Functional elimination of excitatory feedforward inputs underlies developmental refinement of visual receptive fields in zebrafish.
Functional elimination of excitatory feedforward inputs underlies developmental refinement of visual receptive fields in zebrafish.
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DOI：
10.1523/jneurosci.6220-10.2011
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发表时间：
2011-04-06
期刊：
影响因子：
--
通讯作者：
Tao HW
中科院分区：
文献类型：
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作者：
Zhang M;Liu Y;Wang SZ;Zhong W;Liu BH;Tao HW
在许多感觉系统中，由锋电位反应测量的感受野（RF）在发育过程中经历渐进的细化。已经提出，消除兴奋性突触输入是这种功能细化的基础。然而，尽管有许多细胞外记录和解剖学研究，直接在体内细胞内的证据仍然有限。本研究通过对发育中的斑马鱼视顶盖进行细胞贴附记录，发现在视网膜顶盖突触最初形成后的短时间内，顶盖神经元的棘波视觉射频经历了两个阶段的发育调制：从最初的扩展到后来的细化。全细胞电压钳记录显示，潜在的兴奋性突触RF表现出类似的发展进程，其空间范围先增加，然后减少，其空间调谐轮廓逐渐尖锐。抑制性RF最初大于兴奋性RF，但在后期与兴奋性RF匹配。与集成和消防神经元模型的模拟表明，兴奋性RF的发展变化主要占的尖峰RF的最初扩大和后来的细化，而抑制性输入一般减少尖峰RF的大小，而不影响其发展进程。此外，单个视网膜神经节细胞（RGC）的棘波RF在同一时期的大小没有显着变化，顶盖兴奋性RF的空间范围和调谐配置文件几乎没有改变后，顶盖内兴奋性连接沉默。总之，我们的研究结果表明，顶盖视觉RFs的功能完善的结果主要是从选择性消除前馈retinotectal输入。
In many sensory systems, receptive fields (RFs) measured by spike responses undergo progressive refinement during development. It has been proposed that elimination of excitatory synaptic inputs underlies such functional refinement. However, despite many extracellular recording and anatomical studies, direct in vivo intracellular evidence has remained limited. In this study, by cell-attached recordings in the developing optic tectum of zebrafish, we found that during a short period after the initial formation of retinotectal synapses, spike visual RFs of tectal neurons underwent a two-stage developmental modulation: from an initial expansion to a later refinement. Whole-cell voltage-clamp recordings revealed that the underlying excitatory synaptic RF exhibited a similar developmental progression with its spatial extent first increased and then reduced, and its spatial tuning profile gradually sharpened. The inhibitory RF was initially larger than the excitatory RF, but became matched with the excitatory RF at later stages. Simulation with the integrate-and-fire neuron model suggested that the developmental changes of excitatory RFs primarily accounted for the initial enlargement and later refinement of spike RFs, while inhibitory inputs generally reduced the size of the spike RF without affecting its developmental progression. In addition, spike RF of individual retinal ganglion cells (RGCs) did not significantly change in size during the same period, and the spatial extent and tuning profile of the tectal excitatory RF barely changed after intratectal excitatory connections were silenced. Together, our results demonstrate that the functional refinement of tectal visual RFs results primarily from a selective elimination of feedforward retinotectal inputs.