Significant anisotropic neuronal refractory period plasticity

TL;DR

This study reveals that neuronal refractory periods can be significantly extended through activity-dependent plasticity, primarily originating in dendrites, which impacts network dynamics and neuronal response timing.

Contribution

It demonstrates for the first time that neuronal absolute refractory periods are highly plastic and can be modulated by preceding activity, with a focus on dendritic origins.

Findings

ARP increases with stimulation frequency

ARP saturates at the response latency phase

Preceding intracellular stimulations do not affect ARP

Abstract

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.