Electrode Surgery Protocols, EEG and EMG

©2025, Alice Hashemi Open Source Instruments Inc.
Disclaimer: This is a draft protocol, as the full procedure has not yet been tested with our system. The portion of the protocol covering implantation of EEG electrodes has been verified. However, the EMG electrode implantation method-specifically for placement in the neck-has not yet been validated with our system.
Acknowledgement: Generated from protocols provided by Luiz De Silva, PhD, UCL and Rob Wykes, PhD, UCL. EMG electrode implantation technique provided by Joel Raymond, PhD, Postdoctoral Research Fellow, Rutgers University.

Contents

Introduction
Related Protocols
Depth Electrodes
J-ElectrodeR-Electrode
W-ElectrodeX-Electrode
Surface Electrodes
Coiled WireStraightened Wire
Screw Electrodes
EMG Electrode Implantation Protocol
Materials1. Device Preparation
2. Head Incision and Exposure3. Transmitter Device Implantation
8. EMG Electrode Placement9. Securing the EMG Electrodes
7. ClosingNotes and Best Practices

Introduction

Disclaimer: These protocols are intended as a guide for familiarization with the device and system. Surgical and animal welfare guidelines vary by institution. Please consult your institution's veterinary professional to ensure compliance with local regulations and protocols.

Purpose: This procedure specifically details the surgical implantation of electrodes for EEG and EMG recordings in mice and rats using either our SCT or HMT devices. This protocol does not cover the complete surgical procedure for transmitter implantation. page-chunk match-prompts-only Electrode implantation for EMG and EEG What is the procedure for implantaing eletrodes in an animal? Surgical protocol for depth electrode implantation?

Depth Electrodes

Our Depth Electrodes allow for a deeper reach into the brain. The insulated wire in the electrode will bve delivered either in the standard length or in a length specified by the you. You can cute the wire back to any length yourseld, either with a square cut or at an angle for better penetration. Each electrode provides a mounting fixture by which we can hold the electrode during surgery.

J-Electrode

Figure: J-Electrode

Materials Required

Directions

R-Electrode

Figure: R-Electrode
Note: The R-Electrode is designed to allow repetead substance into the animals brain. The guide cannula remains on the animals head throughout the experiment.

Materials Required

Directions

  1. The R-Electrode includes both a cannula for injections and a depth electrode wire. Drill a burr hole large enough for both components.
  2. Trim the insulated electrode wire to the desired length. Optionally, cut at an angle for easier penetration.
  3. Secure the R-Electrode by its cannula guide in a stereotaxic clamp above the animal's head.
  4. Connect the D-Pin lead to the E-Socket using tweezers. Customized orientations are available upon request.
  5. Check the connection by gently tugging near the socket-pin junction.
  6. Lower the electrode and cannula into the burr hole.
  7. Cover the base of the electrode and the burr hole with dental cement.
  8. Attach the dummy cap to the R-Electrode when not injecting.

W-Electrode

Figure: W-Electrode

Materials Required

Directions

  1. Trim the insulated electrode wire to the target length. Optionally, cut the tip at an angle for easier penetration.
  2. Note: The W-Electrode has a post that must be cut above the socket and pin connection after implantation. Practice beforehand to reduce shaking.
  3. Secure the W-Electrode by its cannula guide in a stereotaxic clamp above the head.
  4. Insert the D-Pin lead into the E-Socket on the W-Electrode.
  5. Confirm the crimp contact is secure by gently pulling the lead.
  6. Lower the electrode into the burr hole to the desired depth.
  7. Cut the metal post carefully at the thinned section above the socket.
  8. Cover the electrode and socket area with dental cement.

X-Electrode

Figure: X-Electrode

Materials Required

Directions

  1. Trim the insulated electrode wire to the target length. Optionally, cut the tip at an angle for penetration.
  2. The X-Electrode has a post that must be cut after implantation. Practice the cut beforehand to avoid shaking.
  3. Secure the X-Electrode in a stereotaxic clamp above the head.
  4. If the B-lead is unstripped, expose 1.5-3 mm of coil at the tip (3 mm preferred). See Lead Stripping for guidance.
  5. Hold the B-lead ~5 mm from the coil and slide the Q-ferrule on, keeping it near the X-Electrode.
  6. Ensure ~4 mm of stripped X-Electrode wire is available for the crimp.
  7. Guide the coil and Q-ferrule over the X-Electrode wire so the wire passes through the coil center.
  8. Position the ferrule to overlap both coil and stripped wire.
    9. Video: X-Electrode and B-Lead Crimp Connection with Q-Ferrule.
  9. Crimp firmly with pliers to secure.
  10. Test the crimp by gently pulling the lead.
  11. Cover the electrode and socket with dental cement (optionally add Vetbond adhesive first).
  12. Cut the X-Electrode post at the thinned section and seal any exposed metal with cement.

Surface Electrodes

Figure: Angled Wire Electrode, held in place by a fastening screw.

Coiled Wire

Note: Coiled wire electrode use a helical bare wire tip. Straighten them prior to implantation.
Figure: A-Coil wire termination at the end of a B-Lead

Materials

Directions

  1. Straighten the bare coiled wire carefully with tweezers, avoiding tension on the lead.
  2. Create a 90 degree bend at the midpoint of the bare wire.
  3. Trim the bent section so it matches skull thickness plus desired cortical depth.
  4. Test screw fit in burr holes; holes should be slightly smaller for a snug fit.
  5. Insert the electrode into the burr hole, securing it with tweezers.
  6. Leave a short section of exposed wire atop the skull (before the bend) to prevent screw contact with insulation.
  7. Optionally apply semi-cured Vetbond to the wire on the skull (avoid the burr hole) to stabilize before screwing.
  8. Insert the screw into the burr hole, ensuring the electrode does not bind in the threads.
  9. Cover the screw and exposed wire with dental cement to insulate and reduce EEG artifacts.

Notes

Straightened Wire

Figure: M-Wire termination at the end of a B-Lead

Materials

Directions

  1. Create a 90 degree bend halfway along the bare wire.
  2. Trim the bent section to match skull thickness plus target depth.
  3. Test screw fit in burr holes for snug engagement.
  4. Insert the electrode into the burr hole while securing with tweezers.
  5. Leave a small section of exposed wire atop the skull to isolate from the screw.
  6. Optionally apply semi-cured Vetbond on the skull surface for stability, avoiding the burr hole.
  7. Screw into the burr hole without trapping the electrode in threads.
  8. Seal with dental cement to insulate and reduce artifacts.

Screw Electrodes

Figure: Screw Electrodes. Left: K-Screw. Right: B-Screw.

Materials

Directions

  1. Verify screw fit in burr holes for a tight hold.
  2. Screw the electrode into the burr hole, ensuring the wire remains free of threads.
  3. Cover the screw and exposed wire with dental cement to insulate and minimize signal artifacts.

EMG Electrode Implantation Protocol

Materials

1. Device Preparation

  1. Confirm the EMG leads (connected to the SCT or HMT) have 3-4 mm of exposed coiled wire. Strip additional silicone if necessary (lead stripping video).
  2. Verify the exposed coils fit through the selected syringe needles.
  3. Sterilize all tools and materials before use.

2. Head Incision and Exposure

  1. Use forceps and scissors to lift the scalp and remove a section to expose the skull.
  2. For EMG, extend the head incision slightly beyond the skull to expose trapezius muscles, do not make a separate incision.
  3. Expose both trapezius muscles for electrode placement.
  4. Remove connective tissue from the skull and clean with diluted (6% v/v) hydrogen peroxide, then dry immediately. Remove residual tissue with a bone scraper.

3. Transmitter Device Implantation

  1. For SCT: Follow the SCT Surgical Protocol to implant the transmitter and tunnel the leads before EMG placement. Ensure the EMG lead is pre-cut, stripped, and has adequate slack.
  2. For HMT: Follow the HMT Surgical Protocol to attach the EIF connector and prepare EEG burr holes. Ensure the EMG lead is longer than EEG leads so it can reach the muscle in the neck
  3. Refer to the EIF manual to ensure you know the purpose and identity of each lead.

8. EMG Electrode Placement

Figure: SCT Surgical diagram demonstrating the surgical insertion of EMG leads into the neck of a rodent. In this diagram, the syringe needle use to create one of the tunnels in the musle is still in place, with an EMG lead threaded through the needle. Note the direction of the syringe needle in relation to the lead.
  1. Identify the top of the trapezius muscles at the base of the skull and locate the midline between them.
  2. You will implant to EMG electrode into the neck. The green and yellow leads. The procedure for implanting and securing the EMG electrode is the same for both leads.
  3. Use a pointed syringe needle to two ~2 mm horizontal tunnels through the trapezius muscles, try to go through both muscles. Begin the insertion on the side of the neck opposite the EMG lead, so that the hub (base) of the syringe needle is on the side of the neck furthest from the lead connection on the EIF, also known as the "exit" of the tunnel. This orientation allows you to remove the needle later by gripping the hub while holding the wire in place.
  4. The needle does not need to go more then a few mm deep into the muscle. It must go deep enough that it can not easily be ripped out of the skin. The needle should create a "tunnel", meaning it should have both and entrance and an exit into the muscle.
  5. Control bleeding with sterile cotton if needed.
  6. Leave the needle in place.
  7. With the syringe still in the muscle, insert the stripped coiled wire (e.g., lead with P -Coil terminus) of your EMG lead through end of the needle. Thread the wire through until it exits from the other end of the muscle tunnel, leaving 1-2mm exposed and on top of the muscle.

10. Securing the EMG Electrodes

Figure: SCT Surgical diagram demonstrating the securement of EMG leads inthe neck of a rodent. In this diagram, you can see the electrode caps place on the exposed wire that exits the tunnel through the muscle. The cap is secured either by and additional suture over the cap, or with Kwik Cast (either in the cap or over the cap and lead).
Figure: HMT Surgical diagram demonstrating the surgical insertion of EMG leads into the neck of a rodent. In this diagram, the syringe needle use to create one of the tunnels in the musle is still in place, with an EMG lead threaded through the needle. Note the direction of the syringe needle in relation to the lead.
    1. Ensure 1-2 mm of the bare wire protrudes from the muscle on the exit side before removing the needle.
    2. Carefully remove the needle while keeping the wire in position. It is helpful to have the wire extend past the end of the needle a small amount, so you can grip it with tweezers while removing the needle.
    3. Once the needle is removed, use tweezers to attach the OSI-provided wire cap to the exposed end of the wire at the exit of the tunnel. The wire cap should cover all of the exposed coiled wire that sits on the muscle. The purpose of the cap is to insulate the exposed electrode wire, reducing the risk of artifacts in the EMG signal.
    4. Optional: Use a small amount of Kwik-Cast sealant to secure the cap. Be careful not to allow any sealant to drip into the muscle tunnel.
    5. Place a few sutures over the capped wires, at the exit of the tunnel, to anchor it in the muscle and hold the cap in place on the exposed wire.
    6. Suture the subcutaneous leads at the muscle entry point to prevent movement of the implanted wire.
    7. Optional: Apply a small amount of dental cement to the portion of the lead before it enters the muscle to reduce movement under the skin. Avoid excess cement, which may restrict neck mobility.

    7. Closing

    1. Follow SCT or HMT closing protocols.
    2. Ensure electrodes are secure and adhesives are fully cured.
    3. Leave slack in the EMG lead to accommodate head and neck motion.
    4. Close the incision by suturing up to the skull base.
    5. Complete the dental cement cap procedure as per SCT or HMT protocols.

    Notes and Best Practices