Mar 03, 2025

Public workspaceAcute stimulation, EMG, and neural recording from a rat sciatic nerve using a self-sizing and soft closing polymer cuff electrode

DOI
dx.doi.org/10.17504/protocols.io.q26g7m17qgwz/v1
  • 1University of Southern California
Alex Baldwin
Icon indicating open access to content
QR code linking to this content
DOI: dx.doi.org/10.17504/protocols.io.q26g7m17qgwz/v1
External link: https://github.com/CARSSCenter/
Protocol Citation: Sahar Elyahoodayan, Junshi Chen, Quentin Rezard, Max Li, Alex Baldwin, Ellis Meng, Dong Song 2025. Acute stimulation, EMG, and neural recording from a rat sciatic nerve using a self-sizing and soft closing polymer cuff electrode. protocols.io https://dx.doi.org/10.17504/protocols.io.q26g7m17qgwz/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: December 11, 2024
Last Modified: March 03, 2025
Protocol Integer ID: 115055
Keywords: rodent, sciatic nerve, cuff electrode, neuromodulation, neurophysiology, electrophysiology, Parylene C
Funders Acknowledgements:
NIH SPARC
Grant ID: 3U41NS129514-02S1
Abstract
This protocol describes acute experiments for sciatic nerve stimulation with leg electromyography (EMG) and sciatic nerve electroneurography (ENG) in a rodent model. A thin-film polymer cuff is used for stimulation, with a traditional silicone cuff used for ENG and needle electrodes used for EMG. Stimulation at various amplitudes is used to determine activation thresholds for the sciatic nerve, and ENG is used to determine both the fiber activation as well as to isolate stimulation artifacts through measurements before and after nerve ligation.
Materials
Animals
Sprague-Dawley rats, >3 mo age, 300-450 g, either sex

Surgical Preparation
Isoflourane
Oxygen
Heating pad
1× phosphate-buffered saline (PBS)
Surgical gauze
Cotton tips

Electrode Placement
Polymer cuff electrode (custom)
Polymer cuff placement tool (custom)
CorTec AirRay Micro Tunnel (2 contact, 1 mm ID, 6 mm length)
Dantec disposable concentric EMG needle, Natus Medical, 25 mm long, 30G diameter
Saline
Syringe
Tweezers

Stimulation and Recording
Multichannel Systems STG 1002
Molecular Devices Digidata 1322A
A-M Systems Model 1700 amplifier
pClamps9 software
Faraday cage
Alligator clips
Suture
Animals
Animals
This study uses Sprague-Dawley rats older than three months weighing 230-400 g. Animals are housed in 12/12 hr light and dark cycles, with surgeries conducted during the light cycle. All animals are given ad libitum access to food and water.
Surgical preparation
Surgical preparation
To initiate anesthesia, place the rat in a sealed chamber and administer an isoflourane and oxygen mixture until the animal reaches light anesthesia. This usually takes 30-60 seconds under 4.5% isoflourane and oxygen administered at a rate of 500 mL/min. Stop the initial anesthesia when rat exhibits no voluntary activity.
Once light anesthesia is initiated, move the rat to a nose cone. Maintain anesthesia with an inhaled mixture of isoflourane (1-2% for female or 1.5-2.5% for male) and oxygen administered at a rate of 500 mL/min using a Somnoflow electronic vaporizer from Kent Scientific. Maintain body temperature with a warming pad set to 37°C. Anesthesia can be tested using toe-pinch reflexes.
Shave the fur above the right hind leg.
Perform a 3 cm midsagittal incision at the right thigh. Hint: First find the tip of greater trochanter by gently pressing the rat thigh with a finger. Second make a small incision and find the connective tissue. Finally make incision along the connective tissue between muscles.
Identify the junction between muscles and separate using blunt dissection.
Expose the sciatic nerve by removing connective tissue around it. Rinse blood off of the nerve using 1× phosphate-buffered saline (PBS). Ensure the nerve remains hydrated with PBS throughout the surgery.
Polymer cuff, recording cuff, and EMG electrode placement
Polymer cuff, recording cuff, and EMG electrode placement
Place the polymer cuff on the sciatic nerve using the placement tool. Details on the polymer cuff electrode's design and manufacture, as well as the placement tool's computed aided design (CAD) files, can be found here: https://github.com/CARSSCenter.
Polymer cuff electrode with major parts labeled.

Placement tool and stand for the polymer cuff electrode with major parts labeled.

Ensure that the expander and holder on the stand and placement tool, respectively, are correctly aligned.

(left) Properly aligned expander and holder. (right) Misaligned expander and holder.

Fill the placement tool's well with saline.
Using a syringe or tweezers, place several drops of saline on the expander shaft.

(left) Saline drops on the expander shaft of the placement tool. (right) Use of a syringe to apply drops of saline to expander shaft.

When placing the cuff, handle the cuff by the silicone lead region and orient the cuff so it is on the left side of the cable. In this orientation, the cuff opening will face downward.

Cuff in correct alignment with the placement tool.

Using tweezers, and handling only the tabs on the cuff, slide the polymer cuff over the expander shaft and then onto the holder of the tool.

Sequence of images showing proper loading of the cuff onto the holder of the placement tool.

Secure the silicone peg holes on the tool's pegs.

Cuff secured to placement tool via pegs.

Remove the placement tool from the stand.

Cuff correctly mounted to placement tool.

Place the tool parallel to the sciatic nerve. While gently holding the tab of the polymer cuff with tweezers, slide the cuff off of the placement tool and onto the sciatic nerve.
The recording electrode is a CorTec AirRay Micro Tunnel silicone cuff with two contacts, an inner diameter of 1 mm and a length of 6 mm. Using two forceps, unwrap the recording cuff, ensuring no contact with metal to prevent electrode damage or continuity disruption. Guide one side of the electrode beneath and around the nerve. Once released, the cuff will naturally wrap around the nerve. Adjust its position to maintain approximately 5 mm of distance from the polymer stimulation cuff.
Insert two needle electrodes in the digitorum longus muscle of the rat's right hind leg for bipolar EMG recording. Each needle consisted of a Dantec Disposable Concentric EMG needle from Natus Medical measuring 25 mm in length and 30G in diameter.
Placement of two cuffs on sciatic nerve and EMG needle in digitorum longus muscle in rat right hind leg.

Stimulation and recording
Stimulation and recording
Ensure that the rat is in a grounded Faraday cage.
Apply stimulation using a Multichannel Systems STG 1002 device. Stimulation consisted of 200 μs pulses, 100 μs interpulse interval, with amplitudes ranging from 100 μA to 1 mA in step sizes of 100 μA. Stimulation was applied at either 1 Hz or 30 Hz.
Record EMG and neural signals using a Molecular Devices Digidata 1322A signal acquisition system and process using pClamps9 software at 100 kHz sampling frequency. For neural signal recording, signals are first passed through a differential AC amplifier by A-M Systems (Model 1700) set to low frequency cutoff 1 Hz, high frequency cutoff 10 kHz, and gain ×1000.
Ligate the sciatic nerve distal to the recording cuff by tightly tying a suture around the nerve. Perform stimulation, neural recording, and EMG recording according to the previous step to confirm EMG activation via sciatic nerve stimulation and that recorded activity is not part of the stimulation artifact.