Refractory periods are an unavoidable feature of excitable elements, resulting in necessary time-lags for re-excitation. Herein, we measure neuronal absolute refractory periods (ARPs) in synaptic blocked neuronal cultures. In so doing, we show that their duration can be significantly extended by dozens of milliseconds using preceding evoked spikes generated by extracellular stimulations. The ARP increases with the frequency of preceding stimulations, and saturates at the intermittent phase of the neuronal response latency, where a short relative refractory period might appear. Nevertheless, preceding stimulations via a different extracellular route does not affect the ARP. It is also found to be independent of preceding intracellular stimulations. All these features strongly suggest that the anisotropic ARPs originate in neuronal dendrites. The results demonstrate the fast and significant plasticity of the neuronal ARP, depending on the firing activity of its connecting neurons, which is expected to affect network dynamics.

不应期是可激发元素不可避免的特征，导致重新激发所需的时间滞后。在此，我们测量了突触受阻神经元培养物中的神经元绝对不应期 (ARPs)。在这样做时，我们表明它们的持续时间可以使用由细胞外刺激产生的先前诱发尖峰显着延长数十毫秒。ARP 随先前刺激的频率而增加，并在神经元反应潜伏期的间歇期饱和，此时可能出现较短的相对不应期。然而，通过不同的细胞外途径进行的先前刺激不会影响 ARP。还发现它不依赖于先前的细胞内刺激。所有这些特征强烈表明各向异性 ARPs 起源于神经元树突。