Modeling trans-spinal direct current stimulation for the modulation of the lumbar spinal motor pathways

Kuck, Alexander; Stegeman, Dick F.; Asseldonk, Edwin H.F. van

doi:10.1088/1741-2552/aa7960

Cited by 37 publications

(61 citation statements)

References 53 publications

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“…The bottom of the anode (circular shape; 3.2 cm diameter) was placed in the midline of the vertebral column 5 cm above the upper edge of the cathode (Ugawa et al., ), corresponding to the level of the eighth thoracic spinous process (T 8 ). Based on modelling studies, this electrode configuration was chosen as it is likely to induce the greatest electric field magnitude between T 10 and T 12 spinous processes due to electric field being highest between the stimulating electrodes (Kuck et al., ). As such, the site of greatest spinal cord activation is likely to occur between the L 1 –L 5 spinal segments, corresponding to the motoneuron pools of RF and TA (Sayenko et al., ; Sharrad, ).…”

Section: Methodsmentioning

confidence: 99%

“…Based on modelling studies, this electrode configuration was chosen as it is likely to induce the greatest electric field magnitude between T 10 and T 12 spinous processes due to electric field being highest between the stimulating electrodes (Kuck et al, 2017). As such, the site of greatest spinal cord activation is likely to occur between the L 1 -L 5 spinal segments, corresponding to the motoneuron pools of RF and TA (Sayenko et al, 2015;Sharrad, 1964).…”

Section: Electrical Stimulation Of the First Lumbar Spinous Processmentioning

confidence: 99%

“…Stimulation applied closer to these projections will likely result in a higher current density in the lower limb motoneurons when compared to mastoid or thoracic stimulation. Indeed, Kuck, Stegeman, and van Asseldonk () and Fernandes, Salvador, Wenger, de Carvalho, and Miranda () have shown, via modelling techniques, that when the cathode and anode are placed over the lumbar and thoracic spinous processes, respectively, the highest density of electrical field is concentrated around the spinal cord segments associated with lower limb projections. Furthermore, these modelling studies also indicated that electric field magnitude is likely to be higher in the lateral spinal cord white matter where the lateral corticospinal tract is located.…”

Section: Introductionmentioning

confidence: 99%

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Electrical stimulation of human corticospinal axons at the level of the lumbar spinal segments

Škarabot

Ansdell

Brownstein

et al. 2019

Eur J of Neuroscience

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Electrical stimulation over the mastoids or thoracic spinous processes has been used to assess subcortical contribution to corticospinal excitability, but responses are difficult to evoke in the resting lower limbs or are limited to only a few muscle groups. This might be mitigated by delivering the stimuli lower on the spinal column, where the descending tracts contain a greater relative density of motoneurons projecting to lower limb muscles. We investigated activation of the corticospinal axons innervating tibialis anterior (TA) and rectus femoris (RF) by applying a single electrical stimulus over the first lumbar spinous process (LS). LS was paired with transcranial magnetic stimulation (TMS) at interstimulus intervals (ISIs) of −16 (TMS before LS) to 14 ms (LS before TMS). The relationship between muscle contraction strength (10%–100% maximal) and the amplitude of single‐pulse TMS and LS responses was also investigated. Compared to the responses to TMS alone, responses to paired stimulation were significantly occluded in both muscles for ISIs ≥−8 ms (p ≤ 0.035), consistent with collision of descending volleys from TMS with antidromic volleys originating from LS. This suggests that TMS and LS activate some of the same corticospinal axons. Additionally, the amplitude of TMS and LS responses increased with increasing contraction strengths with no change in onset latency, suggesting responses to LS are evoked transsynaptically and have a monosynaptic component. Taken together, these experiments provide evidence that LS is an alternative method that could be used to discern segmental changes in the corticospinal tract when targeting lower limb muscles.

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Section: Methodsmentioning

confidence: 99%

Section: Electrical Stimulation Of the First Lumbar Spinous Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrical stimulation of human corticospinal axons at the level of the lumbar spinal segments

Škarabot

Ansdell

Brownstein

et al. 2019

Eur J of Neuroscience

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“…The field strength and the efficiency of tsDCS in activating the different neuronal elements in the human spinal cord therefore will strongly depend on individual differences in tissue properties and anatomical factors, as well as a range of physical factors related to the stimulation conditions (e.g., electrode size, conductive material, placement of electrodes). Studies on the distribution of the current applied by tsDCS in human participants have also indicated that the field may vary from being insufficient to reach the spinal cord at all to being sufficiently strong to influence neuronal elements in the ventral spinal cord (Bastos et al, 2016;Fernandes, Salvador, Wenger, de Carvalho, & Miranda, 2018;Kuck, Stegeman, & van Asseldonk, 2017). There is clearly a need for improved means of monitoring the distribution and strength of the applied current in individual experiments to obtain more consistent effects and in order F I G U R E 5 Effects of tsDCS on short-latency facilitation of the soleus H-reflex.…”

Section: Variability Of Effectsmentioning

confidence: 99%

Transcutaneous spinal direct current stimulation increases corticospinal transmission and enhances voluntary motor output in humans

et al. 2020

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Optimization of motor performance is of importance in daily life, in relation to recovery following injury as well as for elite sports performance. The present study investigated whether transcutaneous spinal direct current stimulation (tsDCS) may enhance voluntary ballistic activation of ankle muscles and descending activation of spinal motor neurons in able‐bodied adults. Forty‐one adults (21 men; 24.0 ± 3.2 years) participated in the study. The effect of tsDCS on ballistic motor performance and plantar flexor muscle activation was assessed in a double‐blinded sham‐controlled cross‐over experiment. In separate experiments, the underlying changes in excitability of corticospinal and spinal pathways were probed by evaluating soleus (SOL) motor evoked potentials (MEPs) following single‐pulse transcranial magnetic stimulation (TMS) over the primary motor cortex, SOL H‐reflexes elicited by tibial nerve stimulation and TMS‐conditioning of SOL H‐reflexes. Measures were obtained before and after cathodal tsDCS over the thoracic spine (T11‐T12) for 10 min at 2.5 mA. We found that cathodal tsDCS transiently facilitated peak acceleration in the ballistic motor task compared to sham tsDCS. Following tsDCS, SOL MEPs were increased without changes in H‐reflex amplitudes. The short‐latency facilitation of the H‐reflex by subthreshold TMS, which is assumed to be mediated by the fast conducting monosynaptic corticomotoneuronal pathway, was also enhanced by tsDCS. We argue that tsDCS briefly facilitates voluntary motor output by increasing descending drive from corticospinal neurones to spinal plantar flexor motor neurons. tsDCS can thus transiently promote within‐session CNS function and voluntary motor output and holds potential as a technique in the rehabilitation of motor function following central nervous lesions.

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“…provided mechanistic foundation to these empirical findings (29)(30)(31)(32). It is then possible that tsDCS could also influence locomotor learning.…”

Section: Introductionmentioning

confidence: 87%

Transcutaneous spinal direct current stimulation improves locomotor learning in healthy humans

Awosika

Sandrini

Volochayev³

et al. 2019

Brain Stimulation

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Background: Ambulation is an essential aspect of daily living and is often impaired after brain and spinal cord injuries. Despite the implementation of standard neurorehabilitative care, locomotor recovery is often incomplete. Objective: In this randomized, sham-controlled, double-blind, parallel design study, we aimed to determine if anodal transcutaneous spinal direct current stimulation (anodal tsDCS) could improve training effects on locomotion compared to sham (sham tsDCS) in healthy subjects. Methods: 43 participants underwent a single backwards locomotion training (BLT) session on a reverse treadmill with concurrent anodal (n=22) or sham (n=21) tsDCS. The primary outcome measure was speed gain measured 24 hours post-training. We hypothesized that anodal tsDCS+BLT would improve training effects on backward locomotor speed compared to sham tsDCS+BLT. A subset of participants (n=31) returned for two additional training days of either anodal (n=16) or sham (n=15) tsDCS and underwent (n=29) H-reflex testing immediately before, immediately after, and 30 minutes post-training over three consecutive days. Results: A single session of anodal tsDCS+BLT elicited greater speed gain at 24 hours relative to sham tsDCS+BLT (p=0.008, two-sample t-test, adjusted for one interim analysis after the initial 12 subjects). Anodal tsDCS+BLT resulted in higher retention of the acquired skill at day 30 relative to sham tsDCS+BLT (p=0.002) in the absence of significant group differences in online or offline learning over the three training days (p=0.467 and p=0.131). BLT resulted in transient down-regulation of H-reflex amplitude (Hmax/Mmax) in both test groups (p<0.0001). However, the concurrent application of anodal-tsDCS with BLT elicited a longer lasting effect than sham-tsDCS+BLT (p=0.050). Conclusion: TsDCS improved locomotor skill acquisition and retention in healthy subjects and prolonged the physiological exercise-mediated downregulation of excitability of the alpha motoneuron pool. These results suggest that this strategy is worth exploring in neurorehabilitation of locomotor function.

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Modeling trans-spinal direct current stimulation for the modulation of the lumbar spinal motor pathways

Abstract: We provide methods and knowledge for better understanding the effects of tsDCS and serve as a basis for a more targeted and optimized application of tsDCS.

Cited by 37 publications

References 53 publications

Electrical stimulation of human corticospinal axons at the level of the lumbar spinal segments

Electrical stimulation of human corticospinal axons at the level of the lumbar spinal segments

Transcutaneous spinal direct current stimulation increases corticospinal transmission and enhances voluntary motor output in humans

Transcutaneous spinal direct current stimulation improves locomotor learning in healthy humans

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