Magnetic and electrical stimulation of undulating nerve fibres: a simulation study

Schnabel, Veit; Struijk, Johannes

doi:10.1007/bf02513371

Cited by 26 publications

(26 citation statements)

References 26 publications

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“…The results showing the influence of the undulation amplitude and the wavelength on the excitation threshold described in this paper axe comparable with the results obtained by Schnabel and Struijk (SCHNABEL and STRUIJK, 1999;STRUIJK and SCHNABEL, 2000), although they used a point electrode.…”

Section: Discussionsupporting

confidence: 92%

“…had the same distance from the axis) and, for (I) = 0 and (I) = 0.5, they were placed asymmetrically to the central node. The values of the undulation parameters were adopted from the studies of other authors (HANINEC, 1986;SCHNABEL and STRUIJK, 1999) and from direct measurements from a Figure showing the peroneal nerve fibres in a rat. The reduced figure was published in SCHNABEL (2001).…”

Section: Nerve Fibre Modelmentioning

confidence: 99%

“…SCHNABEL and STRUIJK (1999) simulated the influence of nerve fibre undulation on the excitation threshold using electrical and magnetic nerve fibre stimulation. They used a dipole for electrical stimulation and showed that the excitation threshold depends on the undulation wavelength and the amplitude and that it can be either higher or lower than the excitation threshold of straight fibres.…”

Section: Introductionmentioning

confidence: 99%

“…SCHNABEL and STRUIJK (1999) developed a model to examine the influence of variable internodal length and nodal width on the excitation threshold. They showed that, depending on the internodal length and the electrode-fibre distance, the excitation threshold of a nerve fibre with variable intemodal length can be either higher or lower than the excitation threshold of a fibre with constant internodal length.…”

Section: Introductionmentioning

confidence: 99%

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Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study

Vučković

Struijk

Rijkhoff

2005

Med. Biol. Eng. Comput.

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The aim of the study was to investigate how variable fibre geometry influences the excitation and blocking threshold of an undulating peripheral nerve fibre. The sensitivity of the excitation and blocking thresholds of the nerve fibres to various geometric and stimulation parameters was examined. The nerve fibres had a spiral shape (defined by the undulation wavelength, undulation amplitude and phase), and the internodal length varied. Diameter-selective stimulation of nerve fibres was obtained using anodal block. Simulation was performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a model of a peripheral undulating human nerve fibre to simulate the fibre response to stimulation. The excitation threshold of the undulating fibres was up to 100% higher than the excitation threshold of the straight fibres. When a nerve was stimulated with long pulses, which are typically applied for anodal block (> 400 micros), the blocking threshold of the undulating fibres was up to four times higher than the blocking threshold of the straight fibres. Dependencies of the excitation threshold on geometric and stimulation parameters were the same as for a straight fibre. Dependencies of the blocking threshold on geometric and stimulation parameters were different compared with a straight fibre. Owing to the fibre undulation and variable internodal length, the blocking threshold and the minimum pulse duration to obtain anodal block were generally different in the proximal and distal directions. Owing to variable fibre geometry, the excitation threshold varied by up to +/- 40% of the mean value, and the blocking threshold varied by up to +/- 60 % of the mean value. Owing to undulation, the blocking threshold of large fibres could be higher than the blocking threshold of small-diameter fibres, even if they had the same geometry. The results indicate that, during skeletal muscle stretching and contracting or during variation in joint angle, the excitation and blocking thresholds of the nerve fibres change owing to variations in fibre geometry. A straight fibre model could be too simple for modelling the response of peripheral nerve fibres to electrical stimulation.

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Section: Discussionsupporting

confidence: 92%

Section: Nerve Fibre Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study

Vučković

Struijk

Rijkhoff

2005

Med. Biol. Eng. Comput.

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“…Other explanations for the experimental results would be obvious: tissue inhomogeneity around the nerve, undulation of nerve fibers within the nerve [4], and physiological and anatomical inhomogeneity of the fiber itself. However, the issue begs for a more profound analysis of the validity of the cable model in the case of strong transverse electric fields.…”

Section: Introductionmentioning

confidence: 99%

Difference between electrical and magnetic nerve stimulation: a case for the transverse field?

Struijk

Schnabel²

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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-The cable model for nerve activation is based, among other things, on the assumption of cylindrical symmetry. For the externally applied field in the case of electrical or magnetic stimulation the implication is that the transverse component of the field should be negligible. The present theoretical work shows that for electrical stimulation this assumption is valid in most of the cases, but for magnetic stimulation the assumption is not generally valid, although, with the note that this is strongly dependent on the resistivity of the perineurium of the nerve.

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The importance of axonal undulation in diffusion MR measurements: a Monte Carlo simulation study

et al. 2011

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Many axons follow wave-like undulating courses. This is a general feature of extracranial nerve segments, but is also found in some intracranial nervous tissue. The importance of axonal undulation has previously been considered, for example, in the context of biomechanics, where it has been shown that posture affects undulation properties. However, the importance of axonal undulation in the context of diffusion MR measurements has not been investigated. Using an analytical model and Monte Carlo simulations of water diffusion, this study compared undulating and straight axons in terms of diffusion propagators, diffusion-weighted signal intensities and parameters derived from diffusion tensor imaging, such as the mean diffusivity (MD), the eigenvalues and the fractional anisotropy (FA). All parameters were strongly affected by the presence of undulation. The diffusivity perpendicular to the undulating axons increased with the undulation amplitude, thus resembling that of straight axons with larger diameters. Consequently, models assuming straight axons for the estimation of the axon diameter from diffusion MR measurements might overestimate the diameter if undulation is present. FA decreased from approximately 0.7 to 0.5 when axonal undulation was introduced into the simulation model structure. Our results indicate that axonal undulation may play a role in diffusion measurements when investigating, for example, the optic and sciatic nerves and the spinal cord. The simulations also demonstrate that the stretching or compression of neuronal tissue comprising undulating axons alters the observed water diffusivity, suggesting that posture may be of importance for the outcome of diffusion MRI measurements.

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Magnetic and electrical stimulation of undulating nerve fibres: a simulation study

Cited by 26 publications

References 26 publications

Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study

Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study

Difference between electrical and magnetic nerve stimulation: a case for the transverse field?

The importance of axonal undulation in diffusion MR measurements: a Monte Carlo simulation study

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