Intrinsic excitability mechanisms of neuronal ensemble formation

Neuronal ensembles are coactive groups of cortical neurons, found in spontaneous and evoked activity, that can mediate perception and behavior. To understand the mechanisms that lead to the formation of ensembles, we co-activated optogenetically and electrically layer 2/3 pyramidal neurons in brain slices from mouse visual cortex, in animals from both sexes, replicating in vitro an optogenetic protocol to generate ensembles in vivo. Using whole-cell and perforated patch-clamp pair recordings we find that, after optogenetic or electrical stimulation, coactivated neurons increase their correlation in spontaneous activity, a hallmark of ensemble formation. Coactivated neurons showed small biphasic changes in presynaptic plasticity, with an initial depression followed by a potentiation after a recovery period. Unexpectedly, optogenetic and electrical stimulation-induced significant increases in frequency and amplitude of spontaneous EPSPs, even after single-cell stimulation. In addition, we...

神经元集群（Neuronal ensembles）是一组同步激活的皮层神经元，可在自发放电与诱发放电活动中被观测到，能够介导感知与行为过程。为探究神经元集群形成的潜在机制，本研究对雌雄小鼠视觉皮层脑片的2/3层锥体神经元进行了光遗传联合电刺激，并在体外复现了此前用于在体诱导神经元集群的光遗传实验范式。通过全细胞膜片钳与穿孔膜片钳配对记录，我们发现：经光遗传或电刺激后，共同激活的神经元之间的自发放电相关性显著提升——这正是神经元集群形成的标志性特征。共同激活的神经元在突触前可塑性上呈现出小幅双相变化：初始阶段出现突触抑制，经过恢复期后则转为突触增强。出乎意料的是，无论光遗传刺激还是电刺激，甚至仅针对单个神经元的刺激，均能使自发兴奋性突触后电位（spontaneous excitatory postsynaptic potentials, EPSPs）的频率与幅值显著升高。此外，我们...