The effect of stimulus current pulse width on nerve fiber size recruitment patterns

Szlavik, Robert B.; Bruin, Hubert de

doi:10.1016/s1350-4533(99)00074-0

Cited by 36 publications

(45 citation statements)

References 17 publications

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“…It has been shown that at different stimulus pulse widths, the nerve fibers recruited by the stimuli were also different. 29 A typical example is that peripheral sensory fibers are more effectively evoked with longer pulse width than motor fibers. 30 Our fMRI data showed that the cS1 CBV response exhibited two phases during pulse-width modulation: in phase 1, the responses increased with pulse width and peaked B3 milliseconds.…”

Section: Neurovascular Responses In the Striatummentioning

confidence: 99%

Imaging Neurovascular Function and Functional Recovery after Stroke in the Rat Striatum Using Forepaw Stimulation

Shih

Huang

Lai

et al. 2014

J Cereb Blood Flow Metab

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Negative functional magnetic resonance imaging (fMRI) response in the striatum has been observed in several studies during peripheral sensory stimulation, but its relationship between local field potential (LFP) remains to be elucidated. We performed cerebral blood volume (CBV) fMRI and LFP recordings in normal rats during graded noxious forepaw stimulation at nine stimulus pulse widths. Albeit high LFP-CBV correlation was found in the ipsilateral and contralateral sensory cortices (r ¼ 0.89 and 0.95, respectively), the striatal CBV responses were neither positively, nor negatively correlated with LFP (r ¼ 0.04), demonstrating that the negative striatal CBV response is not originated from net regional inhibition. To further identify whether this negative CBV response can serve as a marker for striatal functional recovery, two groups of rats (n ¼ 5 each) underwent 20-and 45-minute middle cerebral artery occlusion (MCAO) were studied. No CBV response was found in the ipsilateral striatum in both groups immediately after stroke. Improved striatal CBV response was observed on day 28 in the 20-minute MCAO group compared with the 45-minute MCAO group (Po0.05). This study shows that fMRI signals could differ significantly from LFP and that the observed negative CBV response has potential to serve as a marker for striatal functional integrity in rats.

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Section: Neurovascular Responses In the Striatummentioning

confidence: 99%

Imaging Neurovascular Function and Functional Recovery after Stroke in the Rat Striatum Using Forepaw Stimulation

Shih

Huang

Lai

et al. 2014

J Cereb Blood Flow Metab

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show abstract

“…Increasing the PA produces a stronger depolarising drive that travels deeper into the underlying tissue [23] and recruits a greater number of motor units, [16] whereas adjusting the PD influences not only the number of recruited motor units, but may also influence the selectivity of motor unit recruitment, due to threshold differences that exist between axons of different diameter lying at the same distance from the stimulating electrodes. [24][25][26] Thus, it may be possible to apply different combinations of PA and PD that generate contractions of equivalent torque, yet differing fatigue-resistance, through the activation of somewhat separate populations of motor units based on differences in the location, and threshold, of axons relative to the FES electrodes. With this in mind, the purpose of the present experiments was to determine whether optimal PA and PD combinations (i.e., optimal (PA,PD) pairs), those that minimize fatigue, differ for separate levels of generated torque.…”

Section: Introductionmentioning

confidence: 99%

Minimizing muscle fatigue through optimization of electrical stimulation parameters

Rouhani

Rodriguez

Bergquist

et al. 2016

JBEI

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Rapid onset of muscle fatigue in response to electrical stimulation is a major challenge when designing a neuroprosthesis. This study aimed to introduce a decision-making algorithm to optimize pulse amplitude and pulse duration, for current regulated electrical stimulators, to attain a target joint torque level while minimizing muscle fatigue. We measured ankle torque produced by different pairs of pulse amplitude and pulse duration applied to the plantar-flexors. In each session, we measured the maximum generated torque and calculated muscle fatigue (fatigue time and torque-time integral). Then, we determined the pulse amplitude and pulse duration pair that generated a target level of torque while minimizing muscle fatigue. High bilateral symmetry and day-to-day repeatability was observed for the torque time-series between the left and right plantar-flexors of each participant (median correlation coefficient = 0.95). Compared to the average fatigue obtained by various pulse amplitude and pulse duration pairs for a given level of torque, delivering pulses with the optimal pair reduced fatigue on average by 22.5% according to fatigue time and 6.6% according to torque-time integral. We created an empirical model describing how pulse amplitude and pulse duration can be modulated to generate specific levels of plantar-flexion torque with minimum muscle fatigue.

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“…Func tional electrical stimulation (FES) is a discipline where speci ficity associated with nerve fiber excitation and signal detection is highly desirable. One of the predominant issues related to the field-based approach in FES is the inability to specifically con trol excitation and isolate signal detection at the level of indi vidual nerve fibers [5].…”

Section: Introductionmentioning

confidence: 99%

Strategies for improving neural signal detection using a neural-electronic interface

Szlavik

2003

IEEE Trans. Neural Syst. Rehabil. Eng.

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Abstract-There have been various theoretical and experi mental studies presented in the literature that focus on interfacing neurons with discrete electronic devices, such as transistors. From both a theoretical and experimental perspective, these studies have emphasized the variability in the characteristics of the detected action potential from the nerve cell. The demonstrated lack of reproducible fidelity of the nerve cell action potential at the device junction would make it impractical to implement these devices in any neural prosthetic application where reliable detection of the action potential was a prerequisite. In this study, the effects of several different physical parameters on the fidelity of the de tected action potential at the device junction are investigated and discussed. The impact of variations in the extracellular resistivity, which directly affects the junction seal resistance, is studied along with the impact of variable nerve cell membrane capacitance and variations in the injected charge. These parameters are discussed in the context of their suitability to design manipulation for the purpose of improving the fidelity of the detected neural action potential. In addition to investigating the effects of variations in these parameters, the applicability of the linear equivalent circuit approach to calculating the junction potential is investigated.Index Terms-Nervous system, neural systems, neural elec tronics, neuron transistor interfacing, neuron transistor.

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The effect of stimulus current pulse width on nerve fiber size recruitment patterns

Cited by 36 publications

References 17 publications

Imaging Neurovascular Function and Functional Recovery after Stroke in the Rat Striatum Using Forepaw Stimulation

Imaging Neurovascular Function and Functional Recovery after Stroke in the Rat Striatum Using Forepaw Stimulation

Minimizing muscle fatigue through optimization of electrical stimulation parameters

Strategies for improving neural signal detection using a neural-electronic interface

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