School of Biosciences, The University of Melbourne, Melbourne, Australia.
Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia.
Sci Rep. 2019 Dec 12;9(1):18931. doi: 10.1038/s41598-019-54958-6.
The zebrafish (Danio rerio) is a popular vertebrate model for studying visual development, especially at the larval stage. For many vertebrates, post-natal visual experience is essential to fine-tune visual development, but it is unknown how experience shapes larval zebrafish vision. Zebrafish swim with a moving texture; in the wild, this innate optomotor response (OMR) stabilises larvae in moving water, but it can be exploited in the laboratory to assess zebrafish visual function. Here, we compared spatial-frequency tuning inferred from OMR between visually naïve and experienced larvae from 5 to 7 days post-fertilisation. We also examined development of synaptic connections between neurons by quantifying post-synaptic density 95 (PSD-95) in larval retinae. PSD-95 is closely associated with N-methyl-D-aspartate (NMDA) receptors, the neurotransmitter-receptor proteins underlying experience-dependent visual development. We found that rather than following an experience-independent genetic programme, developmental changes in visual spatial-frequency tuning at the larval stage required visual experience. Exposure to motion evoking OMR yielded no greater improvement than exposure to static form, suggesting that increased sensitivity as indexed by OMR was driven not by motor practice but by visual experience itself. PSD-95 density varied with visual sensitivity, suggesting that experience may have up-regulated clustering of PSD-95 for synaptic maturation in visual development.
斑马鱼（Danio rerio）是研究视觉发育的一种常用脊椎动物模型，尤其是在幼体阶段。对于许多脊椎动物来说，出生后的视觉经验对于微调视觉发育至关重要，但尚不清楚经验如何塑造幼体斑马鱼的视力。斑马鱼在移动的纹理中游泳；在野外，这种先天的光流反应（OMR）可以使游动的幼虫保持稳定，但它可以在实验室中被利用来评估斑马鱼的视觉功能。在这里，我们比较了从受精后 5 到 7 天的未经视觉经验的和有经验的幼体的 OMR 推断出的空间频率调谐。我们还通过量化幼鱼视网膜中的突触后密度 95（PSD-95）来检查神经元之间突触连接的发育。PSD-95 与 N-甲基-D-天冬氨酸（NMDA）受体密切相关，NMDA 受体是经验依赖性视觉发育的神经递质受体蛋白。我们发现，视觉空间频率调谐在幼体阶段的发育变化不是遵循独立于经验的遗传程序，而是需要视觉经验。引发 OMR 的运动暴露并没有比静态形式的暴露产生更大的改善，这表明 OMR 所指示的敏感性增加不是由运动练习驱动的，而是由视觉经验本身驱动的。PSD-95 密度随视觉敏感性而变化，这表明经验可能上调了 PSD-95 的聚类，以促进视觉发育中的突触成熟。
