Effect of flipped venous catheter combined with spinal cord electrical stimulation on functional recovery in patients with sciatic nerve injury.

OBJECTIVE: This study aimed to explore the effect of flipped venous catheters combined with spinal cord electrical stimulation on functional recovery in patients with sciatic nerve injury. PATIENTS AND METHODS: 160 patients with hip dislocation and sciatic nerve injury were divided into conventional release and flipped catheter + electrical stimulation groups according to the treatment methods (n=80). Motor nerve conduction velocity (MCV) and lower limb motor function were compared. Serum neurotrophic factors brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were compared. The frequency of complications and quality of life were also compared. RESULTS: The MCV levels of the common peroneal nerve and tibial nerve in the flipped catheter + electrical stimulation group were greater than the conventional lysis group (p<0.05). After treatment, the lower extremity motor score (LMEs) in the flipped catheter + electrical stimulation group was greater than the conventional lysis group (p<0.05). The serum levels of BDNF and NGF in the flip catheter + electrical stimulation group were higher than the conventional lysis group (p<0.05). The complication rate in the flipped catheter + electrical stimulation group was lower than in the conventional release group (6.25% vs. 16.25%, p<0.05). The quality-of-life score in the flip catheter + electrical stimulation group was greater than the conventional lysis group (p<0.05). CONCLUSIONS: The flipped venous catheter combined with spinal cord electrical stimulation can improve nerve conduction velocity, lower limb motor function, serum BDNF and NGF levels, reduce complications, and help improve the quality of life of sufferers with sciatic nerve injury. Chictr.org.cn ID: ChiCTR2400080984.

Electrical stimulation of the lower eyelid orbicularis oculi muscle improves periocular dark circles.

BACKGROUND: We developed and tested the safety and efficacy of a cosmetic device to improve dark circles using electrical muscle stimulation of the orbicularis oculi muscle. METHODS: Overall, 18 participants (36 eyes) were studied. The following five items were evaluated before and after the intervention:(1) the Clinical Dark Circle Score using clinical findings and photographs, (2) transcutaneous oxygen partial pressure (TcPO2) on the lower eyelid, (3) thermography, (4) two-dimensional laser blood flowmetry, and (5) spectrophotometry. RESULTS: The mean score at baseline was 2.0 ± 0.90 (mean ± standard deviation), and that at the end of the study was 1.2 ± 1.0 (Wilcoxon signed-rank sum test, p < 0.0001), indicating a significant reduction. The spectrophotometer showed a significant decrease in a* and L* values before and after use (Wilcoxon signed-rank sum test, p < 0.0001). There was also a weak negative correlation between the change in score and the change in blood flow and TcPO2 measured using a laser perfusion device (Spearman's rank correlation coefficient, r = -0.32 and -0.39, respectively). Stratified analysis of the baseline score showed a strong negative correlation between the change in score and the change in spectrophotometric a* in the subjects/group with mild periocular dark circles (Spearman's rank correlation coefficient, r = -0.46). Contrastingly, no correlation was observed for any of the measurements in the subjects/group with severe periocular dark circles. After 1 month, no device-related ophthalmic adverse events were observed in any of the participants. CONCLUSION: Electrical muscle stimulation could improve periocular dark circles, especially in the subjects/group with mild periocular dark circles, and was safe.

Near-InfraRed Spectroscopy Provides a Reproducible Estimate of Muscle Aerobic Capacity, but Not Whole-Body Aerobic Power.

Near-infrared spectroscopy (NIRS) during repeated limb occlusions is a noninvasive tool for assessing muscle oxidative capacity. However, the method's reliability and validity remain under investigation. This study aimed to determine the reliability of the NIRS-derived mitochondrial power of the musculus vastus lateralis and its correlation with whole-body (cycling) aerobic power (V̇O2 peak). Eleven healthy active men (28 ± 10 y) twice (2 days apart) underwent repeated arterial occlusions to induce changes in muscle oxygen delivery after 15 s of electrical muscle stimulation. The muscle oxygen consumption (mV̇O2) recovery time and rate (k) constants were calculated from the NIRS O2Hb signal. We assessed the reliability (coefficient of variation and intraclass coefficient of correlation [ICC]) and equivalency (t-test) between visits. The results showed high reproducibility for the mV̇O2 recovery time constant (ICC = 0.859) and moderate reproducibility for the k value (ICC = 0.674), with no significant differences between visits (p > 0.05). NIRS-derived k did not correlate with the V̇O2 peak relative to body mass (r = 0.441, p = 0.17) or the absolute V̇O2 peak (r = 0.366, p = 0.26). In conclusion, NIRS provides a reproducible estimate of muscle mitochondrial power, which, however, was not correlated with whole-body aerobic capacity in the current study, suggesting that even if somewhat overlapping, not the same set of factors underpin these distinct indices of aerobic capacity at the different (peripheral and whole-body systemic) levels.

In a porcine model of implantable pacemakers for pediatric unilateral diaphragm paralysis, the phrenic nerve is the best target.

BACKGROUND: A frequent complication of Fontan operations is unilateral diaphragmatic paresis, which leads to hemodynamic deterioration of the Fontan circulation. A potential new therapeutic option is the unilateral diaphragmatic pacemaker. In this study, we investigated the most effective stimulation location for a potential fully implantable system in a porcine model. METHODS: Five pigs (20.8 ± 0.95 kg) underwent implantation of a customized cuff electrode placed around the right phrenic nerve. A bipolar myocardial pacing electrode was sutured adjacent to the motor point and peripherally at the costophrenic angle (peripheral diaphragmatic muscle). The electrodes were stimulated 30 times per minute with a pulse duration of 200 µs and a stimulation time of 300 ms. Current intensity was the only variable changed during the experiment. RESULTS: Effective stimulation occurred at 0.26 ± 0.024 mA at the phrenic nerve and 7 ± 1.22 mA at the motor point, a significant difference in amperage (p = 0.005). Even with a maximum stimulation of 10 mA at the peripheral diaphragm muscle, however, no effective stimulation was observed. CONCLUSION: The phrenic nerve seems to be the best location for direct stimulation by a unilateral thoracic diaphragm pacemaker in terms of the required amperage level in a porcine model.

Recognition of Human Lower Limb Motion and Muscle Fatigue Status Using a Wearable FES-sEMG System.

Functional electrical stimulation (FES) devices are widely employed for clinical treatment, rehabilitation, and sports training. However, existing FES devices are inadequate in terms of wearability and cannot recognize a user's intention to move or muscle fatigue. These issues impede the user's ability to incorporate FES devices into their daily life. In response to these issues, this paper introduces a novel wearable FES system based on customized textile electrodes. The system is driven by surface electromyography (sEMG) movement intention. A parallel structured deep learning model based on a wearable FES device is used, which enables the identification of both the type of motion and muscle fatigue status without being affected by electrical stimulation. Five subjects took part in an experiment to test the proposed system, and the results showed that our method achieved a high level of accuracy for lower limb motion recognition and muscle fatigue status detection. The preliminary results presented here prove the effectiveness of the novel wearable FES system in terms of recognizing lower limb motions and muscle fatigue status.

Cellular mechanisms underlying carry-over effects after magnetic stimulation.

Magnetic fields are widely used for neuromodulation in clinical settings. The intended effect of magnetic stimulation is that neural activity resumes its pre-stimulation state right after stimulation. Many theoretical and experimental works have focused on the cellular and molecular basis of the acute neural response to magnetic field. However, effects of magnetic stimulation can still last after the termination of the magnetic stimulation (named "carry-over effects"), which could generate profound effects to the outcome of the stimulation. However, the cellular and molecular mechanisms of carry-over effects are largely unknown, which renders the neural modulation practice using magnetic stimulation unpredictable. Here, we investigated carry-over effects at the cellular level, using the combination of micro-magnetic stimulation (µMS), electrophysiology, and computation modeling. We found that high frequency magnetic stimulation could lead to immediate neural inhibition in ganglion neurons from Aplysia californica, as well as persistent, carry-over inhibition after withdrawing the magnetic stimulus. Carry-over effects were found in the neurons that fired action potentials under a variety of conditions. The carry-over effects were also observed in the neurons when the magnetic field was applied across the ganglion sheath. The state of the neuron, specifically synaptic input and membrane potential fluctuation, plays a significant role in generating the carry-over effects after magnetic stimulation. To elucidate the cellular mechanisms of such carry-over effects under magnetic stimulation, we simulated a single neuron under magnetic stimulation with multi-compartment modeling. The model successfully replicated the carry-over effects in the neuron, and revealed that the carry-over effect was due to the dysfunction of the ion channel dynamics that were responsible for the initiation and sustaining of membrane excitability. A virtual voltage-clamp experiment revealed a compromised Na conductance and enhanced K conductance post magnetic stimulation, rendering the neurons incapable of generating action potentials and, therefore, leading to the carry over effects. Finally, both simulation and experimental results demonstrated that the carry-over effects could be controlled by disturbing the membrane potential during the post-stimulus inhibition period. Delineating the cellular and ion channel mechanisms underlying carry-over effects could provide insights to the clinical outcomes in brain stimulation using TMS and other modalities. This research incentivizes the development of novel neural engineering or pharmacological approaches to better control the carry-over effects for optimized clinical outcomes.

Ischemic preconditioning increases spinal excitability and voluntary activation during maximal plantar flexion contractions in men.

The enigmatic benefits of acute limb ischemic preconditioning (IP) in enhancing muscle force and exercise performance have intrigued researchers. This study sought to unravel the underlying mechanisms, focusing on increased neural drive and the role of spinal excitability while excluding peripheral factors. Soleus Hoffmann (H)-reflex /M-wave recruitment curves and unpotentiated supramaximal responses were recorded before and after IP or a low-pressure control intervention. Subsequently, the twitch interpolation technique was applied during maximal voluntary contractions to assess conventional parameters of neural output. Following IP, there was an increase in both maximum normalized force and voluntary activation (VA) for the plantar flexor group, with negligible peripheral alterations. Greater benefits were observed in participants with lower VA levels. Despite greater H-reflex gains, soleus volitional (V)-wave and sEMG amplitudes remained unchanged. In conclusion, IP improves muscle force via enhanced neural drive to the muscles. This effect appears associated, at least in part, to reduced presynaptic inhibition and/or increased motoneuron excitability. Furthermore, the magnitude of the benefit is inversely proportional to the skeletal muscle's functional reserve, making it particularly noticeable in under-recruited muscles. These findings have implications for the strategic application of the IP procedure across diverse populations.

Effects of upper limbs' neuromuscular electrical stimulation (NMES) superimposed to voluntary contraction added to a protocol of intradialytic leg cycle ergometer exercise, in muscle strength, functional capacity and quality of life of adult patients with CKD: a randomized clinical trial protocol.

OBJECTIVE: To investigate the effects of unilateral upper limbs' (ULM) neuromuscular electrical stimulation (NMES) superimposed on a voluntary contraction added to a protocol of intradialytic leg cycle ergometer exercise on muscle strength, functional capacity and quality of life of adult patients with chronic kidney disease (CKD). METHODS: This randomized controlled clinical trial will be carried out at a Brazilian University Hospital. The patients will be evaluated and randomly allocated to an intervention group (i.e., unilateral NMES on the upper limb without hemodialysis fistula for 20 min and leg cycle ergometer for 30 min) or a control group (i.e., unilateral NMES-Sham on the upper limb without hemodialysis fistula for 20 min and leg cycle ergometer for 30 min). The patients will be treated for 8 weeks, with three weekly treatment sessions totaling 24 sessions. MEASUREMENTS: ULM muscle strength, functional capacity, quality of life and also the feasibility, safety and patient adherence to the exercise protocol. All physical measurements will be collected by trained researchers before treatment (week 0) and at the end of treatment (week 9), always in the second hemodialysis session of the week. It will be used in an intention-to-treat analysis. RESULTS/CONCLUSIONS: The outcomes of this clinical trial protocol may help to know the possible benefits of unilateral ULM' NMES superimposed on a voluntary contraction added to a protocol of leg cycle ergometer for patients with CKD and to aid clinical decisions about future implementation or not of this technique (NMES) in intradialytic physical training programs.

Reduced Graphene Oxide Fibers Combined with Electrical Stimulation Promote Peripheral Nerve Regeneration.

Background: The treatment of long-gap peripheral nerve injury (PNI) is still a substantial clinical problem. Graphene-based scaffolds possess extracellular matrix (ECM) characteristic and can conduct electrical signals, therefore have been investigated for repairing PNI. Combined with electrical stimulation (ES), a well performance should be expected. We aimed to determine the effects of reduced graphene oxide fibers (rGOFs) combined with ES on PNI repair in vivo. Methods: rGOFs were prepared by one-step dimensionally confined hydrothermal strategy (DCH). Surface characteristics, chemical compositions, electrical and mechanical properties of the samples were characterized. The biocompatibility of the rGOFs were systematically explored both in vitro and in vivo. Total of 54 Sprague-Dawley (SD) rats were randomized into 6 experimental groups: a silicone conduit (S), S+ES, S+rGOFs-filled conduit (SGC), SGC+ES, nerve autograft, and sham groups for a 10-mm sciatic defect. Functional and histological recovery of the regenerated sciatic nerve at 12 weeks after surgery in each group of SD rats were evaluated. Results: rGOFs exhibited aligned micro- and nano-channels with excellent mechanical and electrical properties. They are biocompatible in vitro and in vivo. All 6 groups exhibited PNI repair outcomes in view of neurological and morphological recovery. The SGC+ES group achieved similar therapeutic effects as nerve autograft group (P > 0.05), significantly outperformed other treatment groups. Immunohistochemical analysis showed that the expression of proteins related to axonal regeneration and angiogenesis were relatively higher in the SGC+ES. Conclusion: The rGOFs had good biocompatibility combined with excellent electrical and mechanical properties. Combined with ES, the rGOFs provided superior motor nerve recovery for a 10-mm nerve gap in a murine acute transection injury model, indicating its excellent repairing ability. That the similar therapeutic effects as autologous nerve transplantation make us believe this method is a promising way to treat peripheral nerve defects, which is expected to guide clinical practice in the future.

[Advances in the use of neuromuscular electrical stimulation in the prevention of venous thromboembolism].

Pharmacologic prophylaxis is the most commonly used prophylaxis for venous thromboembolism (VTE), but the pharmacologic prophylaxis is limited in patients at high risk of bleeding. Mechanical prophylaxis alone or in combination is an important method of VTE prophylaxis in patients at high risk of bleeding, but the current mainstream mechanical prophylaxis, which includes graded compression stockings, intermittent inflatable compression pumps and plantar venous compression pumps, has some limitations, leading to discomfort for patients wearing them due to the large contact area, and even affecting ability to perform daily activities. Many clinical studies have found that NMES combined with pharmacological prophylaxis has better efficacy and safety than pharmacological prophylaxis alone in preventing VTE in medical and surgical patients, and the preventive effect of NMES alone is not inferior to other mechanical prophylaxis. Besides, it also has the advantages of ease of wear and patient compliance. Currently, clinicians have limited experience and knowledge of NMES. We aimed to present the rationale, progress in clinical research and future perspective of NMES in VTE prophylaxis.

Belt electrode tetanus muscle stimulation reduces denervation-induced atrophy of rat multiple skeletal muscle groups.

Belt electrode-skeletal muscle electrical stimulation (B-SES) involves the use of belt-shaped electrodes to contract multiple muscle groups simultaneously. Twitch contractions have been demonstrated to protect against denervation-induced muscle atrophy in rats, possibly through mitochondrial biosynthesis. This study examined whether inducing tetanus contractions with B-SES suppresses muscle atrophy and identified the underlying molecular mechanisms. We evaluated the effects of acute (60 Hz, 5 min) and chronic (60 Hz, 5 min, every alternate day for one week) B-SES on the tibialis anterior (TA) and gastrocnemius (GAS) muscles in Sprague-Dawley rats using belt electrodes attached to both ankle joints. After acute stimulation, a significant decrease in the glycogen content was observed in the left and right TA and GAS, suggesting that B-SES causes simultaneous contractions in multiple muscle groups. B-SES enhanced p70S6K phosphorylation, an indicator of the mechanistic target of rapamycin complex 1 activity. During chronic stimulations, rats were divided into control (CONT), denervation-induced atrophy (DEN), and DEN + electrically stimulated with B-SES (DEN + ES) groups. After seven days of treatment, the wet weight (n = 8-11 for each group) and muscle fiber cross-sectional area (CSA, n = 6 for each group) of the TA and GAS muscles were reduced in the DEN and DEN + ES groups compared with that in the CON group. The DEN + ES group showed significantly higher muscle weight and CSA than those in the DEN group. Although RNA-seq and pathway analysis suggested that mitochondrial biogenesis is a critical event in this phenomenon, mitochondrial content showed no difference. In contrast, ribosomal RNA 28S and 18S (n = 6) levels in the DEN + ES group were higher than those in the DEN group, even though RNA-seq showed that the ribosome biogenesis pathway was reduced by electrical stimulation. The mRNA levels of the muscle proteolytic molecules atrogin-1 and MuRF1 were significantly higher in DEN than those in CONT. However, they were more suppressed in DEN + ES than those in DEN. In conclusion, tetanic electrical stimulation of both ankles using belt electrodes effectively reduced denervation-induced atrophy in multiple muscle groups. Furthermore, ribosomal biosynthesis plays a vital role in this phenomenon.

Optimization of pacing parameters to entrain slow wave activity in the pig jejunum.

Pacing has been proposed as a therapy to restore function in motility disorders associated with electrical dysrhythmias. The spatial response of bioelectrical activity in the small intestine to pacing is poorly understood due to a lack of high-resolution investigations. This study systematically varied pacing parameters to determine the optimal settings for the spatial entrainment of slow wave activity in the jejunum. An electrode array was developed to allow simultaneous pacing and high-resolution mapping of the small intestine. Pacing parameters including pulse-width (50, 100 ms), pulse-amplitude (2, 4, 8 mA) and pacing electrode orientation (antegrade, retrograde, circumferential) were systematically varied and applied to the jejunum (n = 15 pigs). Pulse-amplitudes of 4 mA (p = 0.012) and 8 mA (p = 0.002) were more effective than 2 mA in achieving spatial entrainment while pulse-widths of 50 ms and 100 ms had comparable effects (p = 0.125). A pulse-width of 100 ms and a pulse-amplitude of 4 mA were determined to be most effective for slow wave entrainment when paced in the antegrade or circumferential direction with a success rate of greater than 75%. These settings can be applied in chronic studies to evaluate the long-term efficacy of pacing, a critical aspect in determining its therapeutic potential.

Use of high-frequency electrical stimulation in gastrocutaneous fistula closure: a case report.

BACKGROUND: Gastrocutaneous fistula is a rare complication following Roux-en-Y gastric bypass, a commonly performed bariatric surgery. While most ECFs respond to conservative management, some do not close despite adequate nutritional support, infection source control, and drainage management. As such, the chronicity of these difficult-to-treat wounds can be physically and economically costly to patients. CASE REPORT: A 53-year-old female with a history of Roux-en-Y gastric bypass developed a gastrocutaneous fistula secondary to a perforated gastrojejunal ulcer, requiring immediate surgical intervention. After being discharged from the hospital, 37 days of conservative management and NPWT did not reduce the size of the fistula tract. To help control the patient's chronic abdominal pain and increase the rate of wound healing, the patient underwent treatment with HFES (20 kHz) delivered using a handheld transcutaneous electrical nerve stimulator. This electrotherapy was found to reduce the majority of the patient's pain within the first treatment session. The patient's fistula also began to decrease in size within 1 week of initiating treatment. CONCLUSION: This case report details the successful closure of a gastrocutaneous fistula after administration of HFES 3 times a week over the course of 25 days. The mechanism of action of HFES and its role in the wound healing process are also discussed.

Hypothalamic Paraventricular Stimulation Inhibits Nociceptive Wide Dynamic Range Trigeminocervical Complex Cells via Oxytocinergic Transmission.

Oxytocinergic transmission blocks nociception at the peripheral, spinal, and supraspinal levels through the oxytocin receptor (OTR). Indeed, a neuronal pathway from the hypothalamic paraventricular nucleus (PVN) to the spinal cord and trigeminal nucleus caudalis (Sp5c) has been described. Hence, although the trigeminocervical complex (TCC), an anatomical area spanning the Sp5c, C1, and C2 regions, plays a role in some pain disorders associated with craniofacial structures (e.g., migraine), the role of oxytocinergic transmission in modulating nociception at this level has been poorly explored. Hence, in vivo electrophysiological recordings of TCC wide dynamic range (WDR) cells sensitive to stimulation of the periorbital or meningeal region were performed in male Wistar rats. PVN electrical stimulation diminished the neuronal firing evoked by periorbital or meningeal electrical stimulation; this inhibition was reversed by OTR antagonists administered locally. Accordingly, neuronal projections (using Fluoro-Ruby) from the PVN to the WDR cells filled with Neurobiotin were observed. Moreover, colocalization between OTR and calcitonin gene-related peptide (CGRP) or OTR and GABA was found near Neurobiotin-filled WDR cells. Retrograde neuronal tracers deposited at the meningeal (True-Blue, TB) and infraorbital nerves (Fluoro-Gold, FG) showed that at the trigeminal ganglion (TG), some cells were immunopositive to both fluorophores, suggesting that some TG cells send projections via the V1 and V2 trigeminal branches. Together, these data may imply that endogenous oxytocinergic transmission inhibits the nociceptive activity of second-order neurons via OTR activation in CGRPergic (primary afferent fibers) and GABAergic cells.

Skeletal muscle fiber type and TMS-induced muscle relaxation in unfatigued and fatigued knee-extensor muscles.

The force drop after transcranial magnetic stimulation (TMS) delivered to the motor cortex during voluntary muscle contractions could inform about muscle relaxation properties. Because of the physiological relation between skeletal muscle fiber-type distribution and size and muscle relaxation, TMS could be a noninvasive index of muscle relaxation in humans. By combining a noninvasive technique to record muscle relaxation in vivo (TMS) with the gold standard technique for muscle tissue sampling (muscle biopsy), we investigated the relation between TMS-induced muscle relaxation in unfatigued and fatigued states, and muscle fiber-type distribution and size. Sixteen participants (7F/9M) volunteered to participate. Maximal knee-extensor voluntary isometric contractions were performed with TMS before and after a 2-min sustained maximal voluntary isometric contraction. Vastus lateralis muscle tissue was obtained separately from the participants' dominant limb. Fiber type I distribution and relative cross-sectional area of fiber type I correlated with TMS-induced muscle relaxation at baseline (r = 0.67, adjusted P = 0.01; r = 0.74, adjusted P = 0.004, respectively) and normalized TMS-induced muscle relaxation as a percentage of baseline (r = 0.50, adjusted P = 0.049; r = 0.56, adjusted P = 0.031, respectively). The variance in the normalized peak relaxation rate at baseline (59.8%, P < 0.001) and in the fatigue resistance (23.0%, P = 0.035) were explained by the relative cross-sectional area of fiber type I to total fiber area. Fiber type I proportional area influences TMS-induced muscle relaxation, suggesting TMS as an alternative method to noninvasively inform about skeletal muscle relaxation properties.NEW & NOTEWORTHY Transcranial magnetic stimulation (TMS)-induced muscle relaxation reflects intrinsic muscle contractile properties by interrupting the drive from the central nervous system during voluntary muscle contractions. We showed that fiber type I proportional area influences the TMS-induced muscle relaxation, suggesting that TMS could be used for the noninvasive estimation of muscle relaxation in unfatigued and fatigued human muscles when the feasibility of more direct method to study relaxation properties (i.e., muscle biopsy) is restricted.

Electrical stimulation of chicken embryo development supports the Inside story scenario of human development and evolution.

Animal evolution is driven by random mutations at the genome level. However, it has long been suggested that there exist physical constraints which limit the set of possible outcomes. In craniate evolution, it has been observed that head features, notably in the genus homo, can be ordered in a morphological diagram such that, as the brain expands, the head rocks more forward, face features become less prognathous and the mouth tends to recede. One school of paleontologists suggests that this trend is wired somewhere structurally inside the anatomy, and that random modifications of genes push up or down animal forms along a pre-determined path. No actual experiment has been able to settle the dispute. I present here an experiment of electric stimulation of the head in the chicken embryo which is able to enhance the magnitude of tension forces during development. This experimental intervention causes a correlated brain shrinkage and rotatory movement of the head, congruent with tissue texture, which proves that head dilation and flexure are intimately linked. Numerical modelling explains why the brain curls when it dilates. This gives support to the idea that there exists, in the texture of the vertebrate embryo, a latent dynamic pattern for the observed paleontological trends in craniates towards homo, a concept known as Inside story.

A biophysically constrained brain connectivity model based on stimulation-evoked potentials.

BACKGROUND: Single-pulse electrical stimulation (SPES) is an established technique used to map functional effective connectivity networks in treatment-refractory epilepsy patients undergoing intracranial-electroencephalography monitoring. While the connectivity path between stimulation and recording sites has been explored through the integration of structural connectivity, there are substantial gaps, such that new modeling approaches may advance our understanding of connectivity derived from SPES studies. NEW METHOD: Using intracranial electrophysiology data recorded from a single patient undergoing stereo-electroencephalography (sEEG) evaluation, we employ an automated detection method to identify early response components, C1, from pulse-evoked potentials (PEPs) induced by SPES. C1 components were utilized for a novel topology optimization method, modeling 3D electrical conductivity to infer neural pathways from stimulation sites. Additionally, PEP features were compared with tractography metrics, and model results were analyzed with respect to anatomical features. RESULTS: The proposed optimization model resolved conductivity paths with low error. Specific electrode contacts displaying high error correlated with anatomical complexities. The C1 component strongly correlated with additional PEP features and displayed stable, weak correlations with tractography measures. COMPARISON WITH EXISTING METHOD: Existing methods for estimating neural signal pathways are imaging-based and thus rely on anatomical inferences. CONCLUSIONS: These results demonstrate that informing topology optimization methods with human intracranial SPES data is a feasible method for generating 3D conductivity maps linking electrical pathways with functional neural ensembles. PEP-estimated effective connectivity is correlated with but distinguished from structural connectivity. Modeled conductivity resolves connectivity pathways in the absence of anatomical priors.

Dynamics of neuronal firing modulated by high-frequency electrical pulse stimulations at axons in rat hippocampus.

Objective. The development of electrical pulse stimulations in brain, including deep brain stimulation, is promising for treating various brain diseases. However, the mechanisms of brain stimulations are not yet fully understood. Previous studies have shown that the commonly used high-frequency stimulation (HFS) can increase the firing of neurons and modulate the pattern of neuronal firing. Because the generation of neuronal firing in brain is a nonlinear process, investigating the characteristics of nonlinear dynamics induced by HFS could be helpful to reveal more mechanisms of brain stimulations. The aim of present study is to investigate the fractal properties in the neuronal firing generated by HFS.Approach. HFS pulse sequences with a constant frequency 100 Hz were applied in the afferent fiber tracts of rat hippocampal CA1 region. Unit spikes of both the pyramidal cells and the interneurons in the downstream area of stimulations were recorded. Two fractal indexes-the Fano factor and Hurst exponent were calculated to evaluate the changes of long-range temporal correlations (LRTCs), a typical characteristic of fractal process, in spike sequences of neuronal firing.Mainresults. Neuronal firing at both baseline and during HFS exhibited LRTCs over multiple time scales. In addition, the LRTCs significantly increased during HFS, which was confirmed by simulation data of both randomly shuffled sequences and surrogate sequences.Conclusion. The purely periodic stimulation of HFS pulses, a non-fractal process without LRTCs, can increase rather than decrease the LRTCs in neuronal firing.Significance. The finding provides new nonlinear mechanisms of brain stimulation and suggests that LRTCs could be a new biomarker to evaluate the nonlinear effects of HFS.

Effects of galvanic vestibular stimulation on postural righting reactions in hemiplegia.

Patients with post-stroke hemiplegia often exhibit reduced ability to maintain sitting balance, a crucial factor for predicting prognosis. Galvanic vestibular stimulation (GVS) influences postural control by stimulating vestibular organ. Although several studies have focused on GVS in static postures, no studies have demonstrated the influence of GVS on righting reactions. Therefore, we aimed to investigate the effects of GVS on postural righting reactions in seated patients with stroke-induced hemiplegia. Using a vertical board (VB), righting reactions were induced by tilting the VB at 10° after patients sat for 1 min. Patients adjusted their bodies until feeling vertical upon prompt. Twenty-two left hemiplegic patients with cerebrovascular disease participated, divided into two groups undergoing right cathode GVS (RC-GVS) followed by left cathode GVS or vice versa, preceded by sham stimulation. Centre of pressure and the joint angle were measured. During the postural righting reactions towards the paralysed side, RC-GVS enhanced the righting reactions and moved the mean position on the x-axis (COPx) to the right and the mean position on the y-axis (COPy) to the front. During the postural righting reaction towards the right side, RC-GVS induced resistance against the righting reaction, COPx was deflected to the right, COPy was deflected backward, and the angle of the neck tilt increased. The findings revealed that GVS with anodal stimulation on the paralysed side could promote righting reactions in patients with post-stroke hemiplegia. SIGNIFICANCE STATEMENT: The study findings suggest that using the contralesional placement of the anode promotes righting reactions, and galvanic vestibular stimulation can induce joint movements in the neck and trunk by polarising it to act as resistance against righting reactions.

Comparison of the activation level in the sensorimotor cortex between motor point and proximal nerve bundle electrical stimulation.

Objective.Neuromuscular electrical stimulation (NMES) is widely used for motor function rehabilitation in stroke survivors. Compared with the conventional motor point (MP) stimulation, the stimulation at the proximal segment of the peripheral nerve (PN) bundles has been demonstrated to have multiple advantages. However, it is not known yet whether the PN stimulation can increase the cortical activation level, which is crucial for motor function rehabilitation.Approach.The current stimuli were delivered transcutaneously at the muscle belly of the finger flexors and the proximal segment of the median and ulnar nerves, respectively for the MP and PN stimulation. The stimulation intensity was determined to elicit the same contraction levels between the two stimulation methods in 18 healthy individuals and a stroke patient. The functional near-infrared spectroscopy and the electromyogram were recorded to compare the activation pattern of the sensorimotor regions and the target muscles.Main Results.For the healthy subjects, the PN stimulation induced significantly increased concentration of the oxygenated hemoglobin in the contralateral sensorimotor areas, and enhanced the functional connectivity between brain regions compared with the MP stimulation. Meanwhile, the compound action potentials had a smaller amplitude and the H-reflex became stronger under the PN stimulation, indicating that more sensory axons were activated in the PN stimulation. For the stroke patient, the PN stimulation can elicit finger forces and induce activation of both the contralateral and ipsilateral motor cortex.Conclusions. Compared with the MP stimulation, the PN stimulation can induce more cortical activation in the contralateral sensorimotor areas possibly via involving more activities in the central pathway.Significance.This study demonstrated the potential of the PN stimulation to facilitate functional recovery via increasing the cortical activation level, which may help to improve the outcome of the NMES-based rehabilitation for motor function recovery after stroke.