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

Abstract

. A simulation study of the combined thermoelectric extracellular stimulation of the sciatic nerve of the Xenopus laevis: the localized transient heat block. IEEE Transactions on Biomedical Engineering, 59(6), pp. 1758 -1769 . doi: 10.1109 /TBME.2012 This is the accepted version of the paper.This version of the publication may differ from the final published version. 1  Abstract-This paper presents the response of the Xenopus laevis nerve fibers to combinations of electrical (cuff electrodes) and optical (infrared laser, low power sub-5mW) stimulation. Assuming that the main effect of the laser irradiation on the nerve tissue is the localized temperature increase, this paper analyzes and gives new insights into the function of the combined thermoelectric stimulation on both excitation and blocking of the nerve action potentials (AP). The calculations involve a finite-element model (COMSOL) to represent the electrical properties of the nerve and cuff. Electric field distribution along the nerve was computed for the given stimulation current profile and imported into a NEURON model, which was built to simulate the electrical behavior of myelinated nerve fiber under extracellular stimulation. The main result of this study of combined thermoelectric stimulation showed that local temperature increase, for the given electric field, can create a transient block of both the generation and propagation of the APs. Some preliminary experimental data in support of this conclusion are also shown. Permanent

Hybrid electro-optical stimulation of the rat sciatic nerve induces force generation in the plantarflexor muscles

“…We previously observed that increasing the infrared radiant exposure beyond a certain threshold will result in reversible inhibition of neural activity (17). Recent modeling studies demonstrated that this is due to non-uniform rate increases in the temperature-dependent Hodgkin-Huxley gating mechanisms (28). No inhibition was observed during this current study; however, reduction in evoked force with further increases in radiant exposure may occur.…”

Differential responses to high-frequency electrical stimulation in ON and OFF retinal ganglion cells

“…Recently, it has been shown that when high-frequency pulse trains are applied to a peripheral axon bundle, the amplitude and frequency can be tuned to induce a selective conduction block in certain fibers: relatively low stimulation rates selectively blocked activity in myelinated fibers while non-myelinated fibers were unaffected, while relatively high stimulation rates did the opposite – blocking activity in non-myelinated fibers while leaving myelinated fibers unaffected [34]. The mechanism through which the block occurs, as well as the reasons for its sensitivity to the rate of stimulation, both remain unknown, although theories involving activation and/or inactivation of several different ion channels have been proposed [35, 36]. Importantly, however, this work raises the possibility that HFS could selectively activate different types of neurons in the central nervous system as well.…”

Neuromodulation: present and emerging methods

“…Lines show the extracellular ( V e ) and membrane voltage ( V m = V i − V e , V i is intracellular voltage) at the nodes 1, 2, and 3 shown in (A) . For more details about the electrode-electrolyte model and the nerve model which is in this case Xenopus laevis sciatic nerve see Mou et al (2012). …”

“…The plasma membrane electrical capacitance is reversibly affected by the temperature ( dC m / dT term) because the total capacitance of a lipid membrane in electrolyte solution includes in-series capacitance of ionic double layers at the interface between the (polar) membrane surface and electrolyte (Shapiro et al, 2012). Conversely during slow heating the changes to ionic channels dominate and in particular changes to Na + and K + activation/deactivation dynamics prevent action potential initiation and propagation (Mou et al, 2012; Duke et al, 2013). Thermal damage to tissue is a major issue with this method of neuromodulation, especially for suppression due to the higher temperatures and slower, more diffuse heating necessary (Wells et al, 2007).…”

“…But effective stimulation and damage thresholds are within an order of magnitude for some neurons which is potentially a cause for concern (Richter et al, 2011). Laser induced heating has also been demonstrated for neural inhibition as part of a hybrid electrical stimulation/thermal inhibition device (Mou et al, 2012; Duke et al, 2013). …”