Frequency Of Nerve Stimulation 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.

Comparative Analysis on Machine Learning Approaches in Paralysis Disease Prediction

Machine learning approaches availability and its automated solutions improved precision and reproducibility of the execution of crucial activities in a variety of sectors, including radiology, diagnostics, and many others, where it is already having a significant impact. Paralysis occurs when people are unable to make voluntary muscle movements. Paralysis is caused by a problem with the nervous system. The main focus of this article is to explore the idea of building a Paralysis Prediction and Monitoring Model with the help of machine learning techniques. It is used to determine the frequency of nerve stimulation in the affected region as well as monitor the stimulus and paralysis-precipitating factors. It also highlights various machine learning algorithms like Decision tree, K-Nearest Neighbors, Support Vector Machine, Logistic regression, Random Forest functionality in prediction of paralysis occurrence with the help of a accuracy graph and showcase the best machine learning approach in prediction of paralysis disease with the help of comparative analysis.

Rat Model of Aerodigestive Dysfunction in Alzheimer’s Disease

AbstractBackgroundOral nutrition and aspiration pneumonia are significant factors impacting survival in patients with Alzheimer’s disease and related dementias (ADRD). Patients with ADRD demonstrate impairments to critical aerodigestive functions, including: prolonged oral phase durations, impaired masticatory performance, and prolonged swallow apnea durations. However, the pathophysiology underlying these functional changes is poorly understood. Establishing a translational model of swallowing dysfunction in ADRD will be critical for identifying underlying mechanisms of aerodigestive dysfunction and optimizing clinical treatments.MethodsAdult male TgF344‐AD rats (n = 6) and wild type rats (WT; n = 6) underwent videofluoroscopy (60 fps) to assess swallowing kinematics at 12 months of age. Jaw movement, bolus position, and diaphragm movement (proxy for respiration) were analyzed off‐line. All rats underwent a hypoglossal nerve electrical stimulation protocol, with the protruded tongue attached via small suture to a force transducer. All rats were stimulated maximally at a range of frequencies from 1 Hz – 140 Hz.ResultsThe AD group had significantly slower mastication rates (p = .037) and prolonged swallow apnea durations (p = .017) compared to WT. The AD group produced significantly lower forces at 60 Hz (p<.001) and 80 Hz (p<.001), indicating a higher frequency of nerve stimulation was required to elicit a given force of isometric tongue muscle contraction.ConclusionThe TgF344‐AD rat demonstrates functional mastication and swallowing decline consistent with clinical findings in patients with ADRD, with concomitant alterations in tongue muscle contractile properties and can serve as a valuable tool for interrogating biological and physiological mechanisms of aerodigestive dysfunction.

Optimizing Noninvasive Vagus Nerve Stimulation for Systemic Lupus Erythematosus: Protocol for a Multicenter Randomized Controlled Trial.

Systemic lupus erythematosus is a chronic, multisystem, inflammatory disease of autoimmune etiology occurring predominantly in women. A major hurdle to the diagnosis, treatment, and therapeutic advancement of this disease is its heterogeneous nature, which presents as a wide range of symptoms such as fatigue, fever, musculoskeletal involvement, neuropsychiatric disorders, and cardiovascular involvement with varying severity. The current therapeutic approach to this disease includes the administration of immunomodulatory drugs that may produce unfavorable secondary effects. This study explores the known relationship between the autonomic nervous system and inflammatory pathways to improve patient outcomes by treating autonomic nervous system dysregulation in patients via noninvasive vagus nerve stimulation. In this study, data including biomarkers, physiological signals, patient outcomes, and patient quality of life are being collected and analyzed. After completion of the clinical trial, a computer model will be developed to identify the biomarkers and physiological signals related to lupus activity in order to understand how they change with different noninvasive vagus nerve stimulation frequency parameters. Finally, we propose building a decision support system with integrated noninvasive wearable technologies for continuous cardiovascular and peripheral physiological sensing for adaptive, patient-specific optimization of the noninvasive vagus nerve stimulation frequency parameters in real time. The protocol was designed to evaluate the efficacy and safety of transauricular vagus nerve stimulation in patients with systemic lupus erythematosus. This multicenter, national, randomized, double-blind, parallel-group, placebo-controlled study will recruit a minimum of 18 patients diagnosed with this disease. Evaluation and treatment of patients will be conducted in an outpatient clinic and will include 12 visits. Visit 1 consists of a screening session. Subsequent visits up to visit 6 involve mixing treatment and evaluation sessions. Finally, the remaining visits correspond with early and late posttreatment follow-ups. On November 2022, data collection was initiated. Of the 10 participants scheduled for their initial appointment, 8 met the inclusion criteria, and 6 successfully completed the entire protocol. Patient enrollment and data collection are currently underway and are expected to be completed in December 2023. The results of this study will advance patient-tailored vagus nerve stimulation therapies, providing an adjunctive treatment solution for systemic lupus erythematosus that will foster adoption of technology and, thus, expand the population with systemic lupus erythematosus who can benefit from improved autonomic dysregulation, translating into reduced costs and better quality of life. ClinicalTrials.gov NCT05704153; https://clinicaltrials.gov/study/NCT05704153. DERR1-10.2196/48387.

Adenosine A2A Receptors Shut Down Adenosine A1 Receptor-Mediated Presynaptic Inhibition to Promote Implementation of Hippocampal Long-Term Potentiation.

Adenosine operates a modulation system fine-tuning the efficiency of synaptic transmission and plasticity through A1 and A2A receptors (A1R, A2AR), respectively. Supramaximal activation of A1R can block hippocampal synaptic transmission, and the tonic engagement of A1R-mediated inhibition is increased with increased frequency of nerve stimulation. This is compatible with an activity-dependent increase in extracellular adenosine in hippocampal excitatory synapses, which can reach levels sufficient to block synaptic transmission. We now report that A2AR activation decreases A1R-medated inhibition of synaptic transmission, with particular relevance during high-frequency-induced long-term potentiation (LTP). Thus, whereas the A1R antagonist DPCPX (50 nM) was devoid of effects on LTP magnitude, the addition of an A2AR antagonist SCH58261 (50 nM) allowed a facilitatory effect of DPCPX on LTP to be revealed. Additionally, the activation of A2AR with CGS21680 (30 nM) decreased the potency of the A1R agonist CPA (6-60 nM) to inhibit hippocampal synaptic transmission in a manner prevented by SCH58261. These observations show that A2AR play a key role in dampening A1R during high-frequency induction of hippocampal LTP. This provides a new framework for understanding how the powerful adenosine A1R-mediated inhibition of excitatory transmission can be controlled to allow the implementation of hippocampal LTP.

Artificial intelligence role in identifying paralysis with paralysis prediction and monitoring model

Computer vision, autonomous driving, natural language processing, and speech recognition are just a few of the industrial and research disciplines that are being transformed by Artificial Intelligence (AI) and Machine Learning (ML) approaches. The availability of automated solutions may improve the precision and reproducibility of the execution of crucial activities in a variety of sectors, including radiology, diagnostics, and many others, where it is already having a significant impact. Paralysis occurs when people are unable to make voluntary muscle movements. Paralysis is caused by a problem with the nervous system. This paper focuses on the study of the contribution of Artificial Intelligence in identifying paralysis and explores the idea of building a Paralysis Prediction and Monitoring Model (PPAMM) with the help of AI and ML techniques. It is used to determine the frequency of nerve stimulation in the affected region as well as monitor the stimulus and paralysis-precipitating factors.

Effectiveness of Dry Needling with Percutaneous Electrical Nerve Stimulation of High Frequency Versus Low Frequency in Patients with Myofascial Neck Pain

Percutaneous nerve electrical stimulation is a novel treatment modality for the management of acute and chronic myofascial pain syndrome. To compare the effectiveness of dry needling combined with percutaneous electrical nerve stimulation of low frequency versus high frequency, in patients with chronic myofascial neck pain. Randomized, single-blind trial. Laboratory in an academic institution. A total of 40 volunteer patients with chronic neck pain were randomly divided into 2 groups. All patients initially received deep dry needling in a myofascial trigger point of the upper trapezius. Then, one group received high frequency percutaneous electrical nerve stimulation while the other group received low frequency percutaneous electrical nerve stimulation. The primary outcomes were the visual analog scale and the pressure pain threshold, while Neck Disability Index and Kinesiophobia were secondary outcomes. We detected significant improvements in the visual analog scale score in both groups without differences between them. We did not observe significantly different statistics in either group during the evaluation of data on pressure pain threshold. Limitations of the study include (1) heterogeneity of the sample in relation to gender, with more women, (2) the small sample size (40 patients), (3) the absence of placebo group, and (4) the fact that the treatment is focused exclusively on the upper trapezium myofascial trigger point. . Low and high frequency percutaneous electrical nerve stimulation combined with deep dry needling showed similar effects, since no differences between groups were observed on any of the outcome measures. High and low frequency of percutaneous electrical nerve stimulation generates changes on pain intensity and disability, but not on pressure pain threshold or fear of movement.

Comparison of linear frequency and amplitude modulation for intraneural sensory feedback in bidirectional hand prostheses

Recent studies have shown that direct nerve stimulation can be used to provide sensory feedback to hand amputees. The intensity of the elicited sensations can be modulated using the amplitude or frequency of the injected stimuli. However, a comprehensive comparison of the effects of these two encoding strategies on the amputees’ ability to control a prosthesis has not been performed. In this paper, we assessed the performance of two trans-radial amputees controlling a myoelectric hand prosthesis while receiving grip force sensory feedback encoded using either linear modulation of amplitude (LAM) or linear modulation of frequency (LFM) of direct nerve stimulation (namely, bidirectional prostheses). Both subjects achieved similar and significantly above-chance performance when they were asked to exploit LAM or LFM in different tasks. The feedbacks allowed them to discriminate, during manipulation through the robotic hand, objects of different compliances and shapes or different placements on the prosthesis. Similar high performances were obtained when they were asked to apply different levels of force in a random order on a dynamometer using LAM or LFM. In contrast, only the LAM strategy allowed the subjects to continuously modulate the grip pressure on the dynamometer. Furthermore, when long-lasting trains of stimulation were delivered, LFM strategy generated a very fast adaptation phenomenon in the subjects, which caused them to stop perceiving the restored sensations. Both encoding approaches were perceived as very different from the touch feelings of the healthy limb (natural). These results suggest that the choice of specific sensory feedback encodings can have an effect on user performance while grasping. In addition, our results invite the development of new approaches to provide more natural sensory feelings to the users, which could be addressed by a more biomimetic strategy in the future.

Wake-promoting effects of vagus nerve stimulation after traumatic brain injury: upregulation of orexin-A and orexin receptor type 1 expression in the prefrontal cortex.

Orexins, produced in the lateral hypothalamus, are important neuropeptides that participate in the sleep/wake cycle, and their expression coincides with the projection area of the vagus nerve in the brain. Vagus nerve stimulation has been shown to decrease the amounts of daytime sleep and rapid eye movement in epilepsy patients with traumatic brain injury. In the present study, we investigated whether vagus nerve stimulation promotes wakefulness and affects orexin expression. A rat model of traumatic brain injury was established using the free fall drop method. In the stimulated group, rats with traumatic brain injury received vagus nerve stimulation (frequency, 30 Hz; current, 1.0 mA; pulse width, 0.5 ms; total stimulation time, 15 minutes). In the antagonist group, rats with traumatic brain injury were intracerebroventricularly injected with the orexin receptor type 1 (OX1R) antagonist SB334867 and received vagus nerve stimulation. Changes in consciousness were observed after stimulation in each group. Enzyme-linked immunosorbent assay, western blot assay and immunohistochemistry were used to assess the levels of orexin-A and OX1R expression in the prefrontal cortex. In the stimulated group, consciousness was substantially improved, orexin-A protein expression gradually increased within 24 hours after injury and OX1R expression reached a peak at 12 hours, compared with rats subjected to traumatic brain injury only. In the antagonist group, the wake-promoting effect of vagus nerve stimulation was diminished, and orexin-A and OX1R expression were decreased, compared with that of the stimulated group. Taken together, our findings suggest that vagus nerve stimulation promotes the recovery of consciousness in comatose rats after traumatic brain injury. The upregulation of orexin-A and OX1R expression in the prefrontal cortex might be involved in the wake-promoting effects of vagus nerve stimulation.

Comparison of Bladder Inhibitory Effects of Patterned Spinal Nerve Stimulation With Conventional Neuromodulation in the Rat

The present study compared the effectiveness of patterned frequency of spinal nerve stimulation (SNS) with continuous, fixed-frequency nerve stimulation in an animal model of the bladder reflex contraction (BRC). In anesthetized female rats, wire electrodes were placed under each of the L6 spinal nerve to produce bilateral SNS. A cannula was placed into the bladder via the urethra, and the urethra was ligated to ensure an isovolumetric bladder. Using motor threshold intensity, continuous stimulation at fixed frequencies of 4 Hz (n = 5) and 10 Hz (n = 7) decreased the frequency of BRC of 71 ± 24% (mean, SEM) and 85 ± 18% of controls, respectively (vs. no stimulation, n = 10, p < 0.05, two-way analysis of variance [ANOVA]). Fixed-frequency stimulation at 0.01, 0.1, 1, 40, and 100 Hz, did not demonstrate a trend change on BRC. When stimulation frequency is delivered with a 4-6 pulse/burst pattern every 1-100 sec, neuromodulation has demonstrated a trend toward effectiveness, with a four-pulse 40 Hz burst stimulation per second showing the most difference, reducing the BRC frequency of 74 ± 8% of control (n = 8, p < 0.05, two-way ANOVA). However, it is not more effective than continuous neuromodulation at a fixed frequency of 4 Hz or 10 Hz at BRC inhibition. Burst stimulations may inhibit bladder contractions; however, they are not more effective than continuous neuromodulation. Without further knowledge regarding mechanisms and potential benefit of burst stimulation on bladder control in patients with neuropathological conditions, applications should utilize continuous fixed 10 Hz stimulation for maximal clinical outcomes.

Targeted Transcutaneous Electrical Nerve Stimulation for Phantom Limb Sensory Feedback.

In this work, we investigated the use of noninvasive, targeted transcutaneous electrical nerve stimulation (TENS) of peripheral nerves to provide sensory feedback to two amputees, one with targeted sensory reinnervation (TSR) and one without TSR. A major step in developing a closed-loop prosthesis is providing the sense of touch back to the amputee user. We investigated the effect of targeted nerve stimulation amplitude, pulse width, and frequency on stimulation perception. We discovered that both subjects were able to reliably detect stimulation patterns with pulses less than 1 ms. We utilized the psychophysical results to produce a subject specific stimulation pattern using a leaky integrate and fire (LIF) neuron model from force sensors on a prosthetic hand during a grasping task. For the first time, we show that TENS is able to provide graded sensory feedback at multiple sites in both TSR and non-TSR amputees while using behavioral results to tune a neuromorphic stimulation pattern driven by a force sensor output from a prosthetic hand.

&lt;b&gt;Different frequencies of transcutaneous electrical nerve stimulation on sympatho-vagal balance

This study aims to evaluate the effects of TENS at different frequencies on autonomic balance in healthy volunteers. It is a case-control study, and was composed of fourteen healthy volunteers (5 women) with 28 (3.9) years old who underwent low (10 Hz 200ms -1 ) and high (100 Hz 200ms -1 ) frequency TENS. The interventions were randomized and applied for 30 minutes in the trajectory brachial nerve plexus from non-dominant member. Intensities were adjusted every 5 minutes and maintained below motor threshold. The autonomic balance was assessed before and after interventions by heart rate variability (HRV). TENS 10 Hz increased 10% sympathetic activity and decreased 10% parasympathetic activity; however, TENS 100 Hz showed opposite effects (p < 0.05). The sympatho-vagal balance increased with low frequency TENS and decreased with high frequency (p < 0.05). It can be concluded that different frequencies of TENS applied in the trajectory brachial nerve plexus modify cardiovascular autonomic responses. High frequency TENS reduces sympathetic activity and increases the parasympathetic, which favors beneficial effects on autonomic balance in healthy volunteers.

The transcutaneous electrical nerve stimulation of variable frequency intensity has a longer-lasting analgesic action than the burst transcutaneous electrical nerve stimulation in cancer pain

ABSTRACT BACKGROUND AND OBJECTIVES: Pain is one of the most frequent symptoms in cancer, and physical therapy offers non-invasive methods such as the transcutaneous electrical nerve stimulation for the relief of symptoms. The objective of this study was to compare the effect of the burst transcutaneous electrical nerve stimulation with the transcutaneous electrical nerve stimulation with variable intensity frequency in cancer pain. METHODS: This study was conducted with 53 patients of the Hospital Erasto Gaertner, divided into two groups: burst transcutaneous electrical nerve stimulation and variable intensity frequency transcutaneous electrical nerve stimulation. Pain assessment was performed before and right after the electroanalgesia, and at every hour until completing 6 hours. RESULTS: The group treated with burst transcutaneous electrical nerve stimulation maintained complete analgesia for 2 hours, returning to the initial score value within 6 hours of evaluation; the group of variable intensity frequency transcutaneous electrical nerve stimulation maintained complete analgesia for 4 hours, not returning to the initial score value within the 6 hours. When comparing the intensity of the pain between the groups there was a significant difference between them (p<0.001) in all the assessments from the third hour after the electroanalgesia, showing a significant difference (p<0.001) at the 3rd and 4th hour after the electroanalgesia. There was no difference at the 5th hour and at the 6th hour. CONCLUSION: The variable intensity frequency transcutaneous electrical nerve stimulation provided a longer-lasting analgesia in cancer pain than the burst transcutaneous electrical nerve stimulation.

Effect of 3,4-diaminopyridine at the murine neuromuscular junction.

We investigated the effects of 3,4-diaminopyridine (3,4-DAP) and its acetylated metabolite, N-(4-amino-pyridin-3-yl) acetamide (3-Ac), at the mammalian neuromuscular junction. Quantal release of acetylcholine was studied in diaphragm muscles of mice, using in vitro intracellular microelectrode recordings. Under conditions of low probability of release, 3,4-DAP produced a 1,000% increase in quantal release, but 3-Ac had no effect. Under conditions of normal probability of release, the effect of 3,4-DAP was modest and limited by concurrent depletion of synaptic vesicles, especially with high concentrations of 3,4-DAP and high frequencies of nerve stimulation. These findings predict 3,4-DAP is most effective in conditions with low probability of quantal release, such as Lambert-Eaton myasthenic syndrome. A beneficial effect is also expected in disorders of neuromuscular transmission in which the effect of 3,4-DAP on quantal release is not limited by depletion of synaptic vesicles, such as postsynaptic congenital myasthenic syndromes. Muscle Nerve, 2016 Muscle Nerve 55: 223-231, 2017.

Cytoskeletal Protein Septins Participate in the Modulation of the Kinetics of Acetylcholine Quanta Release at Neuromuscular Junction

In the presynaptic nerve terminal, some families of cytoskeletal proteins can participate in the neurosecretion modulation. Septins, GTP-binding cytoskeletal proteins, form hetero-oligomeric complexes both among themselves and with other synaptic proteins. Previously, it was reported that in the cell cultures, septins can interact with SNARE complex, NSF and SNAP-25, suggesting septin involvement in the exocytosis of neuromediator. Here, we describe effects of septin blockade on the time course of acetylcholine quantal release at mice neuromuscular junction under different frequency stimulation of motor nerve. Forchlorfenuron (FCF), a synthetic cytokinin, is the inhibitor of septin polymerization which specifically impairs assembly and disassembly of septin hetero-oligomers without affecting the actin or tubulin polymerization. FCF in the concentrations from 20 to 100 μM decreased the intensity of the spontaneous and evoked release of acetylcholine quanta. Block of septin dynamics resulted in changes in the kinetics of quantal release: the synchronization of quanta secretion was observed at low and high frequencies of nerve stimulation.

Long-term spinal cord stimulation modifies canine intrinsic cardiac neuronal properties and ganglionic transmission during high-frequency repetitive activation.

Long‐term spinal cord stimulation (SCS) applied to cranial thoracic SC segments exerts antiarrhythmic and cardioprotective actions in the canine heart in situ. We hypothesized that remodeling of intrinsic cardiac neuronal and synaptic properties occur in canines subjected to long‐term SCS, specifically that synaptic efficacy may be preferentially facilitated at high presynaptic nerve stimulation frequencies. Animals subjected to continuous SCS for 5–8 weeks (long‐term SCS: n = 17) or for 1 h (acute SCS: n = 4) were compared with corresponding control animals (long‐term: n = 15, acute: n = 4). At termination, animals were anesthetized, the heart was excised and neurones from the right atrial ganglionated plexus were identified and studied in vitro using standard intracellular microelectrode technique. Main findings were as follows: (1) a significant reduction in whole cell membrane input resistance and acceleration of the course of AHP decay identified among phasic neurones from long‐term SCS compared with controls, (2) significantly more robust synaptic transmission to rundown in long‐term SCS during high‐frequency (10–40 Hz) presynaptic nerve stimulation while recording from either phasic or accommodating postsynaptic neurones; this was associated with significantly greater posttrain excitatory postsynaptic potential (EPSP) numbers in long‐term SCS than control, and (3) synaptic efficacy was significantly decreased by atropine in both groups. Such changes did not occur in acute SCS. In conclusion, modification of intrinsic cardiac neuronal properties and facilitation of synaptic transmission at high stimulation frequency in long‐term SCS could improve physiologically modulated vagal inputs to the heart.

Effects of Direct Afferent Nerve Stimulation Frequency and Intensity In Evoking the Exercise Pressor Reflex

Contraction of freely perfused hind limb muscles in decerebrate rats evokes the exercise pressor reflex, resulting in sympathetic activation and increased blood pressure. This reflex is primarily propagated along mechanically sensitive group III and metabolically sensitive group IV afferent nerve fibers. Recent research by our laboratory has focused on the exaggeration of the exercise pressor reflex in decerebrate rats with simulated peripheral artery disease, which was induced by ligating the femoral artery for 72 hours before the start of the experiment. Recently, we showed that ligating the femoral artery increased the responses of single fiber group III and IV triceps surae muscle afferents to static contraction. The objective of the present study was to determine if electrical stimulation of group III and IV afferents at frequencies approximating those occurring during static contraction was capable of reflexively increasing arterial blood pressure.In decerebrate unanesthetized rats, we first determined motor threshold by gradually increasing the current applied as a single pulse (0.01 ms) to the gastrocnemius nerve until a twitch was evoked from the triceps surae muscles. Once motor threshold was determined, we injected intravenously pancuronium bromide to paralyze the rat for the remainder of the experiment. Five minutes later, we stimulated the sciatic nerve for 30 seconds at either 5, 20, or 100 times motor threshold, currents that presumably recruited thick group III, thick and thin group III, and all group III and IV fibers, respectively. In addition, we stimulated (0.01 ms pulse duration) the gastrocnemius nerves with six different frequencies (0.1, 0.25, 0.5, 1.0, 3.0, or 5.0 Hz), applying them in random order. Particular attention was paid to frequencies of 0.25, 0.5 and 1.0 Hz because these represented the discharge rates displayed by group III and IV afferents responding to static contraction.Overall, we found that stimulation of the gastrocnemius nerve increased arterial blood pressure in a graded fashion as both stimulus frequency and motor threshold were increased. In particular, stimulation of the gastrocnemius nerve at 100 times motor threshold (n=7) significantly increased arterial blood pressure (MAP) over baseline levels at 0.25 Hz (Peak ΔMAP= 11 ± 2 mmHg, p&lt; 0.001), 0.5 Hz (Peak ΔMAP= 13 ± 3 mmHg, p&lt; 0.01), and 1.0 Hz (Peak ΔMAP= 18 ± 4 mmHg, p&lt; 0.01).In conclusion, we observed that afferent stimulation frequencies as low as 0.25 Hz are sufficient to increase arterial blood pressure. These findings are relevant, as previous studies from our lab have measured afferent responses to contraction in these frequency ranges. Additionally, we observed that increasing stimulus frequency resulted in greater increases in blood pressure, a finding that parallels our previous results in studies using ligated rats. As such, these and future studies provide valuable insight into the mechanisms underlying the exaggerated exercise pressor reflex we observe in an animal model of peripheral artery disease.Support or Funding InformationFunded by NIH R01 ‐ AR059397

The Effect of Frequency of Transcutaneous Electrical Nerve Stimulation (TENS) on Maximum Multi-finger Force Production

Objective: The purpose of this study was to investigate the effect of transcutaneous electrical nerve stimulation (TENS) treatment on maximum voluntary force (MVF) production. Methods: Ten healthy, young subjects (5 males and 5 females) participated in the study. MVF was recorded after a fifteen minute session of TENS stimulation under two conditions: low frequency (4 Hz) at maximum tolerable level and high frequency (110 Hz) at maximum tolerable level. TENS was provided simultaneously via self-adhesive electrodes placed on the finger pads of the index, middle, ring and little fingers. MVF was also recorded in a baseline condition with no TENS treatment. Data were collected in three different sessions on three consecutive days at the sametime of the day. Results: Results from the study show that on an average, MVF increasesby 25% for the index, middle and little fingers for TENS treatment with 4 Hz frequency as compared to the baseline condition. However, the 110 Hz condition did not result in a significantly different MVF than the baseline condition during individual finger pressing tasks. In addition, while producing MVF with all the four finger stogether, MVF was 30% higher for the 4 Hz conditionin comparison to the baseline condition, and 15% higher for the 110 Hz condition in comparison to the baseline condition respectively. Conclusion: The results suggest that stimulation ofafferent fibers onthe glabrous skinwith TENS could have a net facilitatory effect on the maximum motoroutput.

The Influence of Vagus Nerve and Spinal Cord Stimulation on the Ictal Fast Ripple Activity in a Spike-and-Wave Rat Model of Seizures.

Fast ripple (FR) activity has received increasing attention as a potential epileptic marker. The current knowledge on how neurostimulation affects FRs is, however, very limited. In this study, we assess the influence of the vagus nerve stimulation (VNS) and spinal cord stimulation (SCS) frequency on ictal FRs associated with spike-and-wave (SW) seizures. SW discharges were induced and maintained by an infusion of pentylenetetrazol in rat. During ongoing SW seizures, SCS was conducted at 30, 80, 130, and 180 Hz and VNS at 10, 30, 80, 130, and 180 Hz. The FRs were derived from intracortical recordings and the FR rate was used for quantifying the level of FR activity. The FR rate was significantly correlated (r = 0.81) with the level of total pentylenetetrazol dose. Compared with no stimulation intervals, SCS conducted at 80, 130, and 180 Hz significantly reduced the normalized FR rate by 24, 38, and 44%, respectively. Similarly, VNS conducted at 30, 80, 130, and 180 Hz significantly reduced the normalized FR rate by 23, 40, 61, and 65%, respectively. In the present model of sustained SW seizures, the FR rate was proportional with the severity of the SW seizures. Both SCS and VNS attenuated the FR rate and this attenuation was consistently strongest at the higher stimulation frequencies. Our results suggest that SCS may induce some of the same antiepileptic effects as VNS.

Modulation of spinal inhibitory reflexes depends on the frequency of transcutaneous electrical nerve stimulation in spastic stroke survivors

Neurophysiological studies in healthy subjects suggest that increased spinal inhibitory reflexes from the tibialis anterior (TA) muscle to the soleus (SOL) muscle might contribute to decreased spasticity. While 50 Hz is an effective frequency for transcutaneous electrical nerve stimulation (TENS) in healthy subjects, in stroke survivors, the effects of TENS on spinal reflex circuits and its appropriate frequency are not well known. We examined the effects of different frequencies of TENS on spinal inhibitory reflexes from the TA to SOL muscle in stroke survivors. Twenty chronic stroke survivors with ankle plantar flexor spasticity received 50-, 100-, or 200-Hz TENS over the deep peroneal nerve (DPN) of the affected lower limb for 30 min. Before and immediately after TENS, reciprocal Ia inhibition (RI) and presynaptic inhibition of the SOL alpha motor neuron (D1 inhibition) were assessed by adjusting the unconditioned H-reflex amplitude. Furthermore, during TENS, the time courses of spinal excitability and spinal inhibitory reflexes were assessed via the H-reflex, RI, and D1 inhibition. None of the TENS protocols affected mean RI, whereas D1 inhibition improved significantly following 200-Hz TENS. In a time-series comparison during TENS, repeated stimulation did not produce significant changes in the H-reflex, RI, or D1 inhibition regardless of frequency. These results suggest that the frequency-dependent effect of TENS on spinal reflexes only becomes apparent when RI and D1 inhibition are measured by adjusting the amplitude of the unconditioned H-reflex. However, 200-Hz TENS led to plasticity of synaptic transmission from the antagonist to spastic muscles in stroke survivors.