During postnatal development of the visual cortex between eye-opening to puberty, visual experience promotes a gradual increase in the strength of inhibitory synaptic connections from parvalbumin-positive interneurons (PV-INs) onto layer 2/3 pyramidal cells. However, the detailed connectivity properties and molecular mechanisms underlying these developmental changes are not well understood. Using dual-patch clamp in brain slices from G42 mice, we revealed that both connection probability and the number of synaptic release sites contributed to the enhancement of synaptic strength. The increase of release site number was hindered by dark rearing from eye-opening and rescued by 3-days re-exposure to the normal visual environment. The effect of light re-exposure on restoring synaptic release sites in dark reared mice was mimicked by the agonist of cannabinoid-1 (CB1) receptors and blocked by an antagonist of these receptors, suggesting a role for endocannabinoid signaling in light-induced maturation of inhibitory connectivity from PV-INs to pyramidal cells during postnatal development.

在睁大眼睛到青春期之间的视觉皮层的产后发育过程中，视觉体验会促进从小白蛋白阳性中间神经元（PV-IN）到第2/3层锥体细胞的抑制性突触连接的强度逐渐增加。但是，这些发展变化背后的详细的连接属性和分子机制还没有很好的理解。在G42小鼠的脑切片中使用双膜钳，我们发现连接概率和突触释放位点的数量均有助于突触强度的增强。睁开眼睛的黑暗饲养阻碍了释放部位数量的增加，并通过三天的再次暴露于正常视觉环境而得以挽救。