Zbili Mickaël, Rama Sylvain, Yger Pierre, Inglebert Yanis, Boumedine-Guignon Norah, Fronzaroli-Moliniere Laure, Brette Romain, Russier Michaël, Debanne Dominique
UNIS, INSERM, UMR 1072, Aix-Marseille Université, 13015, Marseille, France.
Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France.
Sci Adv. 2020 May 6;6(19):eaay4313. doi: 10.1126/sciadv.aay4313. eCollection 2020 May.
Sensory processing requires mechanisms of fast coincidence detection to discriminate synchronous from asynchronous inputs. Spike threshold adaptation enables such a discrimination but is ineffective in transmitting this information to the network. We show here that presynaptic axonal sodium channels read and transmit precise levels of input synchrony to the postsynaptic cell by modulating the presynaptic action potential (AP) amplitude. As a consequence, synaptic transmission is facilitated at cortical synapses when the presynaptic spike is produced by synchronous inputs. Using dual soma-axon recordings, imaging, and modeling, we show that this facilitation results from enhanced AP amplitude in the axon due to minimized inactivation of axonal sodium channels. Quantifying local circuit activity and using network modeling, we found that spikes induced by synchronous inputs produced a larger effect on network activity than spikes induced by asynchronous inputs. Therefore, this input synchrony-dependent facilitation may constitute a powerful mechanism, regulating synaptic transmission at proximal synapses.
感觉处理需要快速重合检测机制来区分同步输入和异步输入。动作电位阈值适应能够实现这种区分，但在将该信息传递到网络方面效率低下。我们在此表明，突触前轴突钠通道通过调节突触前动作电位（AP）幅度，读取并向突触后细胞传递精确的输入同步水平。因此，当突触前动作电位由同步输入产生时，皮质突触处的突触传递会得到促进。通过双体细胞 - 轴突记录、成像和建模，我们表明这种促进作用源于轴突钠通道失活最小化导致轴突中动作电位幅度增强。通过量化局部回路活动并使用网络建模，我们发现同步输入诱导的动作电位对网络活动产生的影响比异步输入诱导的动作电位更大。因此，这种依赖输入同步的促进作用可能构成一种强大的机制，调节近端突触处的突触传递。
