Transcutaneous spinal direct current stimulation of the lumbar and sacral spinal cord: a modelling study

Fernandes, Sofia R.; Salvador, Ricardo; Wenger, Cornelia; Carvalho, Mamede de; Miranda, Pedro C.

doi:10.1088/1741-2552/aaac38

Cited by 33 publications

(71 citation statements)

References 51 publications

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“…Whilst the present data provide evidence that LS and TMS activate similar axons, that is, the pyramidal cells in the corticospinal tract, there remains the possibility that other descending tracts might also be excited and hence be contributing to the observed effects (Ugawa et al., ). Of particular consideration would be those tracts located in the lateral white matter, such as rubrospinal and reticulospinal tracts (Nathan & Smith, ; Nathan et al., ), as modelling studies indicate that electric field magnitude, due to LS, is likely higher at the lateral aspects of the spinal cord where these tracts are located (Fernandes et al., ). Any potential effects from the rubrospinal tract can be discounted as this tract does not project below the cervical region in humans (Nathan & Smith, ).…”

Section: Discussionmentioning

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: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…Over the last 5 years, we have developed a tetrahedral-based human trunk model and studied the current density and EF distribution in the spinal cord for tsDCS and tsMS. We have also introduced anisotropic properties for the spinal white matter and muscle tissues [21,22]. This chapter provides a description of the model design steps and simulation methodology.…”

mentioning

confidence: 99%

Modelling Studies of Non-invasive Electric and Magnetic Stimulation of the Spinal Cord

Fernandes

Salvador²,

Carvalho

et al. 2020

Brain and Human Body Modeling 2020

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Relevance of Modelling Studies in Non-invasive Spinal Stimulation The spinal cord (SC) is a complex set of neural pathways and nuclei where essential reflex responses are generated and where transmission of sensory information and motor instructions takes place between peripheral organs and brain centres. Spinal dysfunctions due to various conditions, such as spinal cord injury (SCI), amyotrophic lateral sclerosis (ALS) and stroke, lead to a decrease in motor performance and sensory perception, causing spasticity, pain and muscular weakness [1]. Electric currents have been applied in the spinal cord for the treatment of chronic pain, resulting, in particular, from spinal cord lesion due to trauma or inflammatory diseases. However, the procedure usually involves surgical introduction of electrodes in the epidural space, which is frequently associated with higher risk of infections and medical costs for the patient [2]. Non-invasive electric and magnetic

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Transcutaneous spinal direct current stimulation of the lumbar and sacral spinal cord: a modelling study

Abstract: Computational modelling studies can provide detailed information regarding the electric field in the spinal cord during tsDCS. They are important to guide the design of clinical tsDCS protocols that optimize stimulation of application-specific spinal targets.

Cited by 33 publications

References 51 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

Modelling Studies of Non-invasive Electric and Magnetic Stimulation of the Spinal Cord

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