Direct current electrical conduction block of peripheral nerve

Abstract

Electrical currents can be used to produce a block of action potential conduction in whole nerves. This block has a rapid onset and reversal. The mechanism of electrical nerve conduction block has not been conclusively determined, and inconsistencies appear in the literature regarding whether the block is produced by membrane hyperpolarization, depolarization, or through some other means. We have used simulations in a nerve membrane model, coupled with in vivo experiments, to identify the mechanism and principles of electrical conduction block. A nerve simulation package (Neuron) was used to model direct current (dc) block in squid, frog, and mammalian neuron models. A frog sciatic nerve/gastrocnemius preparation was used to examine nerve conduction block in vivo. Both simulations and experiments confirm that depolarization block requires less current than hyperpolarization block. Dynamic simulations suggest that block can occur under both the real physical electrode as well as adjacent virtual electrode sites. A hypothesis is presented which formulates the likely types of dc block and the possible block current requirements. The results indicate that electrical currents generally produce a conduction block due to depolarization of the nerve membrane, resulting in an inactivation of the sodium channels.

Nanomaterials for Neural Interfaces

“…This polarization inhibits and ultimately blocks the propagation of action potential spikes. [476][477][478] These results show that the NW/neurite junctions can be used beyond simple recording and stimulation, and enable more subtle modulation of the spike propagation. It should be possible to extend this approach to modulation of dendritic signals at the level of individual dendrites.…”

Action potential block in neurons by infrared light

“…However, electrical block requires either invasive and direct-contact electrodes or suffers from nonspecificity. 10,11 Pharmacological means of AP block suffer from nonspecificity and potential off-target effects. 12 Optogenetic means of AP block, such as by halorhodopsins, light-activated chloride ion channels, require genetic manipulation of the target cells.…”

A Simulation Study of the Combined Thermoelectric Extracellular Stimulation of the Sciatic Nerve of the Xenopus Laevis: The Localized Transient Heat Block

“…Reversible blocking of nerve conduction in targeted structures can be achieved by using various stimulation schemes based on direct currents (e.g. DC monophasic waveforms [5]) or high frequency alternating currents (HFAC) [6]. Several recent studies have examined the biophysics of HFAC techniques in both myelinated and unmyelinated fibres, optimal electrode design and optimal waveforms [7][8].…”