Essential role of axonal VGSC inactivation in time-dependent deceleration and unreliability of spike propagation at cerebellar Purkinje cells

Abstract

BackgroundThe output of the neuronal digital spikes is fulfilled by axonal propagation and synaptic transmission to influence postsynaptic cells. Similar to synaptic transmission, spike propagation on the axon is not secure, especially in cerebellar Purkinje cells whose spiking rate is high. The characteristics, mechanisms and physiological impacts of propagation deceleration and infidelity remain elusive. The spike propagation is presumably initiated by local currents that raise membrane potential to the threshold of activating voltage-gated sodium channels (VGSC).ResultsWe have investigated the natures of spike propagation and the role of VGSCs in this process by recording spikes simultaneously on the somata and axonal terminals of Purkinje cells in cerebellar slices. The velocity and fidelity of spike propagation decreased during long-lasting spikes, to which the velocity change was more sensitive than fidelity change. These time-dependent deceleration and infidelity of spike propagation were improved by facilitating axonal VGSC reactivation, and worsen by intensifying VGSC inactivation.ConclusionOur studies indicate that the functional status of axonal VGSCs is essential to influencing the velocity and fidelity of spike propagation.

Voltage-independent sodium channels emerge for an expression of activity-induced spontaneous spikes in GABAergic neurons

“…dV/dt values well represent VGSCs’ efficiency in their synchronous activation [59]. However, as two rising phases of AISS spikes are present, the spike duration at half-height includes the mixture of the two components, i.e., this parameter is influenced by two separate mechanisms.…”

Virus-Induced Gene Silencing Identifies an Important Role of the TaRSR1 Transcription Factor in Starch Synthesis in Bread Wheat

“…AGPase catalyzes adenosine diphosphate glucose (ADP-Glc) to glucose-1-phosphate (G-1-P) and provides substrates for amylose and amylopectin synthesis. GBSS is a key enzyme involved in amylose synthesis, whereas SS, BE, and DBE function together with distinct roles to catalyze amylopectin synthesis [2,3]. In starch biosynthesis, PHO and DPE are believed to be involved in the initiation steps, elongating α-1,4-linked glucan polymers using G-1-P as substrate, although their precise mechanisms remain unclear [2,4].…”

Activity-induced spontaneous spikes in GABAergic neurons suppress seizure discharges: an implication of computational modeling

“…in various intensities were injected into these interneurons to induce the sequential spikes. In evaluating their ability of firing spikes, we measured the initiation of spikes by weak depolarization that was thought as neuronal sensitivity to excitatory inputs, i.e., neuronal ability to convert synaptic signals into spikes [33–36]. …”