Department of Neurology, Jena University Hospital, Jena, Germany.
Section Translational Neuroimmunology, Jena University Hospital, Jena, Germany.
Elife. 2022 Dec 19;11:e82756. doi: 10.7554/eLife.82756.
Spontaneous correlated activity is a universal hallmark of immature neural circuits. However, the cellular dynamics and intrinsic mechanisms underlying network burstiness in the intact developing brain are largely unknown. Here, we use two-photon Ca imaging to comprehensively map the developmental trajectories of spontaneous network activity in the hippocampal area CA1 of mice in vivo. We unexpectedly find that network burstiness peaks after the developmental emergence of effective synaptic inhibition in the second postnatal week. We demonstrate that the enhanced network burstiness reflects an increased functional coupling of individual neurons to local population activity. However, pairwise neuronal correlations are low, and network bursts (NBs) recruit CA1 pyramidal cells in a virtually random manner. Using a dynamic systems modeling approach, we reconcile these experimental findings and identify network bi-stability as a potential regime underlying network burstiness at this age. Our analyses reveal an important role of synaptic input characteristics and network instability dynamics for NB generation. Collectively, our data suggest a mechanism, whereby developing CA1 performs extensive input-discrimination learning prior to the onset of environmental exploration.
自发性相关活动是未成熟神经回路的普遍特征。然而，完整发育中的大脑中网络突发的细胞动力学和内在机制在很大程度上尚不清楚。在这里，我们使用双光子 Ca 成像技术全面绘制了体内小鼠海马区 CA1 中自发网络活动的发育轨迹。我们出人意料地发现，网络突发的突发性在第二产后周有效突触抑制出现后达到峰值。我们证明，增强的网络突发反映了个体神经元与局部群体活动的功能耦合增强。然而，成对神经元相关性较低，网络突发（NB）以几乎随机的方式招募 CA1 锥体神经元。使用动态系统建模方法，我们协调了这些实验结果，并确定网络双稳定性作为该年龄段网络突发的潜在状态。我们的分析揭示了突触输入特性和网络不稳定性动力学对 NB 产生的重要作用。总的来说，我们的数据表明，在环境探索开始之前，CA1 正在进行广泛的输入判别学习。
