。光诱发的大鼠视网膜视杆双极细胞(RBC)突触可释放囊泡池(RRP)的耗尽限制了可用于编码瞬时但不是持续反应的动态范围，从而允许瞬时和持续释放分量分别计算时间对比度和编码平均光水平。释放/补充模型表明，单个、均一的突触小泡池足以产生这种行为，并揭示了形成双相对比度/亮度反应的主要机制是RRP的部分耗尽。
Contrast is computed throughout the nervous system to encode changing inputs efficiently. The retina encodes luminance and contrast over a wide range of visual conditions and so must adapt its responses to maintain sensitivity and avoid saturation. Here we show how one type of adaptation allows individual synapses to compute contrast and encode luminance in biphasic responses to step changes in light levels. Light-evoked depletion of the readily releasable vesicle pool (RRP) at rod bipolar cell (RBC) ribbon synapses in rat retina limits the dynamic range available to encode transient but not sustained responses, thereby allowing the transient and sustained components of release to compute temporal contrast and encode mean light levels, respectively. A release/replenishment model shows that a single, homogeneous pool of synaptic vesicles is sufficient to generate this behavior and reveals that the dominant mechanism shaping the biphasic contrast/luminance response is the partial depletion of the RRP.