Infrared neural stimulation of human spinal nerve roots<i>in vivo</i>

Cayce, Jonathan M.; Wells, Jonathon; Malphrus, Jonathan D.; Kao, Chris; Thomsen, Sharon; Tulipan, Noel; Konrad, Peter E.; Jansen, E.; Mahadevan‐Jansen, Anita

doi:10.1117/1.nph.2.1.015007

Cited by 45 publications

(63 citation statements)

References 48 publications

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“…Infrared neural modulation (INM) in particular offers both neural stimulation and inhibition without introducing exogenous agents. Infrared neural stimulation (INS) has shown to be an effective method for stimulating action potentials in many animal models [23][24][25][26][27][28][29], and has been applied in human dorsal rootlets [30], but its complementary technique, infrared neural inhibition (INI), has yet to be translated for human use due to the temperature rise required for therapy.…”

Section: Introductionmentioning

confidence: 99%

Identifying the Role of Block Length in Neural Heat Block to Reduce Temperatures During Infrared Neural Inhibition

et al. 2019

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Background and Objectives The objective of this study is to assess the hypothesis that the length of axon heated, defined here as block length (BL), affects the temperature required for thermal inhibition of action potential propagation applied using laser heating. The presence of such a phenomenon has implications for how this technique, called infrared neural inhibition (INI), may be applied in a clinically safe manner since it suggests that temperatures required for therapy may be reduced through the proper spatial application of light. Here, we validate the presence of this phenomenon by assessing how the peak temperatures during INI are reduced when two different BLs are applied using irradiation from either one or two adjacent optical fibers. Study Design/Materials and Methods Assessment of the role of BL was carried out over two phases. First, a computational proof of concept was performed in the neural conduction simulation environment, NEURON, simulating the response of action potentials to increased temperatures applied at different full‐width at half‐maxima (FWHM) along axons. Second, ex vivo validation of these predictions was performed by measuring the radiant exposure, peak temperature rise, and FWHM of heat distributions associated with INI from one or two adjacent optical fibers. Electrophysiological assessment of radiant exposures at inhibition threshold were carried out in ex vivo Aplysia californica (sea slug) pleural abdominal nerves ( n = 6), an invertebrate with unmyelinated axons. Measurement of the maximum temperature rise required for induced heat block was performed in a water bath using a fine wire thermocouple. Finally, magnetic resonance thermometry (MRT) was performed on a nerve immersed in saline to assess the elevated temperature distribution at these radiant exposures. Results Computational modeling in NEURON provided a theoretical proof of concept that the BL is an important factor contributing to the peak temperature required during neural heat block, predicting a 11.7% reduction in temperature rise when the FWHM along an axon is increased by 42.9%. Experimental validation showed that, when using two adjacent fibers instead of one, a 38.5 ± 2.2% (mean ± standard error of the mean) reduction in radiant exposure per pulse per fiber threshold at the fiber output (P = 7.3E−6) is measured, resulting in a reduction in peak temperature rise under each fiber of 23.5 ± 2.1% ( P = 9.3E−5) and 15.0 ± 2.4% ( P = 1.4E−3) and an increase in the FWHM of heating by 37.7 ± 6.4% ( P = 1E−3), 68.4 ± 5.2% ( P = 2.4E−5), and 51.9 ± 9.9% ( P = 1.7E−3) in three MRT slices. Conclusions This study provides the first experimental evidence for a phenomenon during the heat block in which the temperature for inhibition is dependent on the BL. While more work is needed to further reduce the temperature during INI, the results highlight that spatial application of the temperature rise during INI must be considered. Optimized implementation of INI may leverage this cellular response to provide optical modul...

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Section: Introductionmentioning

confidence: 99%

Identifying the Role of Block Length in Neural Heat Block to Reduce Temperatures During Infrared Neural Inhibition

et al. 2019

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“…It seems likely that differences in the biological preparation used, the method used to assay neuronal activation, and the parameters used for laser stimulation have contributed to this debate. Nonetheless, interest remains, as indicated by recent studies examining the applicability of INS for human neuroprostheses [6,7].…”

Section: Introductionmentioning

confidence: 99%

In vitro neuronal depolarization and increased synaptic activity induced by infrared neural stimulation

Entwisle

McMullan

Bokiniec

et al. 2016

Biomed. Opt. Express

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Neuronal responses to infrared neural stimulation (INS) are explored at the single cell level using patch-clamp electrophysiology. We examined membrane and synaptic responses of solitary tract neurons recorded in acute slices prepared from the Sprague-Dawley rat. Neurons were stimulated using a compact 1890 nm waveguide laser with light delivered to a small target area, comparable to the size of a single cell, via a single-mode fiber. We show that infrared radiation increased spontaneous synaptic event frequency, and evoked steady-state currents and neuronal depolarization. The magnitude of the responses was proportional to laser output.

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“…293 Finally, early trials in humans have shown that INS can be used to stimulate human dorsal root ganglia. 294 Although the research surrounding INS is promising, clinical applications of INS would require constant stimulation at 12–15 Hz, placing it above the upper threshold for injury. 295 An alternative to bypass these limitations has been proposed that combines INS with extraneural stimulation via nerve cuff.…”

Section: Future Interfaces: Novel Paradigmsmentioning

confidence: 99%

The Evolution of Neuroprosthetic Interfaces

Adewole¹,

Serruya

Harris

et al. 2016

Crit Rev Biomed Eng

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The ideal neuroprosthetic interface permits high-quality neural recording and stimulation of the nervous system while reliably providing clinical benefits over chronic periods. Although current technologies have made notable strides in this direction, significant improvements must be made to better achieve these design goals and satisfy clinical needs. This article provides an overview of the state of neuroprosthetic interfaces, starting with the design and placement of these interfaces before exploring the stimulation and recording platforms yielded from contemporary research. Finally, we outline emerging research trends in an effort to explore the potential next generation of neuroprosthetic interfaces.

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Infrared neural stimulation of human spinal nerve rootsin vivo

Cited by 45 publications

References 48 publications

Identifying the Role of Block Length in Neural Heat Block to Reduce Temperatures During Infrared Neural Inhibition

Identifying the Role of Block Length in Neural Heat Block to Reduce Temperatures During Infrared Neural Inhibition

In vitro neuronal depolarization and increased synaptic activity induced by infrared neural stimulation

The Evolution of Neuroprosthetic Interfaces

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