DC-Evoked Modulation of Excitability of Myelinated Nerve Fibers and Their Terminal Branches; Differences in Sustained Effects of DC

Kaczmarek, Dominik; Jankowska, E.

doi:10.1016/j.neuroscience.2018.01.036

Cited by 16 publications

(25 citation statements)

References 49 publications

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“…At the level of the dorsal roots, the after‐effects were only marginal after 0.5–1 min of the conditioning nerve stimulation (30 or 60 Tib stimuli) but they became statistically significant following the subsequent 2 min period, that is, after 180 Tib stimuli at 1 Hz (Figure a). The increases in nerve volleys evoked by DR stimulation outlasting the conditioning peripheral nerve stimulation were comparable to those outlasting DC administration (Figure c), but both were of shorter duration than the post‐conditioning facilitation of effects of stimulation of the dorsal columns (Figure f) found using the same experimental procedures (Bączyk & Jankowska, ; Kaczmarek & Jankowska, ). We failed, on the other hand, to find post‐conditioning effects of 5 ms current pulses (Figure b) that would replicate effects of such pulses on the excitability of nerve fibres stimulated within the dorsal columns (Figure e).…”

Section: Resultsmentioning

confidence: 55%

“…(d–f) Increases in the excitability of epidurally stimulated nerve fibres found using similar experimental paradigms (replotted data from figs. 3 and 6 in (Bączyk & Jankowska, ; Kaczmarek & Jankowska, ). (g and h) Maximal increases in the excitability of fibres in the sciatic nerve during and after Tib stimulation (unpublished single series of data from (Bolzoni et al., ) as compared with those during and after DC administration.…”

Section: Resultsmentioning

confidence: 99%

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Ephaptic interactions between myelinated nerve fibres of rodent peripheral nerves

Bolzoni

Jankowska

2019

Eur J of Neuroscience

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We report evidence that ephaptic interactions may occur between intact mammalian myelinated nerve fibres and not only between demyelinated or damaged mammalian nerve fibres or nerve cells as analysed in previous studies. The ephaptic interactions were investigated between nerve fibres traversing the lumbar dorsal roots and between bundles of fibres in the sciatic nerve in anaesthetized rats in vivo. The interactions were estimated by comparing the excitability of nerve fibres originating from one of the hindlimb nerves (peroneal or sural) under control conditions and when the stimulation of these fibres was combined with stimulation of another nerve (tibial). An increase in nerve volleys recorded from group I muscle afferents in the peroneal nerve and of the fastest skin afferents in the sural nerve was used as a measure of the increase in the excitability. The excitability of these fibres was increased during a fraction of a millisecond, coinciding with the period of passage of nerve impulses evoked by the conditioning stimulation of the tibial nerve. The degree of the increase was comparable to the increases in the excitability evoked by 1–2 min lasting fibre polarization. Ephaptic interactions were found to be more potent and with longer lasting after‐effects within the dorsal roots than within the sciatic nerve. We postulate that ephaptic interactions may result in the synchronization of information forwarded via neighbouring afferent nerve fibres prior to their entry into the spinal cord and thereby securing the propagation of nerve impulses across branching points within the spinal grey matter.

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Section: Resultsmentioning

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Ephaptic interactions between myelinated nerve fibres of rodent peripheral nerves

Bolzoni

Jankowska

2019

Eur J of Neuroscience

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“…Changes in motoneuron threshold and firing properties are not restricted to the period coinciding with current application and can be observed for at least 15 min after the current offset (Bączyk, Drzymała‐Celichowska, Mrówczyński, & Krutki, ). Moreover, tsDCS effects appear to depend on the current orientation (Bączyk et al, ; Kaczmarek & Jankowska, ) and the effects of anodal polarization (when the active electrode is positive) and cathodal polarization (when the active electrode is negative) on intrinsic excitability and nerve fibre activity of motoneurons appear to differ without being exactly opposite (Bączyk et al, ; Bolzoni & Jankowska, ; Kaczmarek & Jankowska, ).…”

Section: Introductionmentioning

confidence: 99%

Long‐lasting modifications of motoneuron firing properties by trans‐spinal direct current stimulation in rats

Bączyk¹,

Drzymała‐Celichowska²,

Mrówczyński³

et al. 2019

Eur J of Neuroscience

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Trans-spinal direct current stimulation (tsDCS) is a novel neuromodulatory technique that has been used during neurological rehabilitation and sports to modulate muscle activation. However, the physiological mechanisms that underly the longlasting functional effects of polarization are not yet fully understood, nor are their relationships with specific neuronal populations. The acute facilitatory and depressive effects of anodal and cathodal polarization on motoneurons have been recently demonstrated, and the aim of this study was to determine whether tsDCS-evoked modulations of motoneuron properties are able to persist over several hours. Intracellular recordings from multiple antidromically identified rat motoneurons were performed both before and after the application of tsDCS (0.1 mA for 15 min), at various time points up to 180 min after the offset of anodal or cathodal tsDCS. The examined effects of anodal polarization included decreased rheobase, voltage threshold, the minimum and maximum currents necessary for rhythmic firing, increased rhythmic firing frequencies and the slope of the f-I relationship. The majority of these facilitatory changes to threshold and firing properties were sustained for 30-60 min after polarization. In contrast, the significant effects of cathodal polarization were absent, except the short-lasting decreased ability for motoneurons to induce rhythmic activity. This study provides direct evidence that a single polarization session can alter the electrophysiological properties of motoneurons for at least one hour and provides a basis for the further use of tsDCS techniques under conditions where the sustained modification of motoneuron firing is desired.

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“…As the effects of conditioning stimuli were long-lasting, this often restricted the analysis to one sequence of recordings in the individual rat. Two or three sequences were used only when the effects of the epidural polarizing pulses on peripherally recorded nerve fibers were analyzed, because effects of such pulses are evoked within a radius of Ͻ1 mm (Jankowska et al 2017;Kaczmarek and Jankowska 2018). The subsequently explored regions of the spinal cord were at least 2-3 mm apart, and the results from each of these regions were, therefore, considered as independent.…”

Section: Methodsmentioning

confidence: 99%

“…Activity-independent effects of polarizing current pulses. The mechanisms behind sustained effects of DC on fiber excitability remain to be defined, and only some of the questions concerning these mechanisms have so far been addressed (see Jankowska et al 2016 andJankowska 2018). One of these was whether the facilitation depends exclusively on the fiber polarization or whether it requires a concomitant activation of the fibers to take effect.…”

Section: Effects Of Intermittent Epidurally Applied DC Cathodal Pulsesmentioning

confidence: 99%

Long-term effects of direct current are reproduced by intermittent depolarization of myelinated nerve fibers

Bączyk

Jankowska

2018

Journal of Neurophysiology

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Direct current (DC) potently increases the excitability of myelinated afferent fibers in the dorsal columns, both during DC polarization of these fibers and during a considerable (>1 h) postpolarization period. The aim of the present study was to investigate whether similarly long-lasting changes in the excitability of myelinated nerve fibers in the dorsal columns may be evoked by field potentials following stimulation of peripheral afferents and by subthreshold epidurally applied current pulses. The experiments were performed in deeply anesthetized rats. The effects were monitored by changes in nerve volleys evoked in epidurally stimulated hindlimb afferents and in the synaptic actions of these afferents. Both were found to be facilitated during as well as following stimulation of a skin nerve and during as well as following epidurally applied current pulses of 5- to 10-ms duration. The facilitation occurring ≤2 min after skin nerve stimulation could be linked to both primary afferent depolarization and large dorsal horn field potentials, whereas the subsequent changes (up to 1 h) were attributable to effects of the field potentials. The findings lead to the conclusion that the modulation of spinal activity evoked by DC does not require long-lasting polarization and that relatively short current pulses and intrinsic field potentials may contribute to plasticity in spinal activity. These results suggest the possibility of enhancing the effects of epidural stimulation in human subjects by combining it with polarizing current pulses and peripheral afferent stimulation and not only with continuous DC. NEW & NOTEWORTHY The aim of this study was to define conditions under which a long-term increase is evoked in the excitability of myelinated nerve fibers. The results demonstrate that a potent and long-lasting increase in the excitability of afferent fibers traversing the dorsal columns may be induced by synaptically evoked intrinsic field as well as by epidurally applied intermittent current pulses. They thus provide a new means for the facilitation of the effects of epidural stimulation.

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DC-Evoked Modulation of Excitability of Myelinated Nerve Fibers and Their Terminal Branches; Differences in Sustained Effects of DC

Cited by 16 publications

References 49 publications

Ephaptic interactions between myelinated nerve fibres of rodent peripheral nerves

Ephaptic interactions between myelinated nerve fibres of rodent peripheral nerves

Long‐lasting modifications of motoneuron firing properties by trans‐spinal direct current stimulation in rats

Long-term effects of direct current are reproduced by intermittent depolarization of myelinated nerve fibers

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