Strength–duration relationship for intra- versus extracellular stimulation with microelectrodes

Rattay, Frank; Paredes, Liliana; Leão, Richardson N.

doi:10.1016/j.neuroscience.2012.04.004

Cited by 65 publications

(71 citation statements)

References 56 publications

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“…This is consistent with predictions from computational modelling [30], [31] and with previous studies involving epiretinal electrical stimulation of retinal ganglion cells in other species (e.g. rat, guinea pig and monkey retinae: [32], rabbit retina: [33]).…”

Section: ) Waveform Parameterssupporting

confidence: 92%

Optimizing the Electrical Stimulation of Retinal Ganglion Cells

Hadjinicolaou

Savage

Apollo

et al. 2015

IEEE Trans. Neural Syst. Rehabil. Eng.

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Epiretinal prostheses aim to restore visual perception in the blind through electrical stimulation of surviving retinal ganglion cells (RGCs). While the effects of several waveform parameters (e.g., phase duration) on stimulation efficacy have been described, their relative influence remains unclear. Further, morphological differences between RGC classes represent a key source of variability that has not been accounted for in previous studies. Here we investigate the effect of electrical stimulus waveform parameters on activation of an anatomically homogenous RGC population and describe a technique for identifying optimal stimulus parameters to minimize the required stimulus charge. Responses of rat A2-type RGCs to a broad array of biphasic stimulation parameters, delivered via an epiretinal stimulating electrode (200 × 200 μ m) were recorded using whole-cell current clamp techniques. The data demonstrate that for rectangular charge-balanced stimuli, phase duration and polarity have the largest effect on threshold current amplitude-cells were most responsive to cathodic-first pulses of short phase duration. Waveform asymmetry and increases in interphase interval further reduced thresholds. Using optimal waveform parameters, we observed a drop in stimulus efficacy with increasing stimulation frequency. This was more pronounced for large cells. Our results demonstrate that careful choice of electrical waveform parameters can significantly improve the efficacy of electrical stimulation and the efficacy of implantable neurostimulators for the retina.

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Section: ) Waveform Parameterssupporting

confidence: 92%

Optimizing the Electrical Stimulation of Retinal Ganglion Cells

Hadjinicolaou

Savage

Apollo

et al. 2015

IEEE Trans. Neural Syst. Rehabil. Eng.

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“…Studies in the central nervous system (CNS) reported that sodium channels of the type Nav1.6 which are located in the band region have lower thresholds than Nav1.2 type channels that are located in somatic and dendritic parts, respectively (Hu et al (2009)). For stimulation in the CNS using micro electrodes close to the soma or even further away from the actual band region this means that the AIS is likely to be the site of spike initiation (Rattay and Wenger (2010); Rattay et al (2012)). We do not know yet if this special sodium channel distribution also can be of relevance in the stimulation of retinal ganglion cells.…”

Section: Discussionmentioning

confidence: 99%

Influence of the sodium channel band on retinal ganglion cell excitation during electric stimulation – A modeling study

Werginz¹,

Fried²,

Rattay³

2014

Neuroscience

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Electric stimulation using retinal implants allows blind people to re-experience a rudimentary kind of vision. The elicited percepts or so called ’phosphenes’ are highly inconstant and therefore do not restore vision properly. The better knowledge of how retinal neurons, especially retinal ganglion cells, respond to electric stimulation will help to develop more sophisticated stimulation strategies. Special anatomic and physiologic properties like a band of highly dense sodium channels in retinal ganglion cells may help to achieve a focal activation of target cells and as a result better restoration of vision. A portion of retinal ganglion cell axons, about 40 μm from the soma and between 25 and 40μm in length, shows a specific biophysical property. Electrode locations close to a band of highly dense sodium channels which was identified immunochemically show lowest thresholds during electric stimulation. The (modeled) thresholds for this kind of structure result in lowest thresholds as well. The influence on the location where action potentials are generated within the axon is far reaching. When a stimulating electrode is positioned far outside the actual band region the site of spike initiation still remains within the sodium channel band. These findings suggest to further examine the key mechanisms of activation for retinal ganglion cells because focal activation without influencing passing axons of neurons located far away can improve the outcome of electric stimulation and therefore the development of retinal implants.

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“…The curvature of the strength–duration function depends on the TMS pulse shape and the membrane dynamics of the neurons directly depolarized by the TMS electric field (Rattay et al, 2012). To parameterize the strength–duration curve, the neural membrane can be approximated as a low-pass filter with time constant τ m (Barker et al, 1991; Corthout et al, 2001; Lapicque, 1907).…”

Section: Methodsmentioning

confidence: 99%

Pulse width dependence of motor threshold and input–output curve characterized with controllable pulse parameter transcranial magnetic stimulation

Peterchev

Goetz

Westin

et al. 2013

Clinical Neurophysiology

128

185

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Objective To demonstrate the use of a novel controllable pulse parameter TMS (cTMS) device to characterize human corticospinal tract physiology. Methods Motor threshold and input-output (IO) curve of right first dorsal interosseus were determined in 26 and 12 healthy volunteers, respectively, at pulse widths of 30, 60, and 120 μs using a custom-built cTMS device. Strength–duration curve rheobase and time constant were estimated from the motor thresholds. IO slope was estimated from sigmoid functions fitted to the IO data. Results All procedures were well tolerated with no seizures or other serious adverse events. Increasing pulse width decreased the motor threshold and increased the pulse energy and IO slope. The average strength–duration curve time constant is estimated to be 196 μs, 95% CI [181 μs, 210 μs]. IO slope is inversely correlated with motor threshold both across and within pulse width. A simple quantitative model explains these dependencies. Conclusions Our strength–duration time constant estimate compares well to published values and may be more accurate given increased sample size and enhanced methodology. Multiplying the IO slope by the motor threshold may provide a sensitive measure of individual differences in corticospinal tract physiology. Significance Pulse parameter control offered by cTMS provides enhanced flexibility that can contribute novel insights in TMS studies.

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Strength–duration relationship for intra- versus extracellular stimulation with microelectrodes

Abstract: Highlights► The excitability time constant chronaxie for electrical stimulation is analyzed. ► Chronaxie varies along the neural axis. ► Extracellular stimulation with microelectrodes causes short chronaxies. ► In some cases strength–duration curves have a bimodal shape.

Cited by 65 publications

References 56 publications

Optimizing the Electrical Stimulation of Retinal Ganglion Cells

Optimizing the Electrical Stimulation of Retinal Ganglion Cells

Influence of the sodium channel band on retinal ganglion cell excitation during electric stimulation – A modeling study

Pulse width dependence of motor threshold and input–output curve characterized with controllable pulse parameter transcranial magnetic stimulation

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