Stimulation Frequency Research Articles

A single-center retrospective chart review of percutaneous PNS for treatment of chronic shoulder pain

ObjectiveThe present IRB-approved retrospective chart review describes the use of a 60-day PNS treatment for shoulder pain at a single center in 60 total consecutive patients. BackgroundChronic shoulder pain affects an increasing number of patients per year and is especially prevalent in elderly populations. Percutaneous peripheral nerve stimulation (PNS) treatment targeting the nerves of the shoulder has been shown to reduce pain in prospective clinical studies and in analysis of real-world data. MethodsData were extracted from the electronic medical records of patients who had previously undergone percutaneous PNS treatment for chronic shoulder pain. Demographic data and treatment characteristics were summarized alongside treatment outcomes. ResultsOverall, 84 % (49/58) of patients reported substantial (≥50 %) pain relief at the end-of-treatment. The records for 2 patients did not include patient-reported percent pain relief. The average indwelling period for leads (i.e., treatment period) was 57 days. Findings on treatment effectiveness were consistent when the patient population was stratified by cause of pain, duration living with pain, and presence of pain-modifying comorbidities. Stimulation paradigms were identified and categorized by the nerve target and stimulation frequency (e.g., motor stimulation, sensory stimulation, or bimodal stimulation). ConclusionsThese results indicate percutaneous PNS is an effective treatment for patients with various shoulder pain histories, and while all stimulation paradigms were effective at reducing pain, patients who received bimodal PNS reported the greatest pain relief. Key limitations of the study included heterogeneous shoulder pain etiologies among patients and sparse availability of long-term follow-up data. These data support existing real-world and prospective clinical evidence on the efficacy of 60-day PNS treatment at treating chronic pain and provide valuable insights into its use in clinical practice.

Empathy incites a stable prosocial decision bias.

Empathy toward suffering individuals serves as potent driver for prosocial behavior. However, it remains unclear whether prosociality induced by empathy for another person's pain persists once that person's suffering diminishes. To test this, participants underwent functional magnetic resonance imaging while performing a binary social decision task that involved allocation of points to themselves and another person. In block one, participants completed the task after witnessing frequent painful stimulation of the other person, and in block two, after observing low frequency of painful stimulation. Drift-diffusion modeling revealed an increased initial bias toward making prosocial decisions in the first block compared with baseline that persisted in the second block. These results were replicated in an independent behavioral study. An additional control study showed that this effect may be specific to empathy as stability was not evident when prosocial decisions were driven by a social norm such as reciprocity. Increased neural activation in dorsomedial prefrontal cortex was linked to empathic concern after witnessing frequent pain and to a general prosocial decision bias after witnessing rare pain. Altogether, our findings show that empathy for pain elicits a stable inclination toward making prosocial decisions even as their suffering diminishes.

Differential Responses to Low- and High-Frequency Subthalamic Nucleus Deep Brain Stimulation on Sensor-Measured Components of Bradykinesia in Parkinson's Disease.

The current approach to assessing bradykinesia in Parkinson's Disease relies on the Unified Parkinson's Disease Rating Scale (UPDRS), which is a numeric scale. Inertial sensors offer the ability to probe subcomponents of bradykinesia: motor speed, amplitude, and rhythm. Thus, we sought to investigate the differential effects of high-frequency compared to low-frequency subthalamic nucleus (STN) deep brain stimulation (DBS) on these quantified facets of bradykinesia. We recruited advanced Parkinson's Disease subjects with a chronic bilateral subthalamic nucleus (STN) DBS implantation to a single-blind stimulation trial where each combination of medication state (OFF/ON), electrode contacts, and stimulation frequency (60 Hz/180 Hz) was assessed. The Kinesia One sensor system was used to measure upper limb bradykinesia. For each stimulation trial, subjects performed extremity motor tasks. Sensor data were recorded continuously. We identified STN DBS parameters that were associated with improved upper extremity bradykinesia symptoms using a mixed linear regression model. We recruited 22 subjects (6 females) for this study. The 180 Hz STN DBS (compared to the 60 Hz STN DBS) and dopaminergic medications improved all subcomponents of upper extremity bradykinesia (motor speed, amplitude, and rhythm). For the motor rhythm subcomponent of bradykinesia, ventral contacts yielded improved symptom improvement compared to dorsal contacts. The differential impact of high- and low-frequency STN DBS on the symptoms of bradykinesia may advise programming for these patients but warrants further investigation. Wearable sensors represent a valuable addition to the armamentarium that furthers our ability to conduct objective, quantitative clinical assessments.

Functional consequences of changes in the distribution of Ca2+ extrusion pathways between t-tubular and surface membranes in a model of human ventricular cardiomyocyte

The sarcolemmal Ca2+ efflux pathways, Na+-Ca2+-exchanger (NCX) and Ca2+-ATPase (PMCA), play a crucial role in the regulation of intracellular Ca2+ load and Ca2+ transient in cardiomyocytes. The distribution of these pathways between the t-tubular and surface membrane of ventricular cardiomyocytes varies between species and is not clear in human. Moreover, several studies suggest that this distribution changes during the development and heart diseases. However, the consequences of NCX and PMCA redistribution in human ventricular cardiomyocytes have not yet been elucidated. In this study, we aimed to address this point by using a mathematical model of the human ventricular myocyte incorporating t-tubules, dyadic spaces, and subsarcolemmal spaces. Effects of various combinations of t-tubular fractions of NCX and PMCA were explored, using values between 0.2 and 1 as reported in animal experiments under normal and pathological conditions. Small variations in the action potential duration (≤ 2%), but significant changes in the peak value of cytosolic Ca2+ transient (up to 17%) were observed at stimulation frequencies corresponding to the human heart rate at rest and during activity. The analysis of model results revealed that the changes in Ca2+ transient induced by redistribution of NCX and PMCA were mainly caused by alterations in Ca2+ concentrations in the subsarcolemmal spaces and cytosol during the diastolic phase of the stimulation cycle. The results suggest that redistribution of both transporters between the t-tubular and surface membranes contributes to changes in contractility in human ventricular cardiomyocytes during their development and heart disease and may promote arrhythmogenesis.

Differential effects of stimulation frequency on isometric and concentric isotonic contractile function in human quadriceps.

Electrically evoked contractions are used to assess the relationship between frequency input and contractile output to characterize inherent muscle function, and these have been done mostly with isometric contractions (i.e., no joint rotation). The purpose was to compare the electrically stimulated frequency and contractile function relationship during isometric (i.e., torque) with isotonic (i.e., concentric torque, angular velocity, and mechanical power) contractions. The knee extensors of 16 (5 female) young recreationally active participants were stimulated (∼1-2.5 s) at 14 frequencies from 1 to 100 Hz. This was done during four conditions, which were isometric and isotonic at loads of 0 (unloaded), 7.5%, and 15% isometric maximal voluntary contraction (MVC), and repeated on separate days. Comparisons across contractile parameters were made as a % of 100 Hz. Independent of the load, the mechanical power-frequency relationship was rightward shifted compared with isometric torque-frequency, concentric torque-frequency, and velocity-frequency relationships (all P ≤ 0.04). With increasing load (0%-15% MVC), the isotonic concentric torque-frequency relationship was shifted leftward systematically from 15 to 30 Hz (all P ≤ 0.04). Conversely, the same changes in load caused a rightward shift in the velocity-frequency relationship from 1 to 40 Hz (all P ≤ 0.03). Velocity was leftward shifted of concentric torque in the unloaded isotonic condition from 10 to 25 Hz (all P ≤ 0.03), but concentric torque was leftward shifted of velocity at 15% MVC isotonic condition from 10 to 50 Hz (all P ≤ 0.03). Therefore, isometric torque is not a surrogate to evaluate dynamic contractile function. Interpretations of evoked contractile function differ depending on contraction type, load, and frequency, which should be considered relative to the specific task.NEW & NOTEWORTHY In whole human muscle, we showed that the electrically stimulated power-frequency relationship was rightward shifted of the stimulated isometric torque-frequency relationship independent of isotonic load, indicating that higher stimulation frequencies are needed to achieve tetanus. Therefore, interpretations of evoked contractile function differ depending on contraction type (isometric vs. dynamic), load, and frequency. And thus, isometric measures may not be appropriate as a surrogate assessment when evaluating dynamic isotonic contractile function.

Impact of optimized transcutaneous auricular vagus nerve stimulation on cardiac autonomic profile in healthy subjects and heart failure patients

Objective. To determine the optimal frequency and site of stimulation for transcutaneous vagus nerve stimulation (tVNS) to induce acute changes in the autonomic profile (heart rate (HR), heart rate variability (HRV)) in healthy subjects (HS) and patients with heart failure (HF). Approach. We designed three single-blind, randomized, cross-over studies: (1) to compare the acute effect of left tVNS at 25 Hz and 10 Hz (n = 29, age 60 ± 7 years), (2) to compare the acute effect of left and right tVNS at the best frequency identified in study 1 (n = 28 age 61 ± 7 years), and (3) to compare the acute effect of the identified optimal stimulation protocol with sham stimulation in HS and HF patients (n = 30, age 59 ± 5 years, and n = 32, age 63 ± 7 years, respectively). Main results. In study 1, left tragus stimulation at 25 Hz was more effective than stimulation at 10 Hz in decreasing HR (−1.0 ± 1.2 bpm, p < 0.001 and −0.5 ± 1.6 bpm, respectively) and inducing vagal effects (significant increase in RMSSD, and HF power). In study 2, the HR reduction was greater with left than right tragus stimulation (−0.9 ± 1.5 bpm, p < 0.01 and −0.3 ± 1.4 bpm, respectively). In study 3 in HS, left tVNS at 25 Hz significantly reduced HR, whereas sham stimulation did not (−1.1 ± 1.2 bpm, p< 0.01 and −0.2 ± 2.9 bpm, respectively). In HF patients, both active and sham stimulation produced negligible effects. Significance. Left tVNS at 25 Hz is effective in acute modulation of cardiovascular autonomic control (HR, HRV) in HS but not in HF patients (NCT05789147).

Low frequency of repetitive trans-spinal magnetic stimulation promotes functional recovery after spinal cord injury in mice through inhibiting TGF-β1/Smad2/3 signaling pathway

Spinal cord injury (SCI) remains a worldwide challenge due to limited treatment strategies. Repetitive trans-spinal magnetic stimulation (rTSMS) is among the most cutting-edge treatments for SCI. However, the mechanism underlying rTSMS on functional recovery is still unclear. In this study, 8-week-old C57BL/6J female mice were used to design SCI models followed by treatment with monotherapy (1 Hz rTSMS or LY364947) or combination therapy (rTSMS + LY364947). Our results showed obvious functional recovery after monotherapies compared to untreated mice. Immunofluorescence results demonstrated that rTSMS and LY364947 modulate the lesion scar by decreasing fibrosis and GFAP and possess the effect on neural protection. In addition, rTSMS suppressed inflammation and the activation of TGFβ1/Smad2/3 signaling pathway, as evidenced by markedly reduced TGF-βRⅠ, Smad2/3, and p-Smad2/3 compared with untreated mice. Overall, it was confirmed that 1 Hz rTSMS promotes SCI recovery by suppressing the TGFβ1/Smad2/3 signaling, revealing a novel pathological mechanism of 1 Hz rTSMS intervention, and may provide potential targets for clinical treatment.

Tonic Stimulation of Dorsal Root Ganglion Results in Progressive Decline in Recruitment of Aα/β-Fibers in Rats

ObjectivesIn this study, we aimed to characterize the recruitment and maintenance of action potential firing in Aα/β-fibers generated during tonic dorsal root ganglion stimulation (DRGS) applied over a range of clinically relevant stimulation parameters. Materials and MethodsWe delivered electrical stimulation to the L5 dorsal root ganglion and recorded antidromic evoked compound action potentials (ECAPs) in the sciatic nerve during DRGS in Sprague Dawley rats. We measured charge thresholds to elicit ECAPs in Aα/β-fibers during DRGS applied at multiple pulse widths (50, 150, 300, 500 μs) and frequencies (5, 20, 50, 100 Hz). We measured the peak-to-peak amplitudes, latencies, and widths of ECAPs generated during 180 seconds of DRGS, and excitation threshold changes to investigate potential mechanisms of ECAP suppression. ResultsTonic DRGS produced ECAPs in Aα/β-fibers at charge thresholds below the motor threshold. Increasing the pulse width of DRGS led to a significant increase in the charge required to elicit ECAPs in Aα/β-fibers, while varying DRGS frequency did not influence ECAP thresholds. Over the course of 180 seconds, ECAP peak-to-peak amplitude decreased progressively in a frequency-dependent manner, where 5- and 100-Hz DRGS resulted in 22% and 87% amplitude reductions, respectively, and ECAP latencies increased from baseline measurements during DRGS at 10, 20, 50, and 100 Hz. Regardless of DRGS frequency, ECAP amplitudes recovered within 120 seconds after turning DRGS off. We determined that ECAP suppression may be attributed to increasing excitation thresholds for individual fibers during DRGS. Following 180 seconds of DRGS, an average of 7.33% increase in stimulation amplitude was required to restore the ECAP to baseline amplitude. ConclusionsDRGS produces a progressive and frequency-dependent reduction in ECAP amplitude that occurs within and above the frequency range used clinically to relieve pain. If DRGS-mediated analgesia relies on Aβ-fiber activation, then the frequency or duty cycle of stimulation should be set to the lowest effective level to maintain sufficient activation of Aβ-fibers.

Non-invasive Transcutaneous Spinal Cord Stimulation Programming Recommendations for the Treatment of Upper Extremity Impairment in Tetraplegia

ObjectivesThis study analyzes the stimulation parameters implemented during two successful trials that used non-invasive transcutaneous spinal cord stimulation (tSCS) to effectively improve upper extremity function after chronic spinal cord injury (SCI). It proposes a framework to guide stimulation programming decisions for the successful translation of these techniques into the clinic. Materials and MethodsProgramming data from 60 participants who completed the Up-LIFT trial and from 17 participants who subsequently completed the LIFT Home trial were analyzed. All observations of stimulation amplitudes, frequencies, waveforms, and electrode configurations were examined. The incidence of adverse events and relatedness to stimulation parameters is reported. A comparison of parameter usage across the American Spinal Injury Association Impairment Scale (AIS) subgroups was conducted to evaluate stimulation strategies across participants with varying degrees of sensorimotor preservation. ResultsActive (cathodal) electrodes were typically placed between the C3/C4 and C6/C7 spinous processes. Most sessions featured return (anodal) electrodes positioned bilaterally over the anterior superior iliac spine, although clavicular placement was frequently used by 12 participants. Stimulation was delivered with a 10-kHz carrier frequency and typically a 30-Hz burst frequency. Biphasic waveforms were used in 83% of sessions. Average stimulation amplitudes were higher for biphasic waveforms. The AIS B subgroup required significantly higher amplitudes than did the AIS C and D subgroups. Device-related adverse events were infrequent, and not correlated with specific waveforms or amplitudes. Within the home setting, participants maintained their current amplitudes within 1% of the preset values. The suggested stimulation programming framework dictates the following hierarchical order of parameter adjustments: current amplitude, waveform type, active/return electrode positioning, and burst frequency, guided by clinical observations as required. ConclusionsThis analysis summarizes effective stimulation parameters from the trials and provides a decision-making framework for clinical implementation of tSCS for upper extremity functional restoration after SCI. The parameters are aligned with existing literature and proved safe and well tolerated by participants.

The protective effects of repetitive transcranial magnetic stimulation with different high frequencies on motor functions in MPTP/probenecid induced Parkinsonism mouse models.

High-frequency repeated transcranial magnetic stimulation (rTMS) stimulating the primary motor cortex (M1) is an alternative, adjunctive therapy for improving the motor symptoms of Parkinson's disease (PD). However, whether the high frequency of rTMS positively correlates to the improvement of motor symptoms of PD is still undecided. By controlling for other parameters, a disease animal model may be useful to compare the neuroprotective effects of different high frequencies of rTMS. The current exploratory study was designed to compare the protective effects of four common high frequencies of rTMS (5, 10, 15, and 20Hz) and iTBS (a special form of high-frequency rTMS) and explore the optimal high-frequency rTMS on an animal PD model. Following high frequencies of rTMS application (twice a week for 5weeks) in a MPTP/probenecid-induced chronic PD model, the effects of the five protocols on motor behavior as well as dopaminergic neuron degeneration levels were identified. The underlying molecular mechanisms were further explored. We found that all the high frequencies of rTMS had protective effects on the motor functions of PD models to varying degrees. Among them, the 10, 15, and 20Hz rTMS interventions induced comparable preservation of motor function through the protection of nigrostriatal dopamine neurons. The enhancement of brain-derived neurotrophic factor (BDNF), dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT-2)and the suppression of TNF-α and IL-1β in the nigrostriatum were involved in the process. The efficacy of iTBS was inferior to that of the above three protocols. The effect of 5Hz rTMS protocol was weakest. Combined with the results of the present study and the possible side effects induced by rTMS, we concluded that 10Hz might be the optimal stimulation frequency for preserving the motor functions of PD models using rTMS treatment.

Hybrid Brain-Computer Interface Controlled Soft Robotic Glove for Stroke Rehabilitation.

Soft robotic glove controlled by a brain-computer interface (BCI) have demonstrated effectiveness in hand rehabilitation for stroke patients. Current systems rely on static visual representations for patients to perform motor imagination (MI) tasks, resulting in lower BCI performance. Therefore, this study innovatively used MI and high-frequency steady-state visual evoked potential (SSVEP) to construct a friendly and natural hybrid BCI paradigm. Specifically, the stimulation interface sequentially presented decomposed action pictures of the left and right hands gripping a ball, with the pictures flashing at specific stimulation frequencies (left: 34 Hz, right: 35 Hz). Integrating soft robotic glove as feedback, we established a comprehensive "peripheral - central - peripheral" hand rehabilitation system to facilitate the hand rehabilitation of patients. Filter bank common spatial pattern (FBCSP) and filter bank canonical correlation analysis (FBCCA) algorithms were used to identify MI and SSVEP signals, respectively. Additionally, we proposed a novel fusion algorithm to decide the final output of the system. The feasibility of the proposed system was validated through online experiments involving 12 healthy subjects and 9 stroke patients, achieving accuracy rates of 95.83 ± 6.83% and 63.33 ± 10.38, respectively. The accuracy of MI and SSVEP in 12 healthy subjects reached 81.67 ± 15.63% and 95.14 ± 7.47%, both lower than the accuracy after fusion, these results confirmed the effectiveness of the proposed algorithm. The accuracy rate was more than 50% in both healthy subjects and patients, confirming the effectiveness of the proposed system.

Analisis Redaman Sistem Vibrasi Paksa Satu Derajat Kebebasan Pada Simple Vibration Apparatus

Vibration testing in the field of mechanical engineering has an important role in planning and maintaining machines to determine whether the design is safe and suitable for application. Newton's second law is a reference for back-and-forth movement around equilibrium both within the system and from outside the system which affects the machine itself, if the frequency of stimulation is equal to one of the system's natural frequencies, then resonance occurs, and dangerously large oscillations, resonance can cause damage to the system. The solution to avoid excessive resonance requires a damper. Forced vibration oscillations are applied by excitation using an unbalanced mass installed on a DC motor unit, the response is a mass deviation to obtain oscillations or time relationships with amplitude, the natural frequency of the system, mass-spring deviation, and characteristics of vibration. This activity aims to analyze the effect of the vibration amplitude of a forced vibration simulator under conditions without damping and using damping. The experimental test method was applied to a forced vibration system with one degree of freedom with an oil and air damper in a simple vibration apparatus simulator, 2 types of unbalanced masses, regulated by rotation up to 500rpm, tested under conditions without a damper, using an oil and air damper. The results of the activity showed that the air-dampening media can limit greater amplitude compared to the oil-dampening media.

Effect of electroacupuncture on myocardial transient receptor potential channels in mice with myocardial hypertrophy.

To observe the effect of electroacupuncture (EA) at "Neiguan"(PC6) on cardiac function, cardiac morphology and transient receptor potential channel (TRPC) protein expressions in myocardial tissue of mice with myocardial hypertrophy, so as to explore its mechanisms underlying improvement of myocardial hypertrophy. Forty-five male C57BL/6 mice were randomly divided into control, model and EA groups (15 mice/group). The myocardial hypertrophy model was established by subcutaneous injection of isoproterenol hydrochloride (15 mg·kg-1·d-1) for 14 days. The mice of the control group received subcutaneous injection of same amount of normal saline. The mice of the EA group received EA stimulation (frequency of 2 Hz, intensity of 1 mA) of bilateral PC6 for 20 min each time, once a day for 14 consecutive days. After the intervention, the body weight, tibia length and heart weight were measured. The left ventricular ejection fraction (EF), fractional shortening index (FS), left ventricular end-systolic volume (LVEV), left ventricular end-systolic internal diameter (LVID) and left ventricular posterior wall thickness (LVPW) were measured by using echocardiography for evaluating the cardiac function. The mean number and surface area of myocardial cells was detected by wheat germ agglutinin (WGA) staining, and changes of the cardiac morphology were observed under light microscopy after HE staining. The expression levels of TRPC1, TRPC3, TRPC4 and TRPC6 (TRPC1/3/4/6) in the myocardial tissue were detected by real-time quantitative PCR (qPCR) and Western blot, separately. Compared with the control group, the heart-body weight ratio(P<0.05) and heart-weight-to-tibia-length ratio (P<0.01), LVEV and LVID levels, the relative surface area, left ventricular area ratio, and the expression levels of cardiac TRPC1/3/4/6 were significantly increased (P<0.01, P<0.05), while the EF, FS, LVPW, number of cardiomyocytes, and the left ventricular posterior wall ratio were obviously decreased (P<0.01, P<0.05) in the model group. In comparison with the model group, the heart/body weight ratio, heart-weight-to-tibia-length ratio, LVEV and LVID levels, relative surface area, left ventricular area ratio, and the expression levels of cardiac TRPC1/3/4/6 were significantly decreased (P<0.01, P<0.05), while the EF, FS, LVPW, number of cardiomyocytes and left ventricular posterior wall ratio were significantly increased (P<0.01, P<0.05) in the EA group. H.E. staining showed disordered arrangement of cardiomyocytes and obvious myocardial interstitial inflammatory cell infiltration in the model group, and evident reduction of degree of cardiac fibrosis and interstitial edema in the EA group. EA of PC6 can improve the cardiac function and cardiac morphology in mice with myocardial hypertrophy, which may be related to its functions in down-regulating the expression of transient receptor potential channels.

Impaired Intracellular Calcium Buffering Contributes to the Arrhythmogenic Substrate in Atrial Myocytes From Patients With Atrial Fibrillation.

Alterations in the buffering of intracellular Ca2+, for which myofilament proteins play a key role, have been shown to promote cardiac arrhythmia. It is interesting that although studies report atrial myofibrillar degradation in patients with persistent atrial fibrillation (persAF), the intracellular Ca2+ buffering profile in persAF remains obscure. Therefore, we aimed to investigate the intracellular buffering of Ca2+ and its potential arrhythmogenic role in persAF. Transmembrane Ca2+ fluxes (patch-clamp) and intracellular Ca2+ signaling (fluo-3-acetoxymethyl ester) were recorded simultaneously in myocytes from right atrial biopsies of sinus rhythm (Ctrl) and patients with persAF, alongside human atrial subtype induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs). Protein levels were quantified by immunoblotting of human atrial tissue and induced pluripotent stem cell-derived cardiac myocytes. Mouse whole heart and atrial electrophysiology were measured on a Langendorff system. Cytosolic Ca2+ buffering was decreased in atrial myocytes of patients with persAF because of a depleted amount of Ca2+ buffers. In agreement, protein levels of selected Ca2+ binding myofilament proteins, including cTnC (cardiac troponin C), a major cytosolic Ca2+ buffer, were significantly lower in patients with persAF. Small interfering RNA (siRNA)-mediated knockdown of cTnC (si-cTNC) in atrial iPSC-CM phenocopied the reduced cytosolic Ca2+ buffering observed in persAF. Si-cTnC treated atrial iPSC-CM exhibited a higher predisposition to spontaneous Ca2+ release events and developed action potential alternans at low stimulation frequencies. Last, indirect reduction of cytosolic Ca2+ buffering using blebbistatin in an ex vivo mouse whole heart model increased vulnerability to tachypacing-induced atrial arrhythmia, validating the direct mechanistic link between impaired cytosolic Ca2+ buffering and atrial arrhythmogenesis. Our findings suggest that loss of myofilament proteins, particularly reduced cTnC protein levels, causes diminished cytosolic Ca2+ buffering in persAF, thereby potentiating the occurrence of spontaneous Ca2+ release events and atrial fibrillation susceptibility. Strategies targeting intracellular buffering may represent a promising therapeutic lead in persAF management.

Closed Loop Subject-Independent SSVEP Frequency Detection System Using CCA Features and Ensemble Learning Methods

Purpose: In recent years, the use of Steady-State Visual Evoked Potentials (SSVEPs) in Brain-Computer Interface (BCI) systems has dramatically increased across several fields, such as rehabilitation, cognitive impairment, and brain disease or disorder detection, as well as artificial limbs, wheelchairs, and biomechanical systems. In this study, a novel method is proposed to help scientists develop more efficient BCI systems for Machine Learning Operations (MLOps). This study proposed a state-of-the-art method for detecting SSVEP-based stimulation frequencies with statistical models to design an optimal BCI system. Materials and Methods: In this study, the Canonical Correlation Analysis (CCA) method has been implemented to extract features from the accessible-to-the-public Tsinghua University Benchmark dataset. A limited number of subjects are being studied. After completing feature selection methods and selecting the best subset of features using a specified feature selection method, the classification of the best features using machine learning-based classification methods has been completed. Furthermore, it is assumed that scientists will design and implement a system specifically for subjects. Models work for subjects independently. However, because model training is subject-specific, we must execute the proposed methods on each subject separately. Results: The findings indicate that the novel suggested BCI system achieves an average accuracy of 83±9% in stimulation detection, which is higher than that of the traditional CCA approach with an accuracy of 80±11% (p&lt;0.05). Conclusion: Based on the findings, we demonstrated an increase in accuracy with the novel method. It was also discovered that by using the proposed techniques, it is possible to keep MLOps systems as an advantage.

Neuro-cardiac-guided transcranial magnetic stimulation: Unveiling the modulatory effects of low-frequency and high-frequency stimulation on heart rate.

Transcranial magnetic stimulation (TMS) is pivotal in the field of major depressive disorder treatment. Due to its unsatisfied response rate, an increasing number of researchers have turned their attention towards optimizing TMS site localization. Since the influence of TMS in reducing heart rate (HR) offers insights into its regulatory impact on the autonomic nervous system, a novel approach, called neurocardiac-guided TMS (NCG-TMS), has been proposed to pinpoint the brain region eliciting the maximal individual reduction in HR as a personalized optimal stimulation target. The present study intends to systematically explore the effects of stimulation frequency, left and right hemispheres, stimulation positions, and individual differences on HR modulation using the NCG-TMS method. In experiment 1, low-frequency TMS was administered to 30 subjects, and it was found that low-frequency NCG-TMS significantly downregulated HR, with more significant effects in the right hemisphere than in the left hemisphere and the prefrontal cortex than in other brain areas. In experiment 2, high-frequency NCG-TMS stimulation was administered to 30 subjects, showing that high-frequency NCG-TMS also downregulated HR and had the greatest modulatory effect in the right prefrontal region. Simultaneously, both experiments revealed sizeable individual variability in the optimal stimulation site, which in turn validated the feasibility of the NCG-TMS method. In conclusion, the present experiments independently replicated the effect of NCG-TMS, provided an effect of high-/low-frequency TMS stimulation to downregulate HR, and identified a right lateralization of the HR modulation effect.

The use of neuromuscular electrical stimulation to elicit muscle contractions does not impair the hyperemic response compared to volitional contractions

Abstract Purpose Electrical stimulation-induced muscle contractions in individuals with paralyzed muscles are often associated with early onset fatigue. We examined whether electrical stimulation (ES) of the quadriceps muscle results in vasoconstriction and a reduction in blood flow which may contribute to this early onset fatigue. Methods Seventeen young individuals completed 40 ES isometric contractions (stimulation frequency of 75 Hz, pulse duration of 400 μs, on-off ratio 6.0-20s) and force matched voluntary (VOL) isometric contractions. Isometric force, heart rate, blood pressure, superficial femoral diameter and blood velocity were measured at baseline and during exercise (contractions 1,5,10,15,20,25,30,35, and 40). Net, antegrade, and retrograde blood flow, and conductance were quantified. Two-way, within-subjects ANOVAs were used to evaluate diameter, blood flow and conductance. Results Diameter was not different between ES and VOL (p = 0.57). Net blood flow increased during both conditions with the greatest blood flow occurring during ES compared to VOL (p ≤ 0.01). ES showed a greater increase antegrade and reduced retrograde flow compared to VOL. After the twentieth contraction, ES also elicited greater conductance than VOL (p ≤ 0.049). Conclusion The use of neuromuscular electrical stimulation to elicit muscle contractions does not result in vasoconstriction or a reduced hyperemic response compared to volitional contractions.

Evoked resonant neural activity long-term dynamics can be reproduced by a computational model with vesicle depletion

Subthalamic deep brain stimulation (DBS) robustly generates high-frequency oscillations known as evoked resonant neural activity (ERNA). Recently the importance of ERNA has been demonstrated through its ability to predict the optimal DBS contact in the subthalamic nucleus in patients with Parkinson's disease. However, the underlying mechanisms of ERNA are not well understood, and previous modelling efforts have not managed to reproduce the wealth of published data describing the dynamics of ERNA. Here, we aim to present a minimal model capable of reproducing the characteristics of the slow ERNA dynamics published to date. We make biophysically-motivated modifications to the Kuramoto model and fit its parameters to the slow dynamics of ERNA obtained from data. Our results demonstrate that it is possible to reproduce the slow dynamics of ERNA (over hundreds of seconds) with a single neuronal population, and, crucially, with vesicle depletion as one of the key mechanisms behind the ERNA frequency decay in our model. We further validate the proposed model against experimental data from Parkinson's disease patients, where it captures the variations in ERNA frequency and amplitude in response to variable stimulation frequency, amplitude, and to stimulation pulse bursting. We provide a series of predictions from the model that could be the subject of future studies for further validation.

A NEW POSTURAL MOTOR RESPONSE TO SPINAL CORD STIMULATION: POST-STIMULATION REBOUND EXTENSION.

Spinal cord stimulation (SCS) has emerged as a therapeutic tool for improving motor function following spinal cord injury. While many studies focus on restoring locomotion, little attention is paid to enabling standing which is a prerequisite of walking. In this study, we fully characterize a new type of response to SCS, a long extension activated post-stimulation (LEAP). LEAP is primarily directed to ankle extensors and hence has great clinical potential to assist postural movements. To characterize this new response, we used the decerebrate cat model to avoid the suppressive effects of anesthesia, and combined EMG and force measurement in the hindlimb with intracellular recordings in the lumbar spinal cord. Stimulation was delivered as five-second trains via bipolar electrodes placed on the cord surface, and multiple combinations of stimulation locations (L4 to S2), amplitudes (50-600 uA), and frequencies (10-40 Hz) were tested. While the optimum stimulation location and frequency differed slightly among animals, the stimulation amplitude was key for controlling LEAP duration and amplitude. To study the mechanism of LEAP, we performed in vivo intracellular recordings of motoneurons. In 70% of motoneurons, LEAP increased at hyperpolarized membrane potentials indicating a synaptic origin. Furthermore, spinal interneurons exhibited changes in firing during LEAP, confirming the circuit origin of this behavior. Finally, to identify the type of afferents involved in generating LEAP, we used shorter stimulation pulses (more selective for proprioceptive afferents), as well as peripheral stimulation of the sural nerve (cutaneous afferents). The data indicates that LEAP primarily relies on proprioceptive afferents and has major differences from pain or withdrawal reflexes mediated by cutaneous afferents. Our study has thus identified and characterized a novel postural motor response to SCS which has the potential to expand the applications of SCS for patients with motor disorders.

The effects of combining repetitive transcranial magnetic stimulation with task-specific training on gait performance in individuals with Parkinson's disease: A review article.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor impairments, especially in the area of gait disturbances. Physiotherapy, with a focus on task-specific training, has demonstrated a level of efficacy as regards alleviating symptoms and enhancing functional capabilities in individuals with PD. Repetitive Transcranial Magnetic Stimulation (rTMS) has emerged as a potential therapeutic intervention for improving motor functions in individuals with PD. This review article aims to investigate the effects of combining rTMS with task-specific training on gait performance in individuals with PD. PubMed, Physiotherapy Evidence Database (PEDro), and Scopus were all searched for relevant studies. The focus of the search was on studies that investigated the efficacy of combining rTMS with task-specific training to improve gait performance in individuals with PD. Four studies were identified as fulfilling the eligibility criteria and were included in the study. The combination of rTMS with specific treadmill training and weight-bearing exercises can significantly enhance walking efficiency, including improvements in walking speed, self-mobility, and step rate. In addition, the combination of rTMS and task-specific training, such as treadmill-based training, shows promise in enhancing gait performance in individuals with PD. High-frequency rTMS targeting the primary motor cortex (or M1) can result in improved walking speed, self-mobility, and step rate. However, limited research exists regarding low-frequency stimulation of the supplementary motor area (SMA) in individuals with gait issues. Further research is required to determine the optimal parameters of rTMS, such as strength, frequency, and duration of stimulation and it is worth considering the incorporation of additional training modalities, including cognitive exercises.