Name: Peripheral Electrical Stimulator Electrode Placement
Uploaded: 2023-04-21T14:45:00
Description: Watch this Scientific Journal Video about Peripheral Electrical Stimulator Electrode Placement at JoVE.com

peripheral electrical stimulator electrode placement

말초 신경 자극 및 제어 가능한 맥박 매개변수 TMS 결합

Multiple sensorimotor loops converge in the motor cortex to shape pyramidal tract projections to spinal motor neurons and interneurons1. However, how these sensorimotor loops interact to shape corticospinal projections and motor behavior remains an open question. Short-latency afferent inhibition (SAI) provides a tool to probe the functional properties of convergent sensorimotor loops in motor cortex output. SAI combines motor cortical transcranial magnetic stimulation (TMS) with electrical stimulation of the corresponding peripheral afferent nerve.
TMS is a non-invasive method to safely stimulate pyramidal motor neurons trans-synaptically in the human brain2,3. TMS involves passing a large, transient electric current through a coiled wire placed on the scalp. The transient nature of the electrical current creates a rapidly changing magnetic field that induces an electric current in the brain4. In the case of a single TMS stimulus, the induced current activates a series of excitatory inputs to the pyramidal motor neurons5-7. If the strength of the generated excitatory inputs is sufficient, the descending activity elicits a contralateral muscular response known as the motor-evoked potential (MEP). The latency of the MEP reflects the corticomotor conduction time8. The amplitude of the MEP indexes the excitability of the corticospinal neurons9. The single TMS stimulus that elicits the MEP can also be preceded by a conditioning stimulus10,11,12. These paired-pulse paradigms can be used to index the effects of various interneuron pools on the corticospinal output. In the case of SAI, the peripheral electrical conditioning stimulus is used to probe the impact of the afferent volley on the motor cortical excitability11,13,14,15. The relative timing of the TMS stimulus and peripheral electrical stimulation aligns the action of the TMS stimulus on the motor cortex with the arrival of the afferent projections to the motor cortex. For SAI in the distal upper limb muscles, the median nerve stimulus typically precedes the TMS stimulus by 18-24 ms11,13,15,16. At the same time, SAI increases as the strength of the afferent volley induced by the peripheral stimulus increases13,17,18.
Despite its strong association with the extrinsic properties of the afferent projection to the motor cortex, SAI is a malleable phenomenon implicated in many motor control processes. For example, SAI is reduced in task-relevant muscles before an impending movement19,20,21 but is maintained in adjacent task-irrelevant motor representations19,20,22. The sensitivity to task relevancy is hypothesized to reflect a surround inhibition mechanism23 that aims to reduce unwanted effector recruitment. More recently, it was proposed that the reduction in SAI in the task-relevant effector may reflect a movement-related gating phenomenon designed to suppress expected sensory afference21 and facilitate corrections during sensorimotor planning and execution24. Regardless of the specific functional role, SAI is correlated with reductions in manual dexterity and processing efficiency25. Altered SAI is also associated with an increased risk of falling in older adults26 and compromised sensorimotor function in Parkinson&#39;s disease26,27,28 and individuals with focal hand dystonia29.
Clinical and pharmacological evidence indicates that the inhibitory pathways mediating SAI are sensitive to central cholinergic modulation30. For example, administering the muscarinic acetylcholine receptor antagonist scopolamine reduces SAI31. In contrast, increasing the half-life of acetylcholine via acetylcholinesterase inhibitors enhances SAI32,33. Consistent with pharmacological evidence, SAI is sensitive to several cognitive processes with central cholinergic involvement, including arousal34, reward35, the allocation of attention21,36,37, and memory38,39,40. SAI is also altered in clinical populations with cognitive deficits associated with the loss of cholinergic neurons, such as Alzheimer&#39;s disease41,42,43,44,45,46,47, Parkinson&#39;s disease (with mild cognitive impairment)48,49,50, and mild cognitive impairment47,51,52. The differential modulation of SAI by various benzodiazepines with differential affinities for various &#947;-aminobutyric acid type A (GABAA) receptor subunit types suggests that the SAI inhibitory pathways are distinct from pathways mediating other forms of paired-pulse inhibition30. For example, lorazepam decreases SAI but enhances short-interval cortical inhibition (SICI)53. Zolpidem reduces SAI but has little effect on SICI53. Diazepam increases SICI but has little impact on SAI53. The reduction in SAI by these positive allosteric modulators of GABAA receptor function, coupled with the observation that GABA controls the release of acetylcholine in the brain stem and cortex54, has led to the hypothesis that GABA modulates the cholinergic pathway that projects to the sensorimotor cortex to influence SAI55.
Recently, SAI has been used to investigate interactions between the sensorimotor loops that set procedural motor control processes and those that align procedural processes to explicit top-down goals and cognitive control processes21,36,37,38. The central cholinergic involvement in SAI31 suggests that&#160;SAI may index an executive influence over procedural sensorimotor control and learning. Importantly, these studies have begun to identify the unique effects of cognition on specific sensorimotor circuits by assessing SAI using different TMS current directions. SAI studies typically employ posterior-anterior (PA) induced current, while only a handful of SAI studies have employed anterior-posterior (AP) induced current55. However, using TMS to induce AP compared with PA current during SAI assessment recruits distinct sensorimotor circuits16,56. For example, AP-sensitive, but not PA-sensitive, sensorimotor circuits are altered by cerebellar modulation37,56. Furthermore, AP-sensitive, but not PA-sensitive, sensorimotor circuits are modulated by attention load36. Finally, attention and cerebellar influences may converge on the same AP-sensitive sensorimotor circuits, leading to maladaptive alterations in these circuits37.
Advances in TMS technology provide additional flexibility to manipulate the configuration of the TMS stimulus employed during single-pulse, paired-pulse, and repetitive applications57,58. Controllable pulse parameter TMS (cTMS) stimulators are now commercially available for research use worldwide, and these provide flexible control over the pulse width and shape57. The increased flexibility arises from controlling the discharge duration of two independent capacitors, each responsible for a separate phase of the TMS stimulus. The biphasic or monophasic nature of the stimulus is governed by the relative discharge amplitude from each capacitor, a parameter called the M-ratio. cTMS studies have combined pulse width manipulation with different current directions to demonstrate that the fixed pulse widths used by conventional TMS stimulators (70-82 &#181;s)59,60 likely recruit a mix of functionally distinct sensorimotor circuits during SAI56. Therefore, cTMS is an exciting tool to disentangle further the functional significance of various convergent sensorimotor loops in sensorimotor performance and learning.
This manuscript details a unique SAI approach to studying sensorimotor integration that integrates peripheral electrical stimulation with cTMS during sensorimotor behaviors. This approach improves on the typical SAI approach by assessing the effect of afferent projections on select interneuron populations in the motor cortex that govern the corticospinal output during ongoing sensorimotor behavior. Although relatively new, cTMS provides a distinct advantage in studying sensorimotor integration in typical and clinical populations. Furthermore, the current approach can be easily adapted for use with conventional TMS stimulators and to quantify other forms of afferent inhibition and facilitation, such as long-latency afferent inhibition (LAI)13 or short-latency afferent facilitation (SAF)15.

저자 스포트라이트: Combined peripheral nerve stimulation and controllable pulse parameter Transcranial Magnetic Stimulation to Probe Sensorimotor Control and Learning  

말초 신경 자극 및 제어 가능한 펄스 매개변수 경두개 자기 자극을 결합하여 감각 운동 제어 및 학습을 조사합니다.

This technique provides insight into how sensory information is integrated into motor planning and execution. The implementation of controllable pulse parameter TMS enables us to identify specific sensory to motor pathways and how these pathways may be disrupted in neurological disorders. Motor scale acquisition and performance requires a fine balance between the conscious declarative and subconscious procedural process.Short latency afferent inhibition is a potential marker of how cognition may shape different procedural sensory motor circuits in the motor cortex of healthy and clinical populations. afferent inhibition quantifies the impact of afferent inputs on motor cortical output as elicited by transcranial magnetic stimulation. As a measure of sensory motor integration, it compliments functional magnetic resonance imaging and on electroencephalography by probing the contributions of specific neuronal populations on global hemodynamic and electrical responses elicited by skilled motor behavior.The lock parameters of magnetic stimuli generated by traditional transcranial magnetic stimulators recruit a mixture of sensory motor circuits. On the other hand, controllable pulse parameter transcranial magnetic stimulators unlock several stimulus parameters, enhancing the specificity of sensory motor circuits probed by afferent inhibition during skilled behavior. Assessing sensory motor inhibition during performance is critical to establishing markers of skilled and unskilled motor execution.Reliable and valid markers are an important step in developing enhanced models of motor control that will enhance or boost best practices in healthy populations, as well as minimize the impact of movement disorders through effective clinical interventions. Enhanced modeling of sensory motor circuits and the factors that influence their function can help provide objective markers of function and dysfunction that will inform best practices for motor performance, skill acquisition, and rehabilitation in both healthy and neurological populations. Continued definition of psychomotor and pharmacological influences over sensory motor circuits converging in motor cortex is critical.Combining afferent inhibition with electroencephalography provides an exciting opportunity to quantify afferent inhibition in non-motor areas as a marker of movement disorders and neuropsychiatric disorders.

Watch this Scientific Journal Video about Peripheral Electrical Stimulator Electrode Placement at JoVE.com

Peripheral Electrical Stimulator Electrode Placement  

주변 전기 자극기 전극 배치

시작하려면 약한 연마 크림을 사용하여 팔뚝 안쪽의 피부를 청소하십시오. 손목 굴곡 주름에서 시작하여 대략 근위부 6cm까지 확장됩니다. 손목 정중선에서 팔뚝의 반경 방향까지 청소를 확장합니다.알코올 준비 패드를 사용하여 잔여물을 닦아냅니다. 다음으로, 전도성 젤을 재사용 가능한 자극 막대 전극에 적용합니다. 양극 및 음극 접점의 금속 디스크를 덮을 수 있도록 충분한 젤을 사용하십시오.자극 전극을 양극에 근접한 음극과 함께 손목의 팔머 쪽에 놓습니다. 음극을 방사형 스타일로이드 프로세스의 약간 중간 및 근위부에 배치합니다. 말초 자극기에서 자극 유형 선택기 2 단상, 자극 지속 시간을 200 마이크로 초로 설정하고 적절한 전압과 암페어를 선택하여 곱셈 계수를 다시 확인하고 자극 전극을 유지하면서 정전류 자극기의 방아쇠 스위치를 눌러 단일 전기 자극을 전달합니다.그런 다음 abductor pollicis brevis 또는 APB 근육과 근전도 검사 또는 EMG 디스플레이를 육안으로 검사하여 근육 수축의 증거를 확인합니다. M 파라고도 알려진 근육 수축은 전기 자극에 의한 운동 축삭의 직접적인 활성화에 의해 유발되며 말초 전기 자극 인공물 후 6 밀리 초에서 9 밀리 초 사이에 발생해야합니다. 근육 수축의 증거가 없으면 참가자에게 손가락 쪽으로 또는 전극 바로 아래에서 발산되는 따끔거림을 느꼈는지 물어보십시오.참가자가 감각을 보고하지 않거나 전극 바로 아래 피부로 제한되는 경우 참가자가 손가락이나 엄지손가락까지 발산되는 따끔거림을 보고할 때까지 암페어를 0.05씩 늘립니다. 참가자가 엄지손가락이 아닌 다른 숫자로 방사 감각을 보고하면 느낌이 엄지손가락으로 방사될 때까지 전극을 방사형으로 움직여 전극의 위치를 변경합니다. 자극 전극의 최적 위치가 결정되면 세 개의 테이프를 사용하여 전극을 손목에 고정합니다.첫 번째 조각을 전극 중앙에 놓고 두 번째와 세 번째 조각을 사용하여 전극의 상단과 하단을 고정합니다. 전극을 고정한 후 참가자에게 TMS 자극 중에 사용할 원하는 사지 방향을 가정하도록 요청합니다. 엄지 손가락 경련이 여전히 유발되는지 확인하십시오.

Research

JoVE Journal

Neuroscience

Peripheral Electrical Stimulator Electrode Placement

Combined Peripheral Nerve Stimulation and Controllable Pulse Parameter Transcranial Magnetic Stimulation to Probe Sensorimotor Control and Learning

Skilled motor ability depends on efficiently integrating sensory afference into the appropriate motor commands. Afferent inhibition provides a valuable ...

연구

신경과학

﻿Participant Screening for Transcranial Magnetic Stimulation

Participant Screening for Transcranial Magnetic Stimulation  

경두개 자기 자극에 대한 참가자 스크리닝

Electromyography (EMG) Electrode Placement

근전도 검사(EMG) 전극 배치

Determination of Median Nerve Stimulus Intensity and Optimal Coil Trajectory for TMS