The coupling between Ca²⁺ channels and release sensors is a key factor defining the signaling properties of a synapse. However, the coupling nanotopography at many synapses remains unknown, and it is unclear how it changes during development. To address these questions, we examined coupling at the cerebellar inhibitory basket cell (BC)-Purkinje cell (PC) synapse. Biophysical analysis of transmission by paired recording and intracellular pipette perfusion revealed that the effects of exogenous Ca²⁺ chelators decreased during development, despite constant reliance of release on P/Q-type Ca²⁺ channels. Structural analysis by freeze-fracture replica labeling (FRL) and transmission electron microscopy (EM) indicated that presynaptic P/Q-type Ca²⁺ channels formed nanoclusters throughout development, whereas docked vesicles were only clustered at later developmental stages. Modeling suggested a developmental transformation from a more random to a more clustered coupling nanotopography. Thus, presynaptic signaling developmentally approaches a point-to-point configuration, optimizing speed, reliability, and energy efficiency of synaptic transmission.

^{Ca 2+}通道和释放传感器之间的耦合是定义突触信号传导特性的关键因素。然而，许多突触的耦合纳米形貌仍然未知，也不清楚它在发育过程中如何变化。为了解决这些问题，我们检查了小脑抑制篮细胞 (BC)-浦肯野细胞 (PC) 突触的耦合。通过配对记录和细胞内移液管灌注对传输进行的生物物理分析表明，尽管外源性 Ca ²⁺螯合剂的释放始终依赖于 P/Q 型 Ca 2+ 通道，但在发育过程中外源性 Ca ²⁺螯合剂的作用有所减弱。通过冷冻断裂复制标记（FRL）和透射电子显微镜（EM）进行的结构分析表明，突触前P/Q型Ca ²⁺通道在整个发育过程中形成纳米簇，而对接的囊泡仅在发育后期聚集。建模表明从更随机的耦合纳米形貌到更聚集的耦合纳米形貌的发展转变。因此，突触前信号传导逐渐接近点对点配置，优化突触传输的速度、可靠性和能量效率。