Research on the influence of electrode position on the sensitivity field based on Ansoft Maxwell

Author(s):  
Jian Yang ◽  
Zhuotong Luo ◽  
Shi Liu
2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Michael D. Sunshine ◽  
Antonino M. Cassarà ◽  
Esra Neufeld ◽  
Nir Grossman ◽  
Thomas H. Mareci ◽  
...  

AbstractRespiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.


2020 ◽  
pp. 1-13
Author(s):  
Sendhil Govender ◽  
Sally M. Rosengren

BACKGROUND: The cervical vestibular evoked myogenic potential (cVEMP) can be affected by the recording parameters used to quantify the response. OBJECTIVE: We investigated the effects of electrode placement and montage on the variability and symmetry of sternocleidomastoid (SCM) contraction strength and cVEMP amplitude. METHODS: We used inter-side asymmetries in electrode placement to mimic small clinical errors in twenty normal subjects. cVEMPs were recorded at three active electrode sites and referred to the distal SCM tendon (referential montages: upper, conventional and lower). Additional bipolar montages were constructed offline to measure SCM contraction strength using closely-spaced electrode pairs (bipolar montages: superior, lower and outer). RESULTS: The conventional montage generally produced the largest cVEMP amplitudes (P <  0.001). SCM contraction strength was larger for referential montages than bipolar ones (P <  0.001). Inter-side electrode position errors produced large variations in cVEMP and SCM contraction strength asymmetries in some subjects, producing erroneous abnormal test results. CONCLUSION: Recording locations affect cVEMP amplitude and SCM contraction strength. In most cases, small changes in electrode position had only minor effects but, in a minority of subjects, the different montages produced large changes in cVEMP and contraction amplitudes and asymmetry, potentially affecting test outcomes.


2004 ◽  
Vol 32 (04) ◽  
pp. 631-640
Author(s):  
Dong-Myong Jeong ◽  
Yong-Heum Lee ◽  
Myeong Soo Lee

The precise selection and the identification of acupuncture points are essential for the diagnosis and treatment of patients in Oriental medicine. In this study, we have developed a meridian identification system using Single-Power Alternating Current (SPAC), which discriminates between true acupoints and non-acupoints. The SPAC system is not affected by skin resistance or pressure and is more accurate than the existing meridian location system, which uses direct current (DC) excitation current. The accuracy of the meridian location is ensured with the SPAC system because it has the highest sensitivity and the lowest effect on the human body. A microprocessor is used to enhance reliability and increase the accuracy of the SPAC measurements. Current distribution is displayed using an image that overlays the measured skin current on the body image. The positions of the acupoints are then displayed on the body image. This method visualizes the meridian by measuring skin current with an improved electrode using the acupoint discrimination system. A computer display shows the transmitted current as a color related to the electrode position. We demonstrated that by changing the point of measurement on the skin and tracing the electrode on the screen, it is possible to visualize acupoints and meridian phenomena using the color display.


2009 ◽  
Vol 40 (1) ◽  
pp. 37-41 ◽  
Author(s):  
Annie Dionne ◽  
Anthony Parkes ◽  
Beata Engler ◽  
Bradley V. Watson ◽  
Michael W. Nicolle

2021 ◽  
Vol 46 (4) ◽  
pp. 305-312
Author(s):  
John Tran ◽  
Philip Peng ◽  
Anne Agur ◽  
Nimish Mittal

Background and objectivesAcromial branches of the lateral pectoral and suprascapular nerves have been proposed as targets for diagnostic block and radiofrequency ablation to treat superior shoulder pain; however, the nerve capture rates of these procedures have not been investigated. The objectives of this study were to use dissection and 3D modeling technology to determine the course of these acromial branches, relative to anatomical landmarks, and to evaluate nerve capture rates using ultrasound-guided dye injection and lesion simulation.MethodsUltrasound-guided dye injections, targeting the superior surface of coracoid process and floor of supraspinous fossa, were performed (n=5). Furthermore, needles targeting the superior and posterior surfaces of the coracoid process were placed under ultrasound guidance to simulate needle electrode position (n=5). Specimens were dissected, digitized, and modeled to determine capture rates of acromial branches of lateral pectoral and suprascapular nerves.ResultsThe course of acromial branches of lateral pectoral and suprascapular nerves were documented. Dye spread capture rates: acromial branches of lateral pectoral and suprascapular nerves were captured in all specimens. Lesion simulation capture rates: (1) when targeting superior surface of coracoid process, the entire acromial branch of lateral pectoral nerve was captured in all specimens and (2) when targeting posterior surface of coracoid process, the acromioclavicular and bursal branches of acromial branch of suprascapular nerve were captured in all specimens; coracoclavicular branch was captured in 3/5 specimens.ConclusionsThis study supports the anatomical feasibility of ultrasound-guided targeting of the acromial branches of lateral pectoral and suprascapular nerves. Further clinical investigation is required.


2006 ◽  
Vol 95 (5) ◽  
pp. 3113-3128 ◽  
Author(s):  
Carl Gold ◽  
Darrell A. Henze ◽  
Christof Koch ◽  
György Buzsáki

Although extracellular unit recording is typically used for the detection of spike occurrences, it also has the theoretical ability to report about what are typically considered intracellular features of the action potential. We address this theoretical ability by developing a model system that captures features of experimentally recorded simultaneous intracellular and extracellular recordings of CA1 pyramidal neurons. We use the line source approximation method of Holt and Koch to model the extracellular action potential (EAP) voltage resulting from the spiking activity of individual neurons. We compare the simultaneous intracellular and extracellular recordings of CA1 pyramidal neurons recorded in vivo with model predictions for the same cells reconstructed and simulated with compartmental models. The model accurately reproduces both the waveform and the amplitude of the EAPs, although it was difficult to achieve simultaneous good matches on both the intracellular and extracellular waveforms. This suggests that accounting for the EAP waveform provides a considerable constraint on the overall model. The developed model explains how and why the waveform varies with electrode position relative to the recorded cell. Interestingly, each cell's dendritic morphology had very little impact on the EAP waveform. The model also demonstrates that the varied composition of ionic currents in different cells is reflected in the features of the EAP.


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