scholarly journals Navigated transcranial magnetic stimulation of the primary somatosensory cortex evokes motor potentials in healthy humans’ flexor carpi radialis muscle - A pilot study

2020 ◽  
Vol 14 (3) ◽  
pp. 110-120
Author(s):  
János Négyesi ◽  
Takayuki Mori ◽  
Kouta Ataka ◽  
Shinichi Izumi ◽  
Tibor Hortobágyi ◽  
...  
Keyword(s):  
Single Pulse ◽  
Magnetic Pulse ◽  
Navigated Transcranial Magnetic Stimulation ◽  
Future Studies ◽  
Corticospinal Pathway ◽  
Healthy Humans ◽  
Neuronavigation System ◽  
The Magnetic Field ◽  
Flexor Carpi Radialis Muscle ◽  
Stimulation Of

Background: Although previous studies targeted S1 by TMS to investigate its effect on the corticospinal pathway, there is no evidence if such stimuli produced by TMS would distinctly be restricted to it and not reach M1 interneurons adjacent to S1.Aim: We hypothesized that S1 vs. M1 stimulation-induced MEPs would be similar but smaller and less variable due to the focality of the magnetic pulse, considering that even if TMS is neuronavigated, the magnetic field is not selective enough and reaches M1 interneurons.Method: Healthy volunteers (n = 8, 2 females, age: 29.9 ± 5.49y) received single-pulse TMS over each hemisphere at each intensity of 90, 100, 110, and 120% of rMT in a randomized order. MEPs from the contralateral FCR were recorded.Results: We found no interhemispheric differences, but larger peak-to-peak amplitudes and variability of MEPs after M1 as compared to S1 stimulation. However, latency and waveforms of MEPs did not differ between S1 vs. M1 stimulation supporting the idea that TMS over S1 is not selective enough and can excite M1 interneurons thus producing MEPs on the contralateral FCR.Interpretation: Future studies should carefully consider these results when targeting S1 with TMS even if using a neuronavigation system.

Experimental investigation and optimization on field shaper structure parameters in magnetic pulse welding

2021 ◽  
pp. 095440542110148
Author(s):  
Yingzi Chen ◽  
Zhiyuan Yang ◽  
Wenxiong Peng ◽  
Huaiqing Zhang
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Light Metal ◽  
Magnetic Pulse ◽  
Cross Sectional ◽  
Magnetic Pulse Welding ◽  
Pulse Welding ◽  
Sectional Shape ◽  
Welding System ◽  
The Magnetic Field

Magnetic pulse welding is a high-speed welding technology, which is suitable for welding light metal materials. In the magnetic pulse welding system, the field shaper can increase the service life of the coil and contribute to concentrating the magnetic field in the welding area. Therefore, optimizing the structure of the field shaper can effectively improve the efficiency of the system. This paper analyzed the influence of cross-sectional shape and inner angle of the field shaper on the ability of concentrating magnetic field via COMSOL software. The structural strength of various field shapers was also analyzed in ABAQUS. Simulation results show that the inner edge of the field shaper directly affects the deformation and welding effect of the tube. So, a new shape of field shaper was proposed and the experimental results prove that the new field shaper has better performance than the conventional field shaper.

scholarly journals The Connectivity Index: An Effective Metric for Grading Epileptogenicity

2019 ◽  
Author(s):  
Qi Yan ◽  
Nicolas Gaspard ◽  
Hitten P Zaveri ◽  
Hal Blumenfeld ◽  
Lawrence J. Hirsch ◽  
...  
Keyword(s):  
Average Distance ◽  
Single Pulse ◽  
Brain Regions ◽  
Control Site ◽  
Connectivity Index ◽  
Evoked Responses ◽  
Seizure Onset ◽  
Seizure Onset Zone ◽  
Site Of Stimulation ◽  
Stimulation Of

AbstractObjectiveTo investigate the performance of a metric of functional connectivity to classify and grade the excitability of brain regions based on evoked potentials to single pulse electrical stimulation (SPES).MethodsPatients who received 1-Hz frequency stimulation between 2003 and 2014 at Yale at prospectively selected contacts were included. The stimulated contacts were classified as seizure onset zone (SOZ), highly irritative zone (IZp) or control. Response contacts were classified as seizure onset zone (SOZ), active interictal (IZp), quiet or other. The normalized number of responses was defined as the number of contacts with any evoked responses divided by the total number of recorded contacts, and the normalized distance is the ratio of the average distance between the site of stimulation and sites of evoked responses to the average distances between the site of stimulation and all other recording contacts. A new metric we labeled the connectivity index (CI) is defined as the product of the two values.Results57 stimulation-sessions in 22-patients were analyzed. The connectivity index (CI) of the SOZ was higher than control (median CI of 0.74 vs. 0.16, p = 0.0002). The evoked responses after stimulation of SOZ were seen at further distance compared to control (median normalized distance 0.96 vs. 0.62, p = 0.0005). It was 1.8 times more likely to record a response at SOZ than in non-epileptic contacts after stimulation of a control site. Habitual seizures were triggered in 27% of patients and 35 % of SOZ contacts (median stimulation intensity 4 mA) but in none of the control or IZp contacts. Non-SOZ contacts in multifocal or poor surgical outcome cases had a higher CI than non-SOZ contacts in those with localizable onsets (medians CI of 0.5 vs. 0.12, p = 0.04). There was a correlation between the stimulation current intensity and the normalized number of evoked responses (r = + 0.49, p 0.01) but not with distance (r = + 0.1, p 0.64)ConclusionsWe found enhanced connectivity when stimulating the SOZ compared to stimulating control contacts; responses were more distant as well. Habitual auras and seizures provoked by SPES were highly predictive of brain sites involved in seizure generation.

Neuromuscular adaptations to healthy aging

2018 ◽  
Vol 43 (11) ◽  
pp. 1158-1165 ◽  
Author(s):  
Chris J. McNeil ◽  
Charles L. Rice
Keyword(s):  
Daily Living ◽  
Healthy Aging ◽  
The Elderly ◽  
Neuromuscular System ◽  
Healthy Humans ◽  
Age Related ◽  
Physiological Adaptations ◽  
Neuromuscular Adaptations ◽  
The Central Nervous System ◽  
Stimulation Of

Even in the absence of disease or disability, aging is associated with marked physiological adaptations within the neuromuscular system. An ability to perform activities of daily living and maintain independence with advanced age is reliant on the health of the neuromuscular system. Hence, it is critical to elucidate the age-related adaptations that occur within the central nervous system and the associated muscles to design interventions to maintain or improve neuromuscular function in the elderly. This brief review focuses on the neural alterations observed at both spinal and supraspinal levels in healthy humans in their seventh decade and beyond. The topics addressed are motor unit loss and remodelling, neural drive, and responses to transcranial magnetic stimulation of the motor cortex.

Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris

1974 ◽  
Vol 60 (2) ◽  
pp. 453-467
Author(s):  
C. D. DREWES ◽  
R. A. PAX
Keyword(s):  
Time Course ◽  
Longitudinal Muscle ◽  
Lumbricus Terrestris ◽  
Single Pulse ◽  
Repetitive Stimulation ◽  
Muscle Fibres ◽  
Mechanical Responses ◽  
Segmental Nerve ◽  
Earthworm Lumbricus ◽  
Stimulation Of

1. Patterns of innervation of the longitudinal muscle of the earthworm, Lumbricus terrestris, were examined electrophysiologically. 2. The longitudinal musculature of a segment is innervated by relatively few axons, a fast and slow axon being present in segmental nerve I and in the double nerve, segmental nerve II-III. 3. Single-pulse stimulation of the fast axon produces large external muscle potentials and small twitch-like contractions, which with repetitive stimulation are antifacilitating. 4. Repetitive stimulation of the slow axon produces large, slowly developing and sustained mechanical responses, with electrical and mechanical responses showing summation and facilitation. 5. The amplitude and time course of slow mechanical responses are related to the frequency of stimulation. 6. Individual longitudinal muscle fibres are innervated by either the fast or slow axon in a segmental nerve, or by both fast and slow axons. 7. No evidence was found for peripheral inhibitory innervation of the longitudinal muscle.

Robust Changes of Afferent-Induced Excitation in the Rat Spinal Dorsal Horn After Conditioning High-Frequency Stimulation

2000 ◽  
Vol 83 (4) ◽  
pp. 2412-2420 ◽  
Author(s):  
Hiroshi Ikeda ◽  
Tatsuya Asai ◽  
Kazuyuki Murase
Keyword(s):  
Dorsal Horn ◽  
High Frequency ◽  
Low Frequency ◽  
Single Pulse ◽  
High Frequency Stimulation ◽  
Neuronal Excitation ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation ◽  
Stimulation Of

We investigated the neuronal plasticity in the spinal dorsal horn and its relationship with spinal inhibitory networks using an optical-imaging method that detects neuronal excitation. High-intensity single-pulse stimulation of the dorsal root activating both A and C fibers evoked an optical response in the lamina II (the substantia gelatinosa) of the dorsal horn in transverse slices of 12- to 25-day-old rat spinal cords stained with a voltage-sensitive dye, RH-482. The optical response, reflecting the net neuronal excitation along the slice-depth, was depressed by 28% for more than 1 h after a high-frequency conditioning stimulation of A fibers in the dorsal root (3 tetani of 100 Hz for 1 s with an interval of 10 s). The depression was not induced in a perfusion solution containing an NMDA antagonist,dl-2-amino-5-phosphonovaleric acid (AP5; 30 μM). In a solution containing the inhibitory amino acid antagonists bicuculline (1 μM) and strychnine (3 μM), and also in a low Cl−solution, the excitation evoked by the single-pulse stimulation was enhanced after the high-frequency stimulation by 31 and 18%, respectively. The enhanced response after conditioning was depotentiated by a low-frequency stimulation of A fibers (0.2–1 Hz for 10 min). Furthermore, once the low-frequency stimulation was applied, the high-frequency conditioning could not potentiate the excitation. Inhibitory transmissions thus regulate the mode of synaptic plasticity in the lamina II most likely at afferent terminals. The high-frequency conditioning elicits a long-term depression (LTD) of synaptic efficacy under a greater activity of inhibitory amino acids, but it results in a long-term potentiation (LTP) when inhibition is reduced. The low-frequency preconditioning inhibits the potentiation induction and maintenance by the high-frequency conditioning. These mechanisms might underlie robust changes of nociception, such as hypersensitivity after injury or inflammation and pain relief after electrical or cutaneous stimulation.

Stimulation of myocardial coenzyme A degradation by fatty acids

1987 ◽  
Vol 253 (1) ◽  
pp. H41-H46
Author(s):  
G. D. Lopaschuk ◽  
J. R. Neely
Keyword(s):  
Fatty Acids ◽  
Coenzyme A ◽  
Future Studies ◽  
Isolated Hearts ◽  
Tissue Content ◽  
Chain Acyl ◽  
Long Chain ◽  
Stimulation Of

Coenzyme A (CoA) levels were increased in isolated hearts from 537 +/- 14 to 818 +/- 44 nmol/g dry wt by perfusion for 45 min under conditions known to stimulate CoA synthesis (5). Subsequently, perfusion of these hearts with buffer containing glucose (11 mM) and pyruvate (5 mM) for 3 min had no effect on CoA levels (789 +/- 42 nmol/g dry wt). However, perfusion with a buffer containing glucose (11 mM) and palmitate (1.2 mM) decreased CoA levels to 683 +/- 34 nmol/g dry wt within 3 min. This decrease in CoA appeared to occur in the cytosolic compartment with no change in mitochondrial CoA content and was associated with a rise in tissue content of long-chain acyl-CoA. An increased incorporation of fatty acids into triglycerides was associated with the rise in total acyl-CoA suggesting that long-chain acyl-CoA levels were elevated in the cytosolic compartment. Perfusion conditions which maximally increased acyl-CoA levels also maximally stimulated CoA degradation. These observations suggest that the cytosolic degradation of CoA is related to high levels of long-chain acyl-CoA in this compartment. Use of these perfusion conditions in future studies should help define the pathway of CoA degradation and determine the mechanisms which control cellular levels of CoA.

Stimulation of angiogenesis using single-pulse low-pressure shock wave treatment

2018 ◽  
Vol 96 (11) ◽  
pp. 1177-1187 ◽  
Author(s):  
Susinder Sundaram ◽  
Karthi Sellamuthu ◽  
Krishnaveni Nagavelu ◽  
Harikumar R Suma ◽  
Arpan Das ◽  
...  
Keyword(s):  
Shock Wave ◽  
Single Pulse ◽  
Low Pressure ◽  
Pressure Shock ◽  
Wave Treatment ◽  
Shock Wave Treatment ◽  
Stimulation Of

Sympatholytic response to stimulation of superior laryngeal nerve in rats

1991 ◽  
Vol 260 (2) ◽  
pp. R290-R297 ◽  
Author(s):  
D. H. Huangfu ◽  
P. G. Guyenet
Keyword(s):  
Receptor Antagonist ◽  
Superior Laryngeal Nerve ◽  
Single Pulse ◽  
Laryngeal Nerve ◽  
Ventrolateral Medulla ◽  
Gamma Aminobutyric Acid ◽  
Onset Latency ◽  
Medullary Reticular Formation ◽  
Pulse Stimulation ◽  
Stimulation Of

The central pathway mediating a sympatholytic response to stimulation of the superior laryngeal nerve (SLN) was studied in halothane-anesthetized, paralyzed rats. Single-pulse stimulation of SLN inhibited lumbar sympathetic nerve discharge (LSND) with onset latency of 113 +/- 1.7 ms. LSND inhibition was markedly attenuated by bilateral microinjection of kynurenic acid (Kyn, glutamate receptor antagonist, 4.5 nmol/side) into the caudal ventrolateral medulla (CVL) or by bilateral administration of bicuculline methiodide (Bic; gamma-aminobutyric acid-receptor antagonist, 225 pmol/side) into the rostral ventrolateral medulla (RVL). In 13 of 14 cases, the baroreceptor reflex was also severely reduced. Injections of Bic or Kyn elsewhere in the medullary reticular formation were ineffective. Single-pulse stimulation of SLN inhibited 19 of 26 RVL reticulospinal barosensitive cells (onset latency 46 +/- 1.4 ms). This inhibition was attenuated (from 92 +/- 6 to 14 +/- 12%) by iontophoretic application of Bic (n = 7), which also reduced the cells' inhibitory response to aortic coarctation. The remaining seven barosensitive neurons were unaffected by SLN stimulation. In conclusion, the sympathetic baroreflex and the sympathoinhibitory response to SLN stimulation appear to be mediated by similar medullary pathways.

scholarly journals Magnetic Field Measurements during Magnetic Pulse Welding Using CMR-B-Scalar Sensors

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5925
Author(s):  
Voitech Stankevic ◽  
Joern Lueg-Althoff ◽  
Marlon Hahn ◽  
A. Erman Tekkaya ◽  
Nerija Zurauskiene ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Colossal Magnetoresistance ◽  
Welding Process ◽  
Nondestructive Method ◽  
Magnetic Field Measurement ◽  
Magnetic Pulse ◽  
Magnetic Pulse Welding ◽  
Pulse Welding ◽  
The Magnetic Field

The possibility of applying CMR-B-scalar sensors made from thin manganite films exhibiting the colossal magnetoresistance effect as a fast-nondestructive method for the evaluation of the quality of the magnetic pulse welding (MPW) process is investigated in this paper. This method based on magnetic field magnitude measurements in the vicinity of the tools and joining parts was tested during the electromagnetic compression and MPW of an aluminum flyer tube with a steel parent. The testing setup used for the investigation allowed the simultaneous measurement of the flyer displacement, its velocity, and the magnitude of the magnetic field close to the flyer. The experimental results and simulations showed that, during the welding of the aluminum tube with the steel parent, the maximum magnetic field in the gap between the field shaper and the flyer is achieved much earlier than the maximum of the current pulse of the coil and that the first half-wave pulse of the magnetic field has two peaks. It was also found that the time instant of the minimum between these peaks depends on the charging energy of the capacitors and is associated with the collision of the flyer with the parent. Together with the first peak maximum and its time-position, this characteristic could be an indication of the welding quality. These results were confirmed by simultaneous measurements of the flyer displacement and velocity, as well as a numerical simulation of the magnetic field dynamics. The relationship between the peculiarities of the magnetic field pulse and the quality of the welding process is discussed. It was demonstrated that the proposed method of magnetic field measurement during magnetic pulse welding in combination with subsequent peel testing could be used as a nondestructive method for the monitoring of the quality of the welding process.

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