Electrically Evoked Compound Action Potentials in Spinal Cord Stimulation: Implications for Preclinical Research Models

Aim: To validate the use of motor activation thresholds (MoT) to titrate stimulation amplitudes for spinal cord stimulation in rodent models. Methods: We recorded thresholds for MoT and sciatic compound action potentials in ten Sprague-Dawley rats implanted with epidural electrodes. Strength duration curves were fitted to the threshold values. Results: Activation thresholds were in the same order for both MoT and sciatic compound action potentials. Conclusion: Many of the large, myelinated fibers traversing the dorsal columns in the rodent spine are activated at similar current levels to MoT. Epidural stimulation in rodents needs to be applied at amplitudes close to MoT to activate these axons.

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Evoked Compound Action Potentials Reveal Spinal Cord Dorsal Column Neuroanatomy

Neuromodulation Technology at the Neural Interface ◽

10.1111/ner.12968 ◽

2019 ◽

Vol 23 (1) ◽

pp. 82-95 ◽

Cited By ~ 3

Author(s):

John L. Parker ◽

Milan Obradovic ◽

Nastaran Hesam Shariati ◽

Robert B. Gorman ◽

Dean M. Karantonis ◽

...

Keyword(s):

Spinal Cord ◽

Action Potentials ◽

Dorsal Column ◽

Compound Action Potentials ◽

Spinal Cord Dorsal ◽

Compound Action

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Modular double sucrose gap apparatus for improved recording of compound action potentials from rat and mouse spinal cord white matter preparations

Journal of Neuroscience Methods ◽

10.1016/j.jneumeth.2009.12.006 ◽

2010 ◽

Vol 187 (1) ◽

pp. 33-40 ◽

Cited By ~ 12

Author(s):

Alexander A. Velumian ◽

Yudi Wan ◽

Marina Samoilova ◽

Michael G. Fehlings

Keyword(s):

Spinal Cord ◽

White Matter ◽

Action Potentials ◽

Mouse Spinal Cord ◽

Modular Double ◽

Compound Action Potentials ◽

Sucrose Gap ◽

Compound Action

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Contribution of Fast and Slow Conducting Myelinated Axons to Single-Peak Compound Action Potentials in Rat Spinal Cord White Matter Preparations

Journal of Neurophysiology ◽

10.1152/jn.00435.2010 ◽

2011 ◽

Vol 105 (2) ◽

pp. 929-941 ◽

Cited By ~ 9

Author(s):

Alexander A. Velumian ◽

Yudi Wan ◽

Marina Samoilova ◽

Michael G. Fehlings

Keyword(s):

Spinal Cord ◽

White Matter ◽

Action Potentials ◽

Lower Threshold ◽

Differential Sensitivity ◽

Single Peak ◽

Rat Spinal Cord ◽

Conducting Component ◽

Compound Action Potentials ◽

Compound Action

Unlike recordings derived from optic nerve or corpus callosum, compound action potentials (CAPs) recorded from rodent spinal cord white matter (WM) have a characteristic single-peak shape despite the heterogeneity of axonal populations. Using a double sucrose gap technique, we analyzed the CAPs recorded from dorsal, lateral, and ventral WM from mature rat spinal cord. The CAP decay was significantly prolonged with increasing stimulus intensities suggesting a recruitment of higher threshold, slower conducting axons. At 3.5 mm conduction distance, a hidden higher threshold, slower conducting component responsible for prolongation of CAP decay was uncovered in 22 of 25 of dorsal WM strips by analyzing the stimulus-response relationships and a normalization-subtraction procedure. This component had a peak conduction velocity (CV) of 5.0 ± 0.2 (SE) m/s as compared with 9.3 ± 0.5 m/s for the lower threshold peak ( P < 0.0001). Oxygen-glucose deprivation (OGD), along with its known effects on CAP amplitude, significantly ( P < 0.015) shortened the CAP decay. The hidden higher threshold, slower conducting component showed greater sensitivity to OGD compared with the lower threshold, faster conducting component, suggesting a differential sensitivity of axonal populations of spinal cord WM. At longer conduction distances and lower temperatures (9.8 mm, 22–24°C), the slower peak could be directly visualized in CAPs at higher stimulation intensities. A detailed analysis of single-peak CAPs to identify their fast and slow conducting components may be of particular importance for studies of axonal physiology and pathophysiology in small animals where the conduction distance is not sufficiently long to separate the CAP peaks.

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Electrically Evoked Compound Action Potentials Recorded From the Sheep Spinal Cord

Neuromodulation Technology at the Neural Interface ◽

10.1111/ner.12053 ◽

2013 ◽

Vol 16 (4) ◽

pp. 295-303 ◽

Cited By ~ 22

Author(s):

John L. Parker ◽

Dean M. Karantonis ◽

Peter S. Single ◽

Milan Obradovic ◽

James Laird ◽

...

Keyword(s):

Spinal Cord ◽

Action Potentials ◽

Compound Action Potentials ◽

Compound Action

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Reflexes, fictive respiration and cell division in the brain and spinal cord of the newborn opossum, Monodelphis domestica, isolated and maintained in vitro

Journal of Experimental Biology ◽

10.1242/jeb.152.1.1 ◽

1990 ◽

Vol 152 (1) ◽

pp. 1-15

Author(s):

J. G. Nicholls ◽

R. R. Stewart ◽

S. D. Erulkar ◽

N. R. Saunders

Keyword(s):

Spinal Cord ◽

Electrical Activity ◽

Action Potentials ◽

Monodelphis Domestica ◽

Spinal Reflexes ◽

Bathing Solution ◽

Proliferative Zone ◽

Compound Action Potentials ◽

Compound Action

1. The entire central nervous system (CNS) was isolated from 1- to 4-day-old newborn South American opossums (Monodelphis domestica). At this stage the CNS has only an embryonic forebrain (two-layered) and no cerebellum and corresponds to a 14-day rat embryo. Its eyes, ears and hind-limbs are only at an early stage of formation. The isolated CNS preparations continue to develop and to produce electrical signals for up to 4 days in oxygenated Krebs' fluid at 23 degrees C. 2. The longitudinal axis of the CNS showed markedly different stages of development. More neuroblast cells were present in the proliferative zone in lumbosacral than in cervical or thoracic regions of the cord. 3. The progeny of dividing cells were labelled in isolated preparations by applying bromodeoxyuridine (BrdU) to the bathing solution for 2 h. Stained precursor cells were observed in CNS that had been left in Krebs' fluid for 4 days before applying BrdU and also in CNS that had been exposed to BrdU shortly after dissection and then left for 4 days. 4. Compound action potentials were evoked from the isolated CNS by stimulation with extracellular electrodes. Compound action potentials increased in amplitude with stronger stimulation and showed discrete peaks of conduction velocity. All electrical activity was eliminated reversibly by 0.1 mumol l-1 tetrodotoxin applied to the bathing solution. Block and recovery occurred with a half-time of approximately 5 min. High concentrations of magnesium (20 mmol l-1) reversibly blocked slower components of the volley. 5. Reflexes in cervical and thoracic segments of the spinal cord continued to function in isolated preparations. Stimulation of a dorsal root evoked bursts of impulses in the appropriate ventral root. Spontaneous and evoked activity in ventral roots was eliminated reversibly by 20 mmol l-1 magnesium. 6. In thoracic segments, spontaneous rhythmical bursts of action potentials were recorded. Burst activity was correlated with respiratory movements of the ribs in semi-intact preparations in which a few ribs and muscles were left attached to the isolated CNS. 7. At raised temperatures of 28 degrees C compared to 23 degrees C both spontaneous and evoked electrical activity were reversibly reduced. 8. Together these results show that the isolated CNS of the newborn opossum survives well in culture. The preparation offers advantages for pharmacological and physiological studies of spinal reflexes, for analysis of the mechanisms underlying rhythmical respiratory activity and for following the time course of CNS development in vitro.

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