Center for Neural Science, New York University, New York, NY, USA.
Institut de l'Audition, Institut Pasteur, Paris, France.
Nat Commun. 2019 Sep 3;10(1):3969. doi: 10.1038/s41467-019-11851-0.
Analyses of idealized feedforward networks suggest that several conditions have to be satisfied in order for activity to propagate faithfully across layers. Verifying these concepts experimentally has been difficult owing to the vast number of variables that must be controlled. Here, we cultured cortical neurons in a chamber with sequentially connected compartments, optogenetically stimulated individual neurons in the first layer with high spatiotemporal resolution, and then monitored the subthreshold and suprathreshold potentials in subsequent layers. Brief stimuli delivered to the first layer evoked a short-latency transient response followed by sustained activity. Rate signals, carried by the sustained component, propagated reliably through 4 layers, unlike idealized feedforward networks, which tended strongly towards synchrony. Moreover, temporal jitter in the stimulus was transformed into a rate code and transmitted to the last layer. This novel mode of propagation occurred in the balanced excitatory-inhibitory regime and is mediated by NMDA-mediated receptors and recurrent activity.
对理想化前馈网络的分析表明，为了使活动能够在层间准确地传播，需要满足几个条件。由于必须控制大量变量，因此实验验证这些概念一直很困难。在这里，我们在一个具有顺序连接隔室的腔室中培养皮质神经元，用光遗传方法以高时空分辨率刺激第一层中的单个神经元，然后监测随后各层的亚阈和阈上电位。在第一层施加短暂刺激会引发短潜伏期瞬态反应，随后是持续活动。由持续成分携带的速率信号可靠地通过 4 层传播，与理想化的前馈网络不同，后者强烈倾向于同步。此外，刺激中的时间抖动被转换为速率码并传输到最后一层。这种新的传播模式发生在平衡的兴奋性-抑制性状态下，由 NMDA 介导的受体和复发性活动介导。
