Electrode Surgical Implantation Protocol

©Open Source Instruments Inc.
Generated from protocols provided by Luiz De Silva, PhD, UCL and Rob Wykes, PhD, UCL.
For use with OSI telemetry devices and Telemetry System Electrode Implantation Protocol. What is the procedure for recording EMG? How do I implant depth electrodes? Surface electrodes with set screws.


Contents

Introduction
Related Protocols
Depth Electrodes
J-ElectrodeR-Electrode
W-ElectrodeX-Electrode
Coiled Wire Electrode
EMG Electrode Implantation Protocol
IntroductionMaterials
1. Device Preparation2. Head Incision and Exposure
3. Device Implantation4. Neck Muscle Incision
5. Electrode Insertion6. Securing the Wire
7. Closing
Notes and Best Practices

Introduction

Disclaimer: These protocols are designed to act as a guide as you become familiar with the device and system. Surgical and animal welfare guidelines vary from institution to institution. Please consult your institution's veterinary professional to ensure you are in accordance with local guidelines and protocols.

Note: This procedure will specifically detail the surgical procedure for implanting electrodes for EEG and electromyography (EMG) recordings in mice and rats using either our SCT or HMT device. This protocol will not encompass the entire surgical procedure for our transmitters.

Depth Electrodes

J-Electrode

Materials Required

Directions

R-Electrode

Materials Required

Directions

  1. The R-electrode is equipped with both a canula for injections and a depth electrode wrire. Make sure the burrhole you drill is big enough for both the cannula and the wire to be implanted.
  2. Cut the insulated electrode wire back to your desired length, depending on the depth you would like to record from. Some of our customers like to cut the electrode at an angle, create a sharper tip that allows for better penetration of the brain.
  3. Secure your R-electrode by its cannula guide in a clamp, to prevent movement, above animals head. The clamp should be attached to an apparatus that can lower the electrode into the brain steadily, like a stereotaxic instrument.
  4. Use tweezers to take the D-pin connected to your lead and insert it into the E-socket on the R-electrode. If the orientation of the socket does not work for your surgery, let use know and we can specialize the orientation for your next order.
  5. Confirm a strong connection between the lead and the electrode by grabbing the lead near the socket-pin connection and gently tugging.
  6. Lower the electrode and cannula into the burrhole.
  7. Put the dummy cap on the R-electrode.

W-Electrode

Materials Required

Directions

  1. Cut the insulated electrode wire back to your desired length, depending on the depth you would like to record from. Some of our customers like to cut the electrode at an angle, creater a sharper tip that allows for better penetration of the brain.
  2. The W-electrode has a post that needs to be cut back above the socket and pin connection, after implantation and cementing. The post can be hard to cut, so we advice practicing this cut before the surgery, to make sure you use the best clippers and cutting method to reduce the shaking that can occur during the snip.
  3. Secure your W-electrode by its cannula guide in a clamp, to prevent movement, above animals head. The clamp should be attached to an apparatus that can lower the electrode into the brain steadily, like a stereotaxic instrument.
  4. Use tweezers to take the D-pin connected to your lead and insert it into the E-socket on the W-electrode.
  5. Gently pull on the lead to make sure the crimp contact is secure. It should not be a lose connection.
  6. Lower the electrode into the burrhole to your desired depth, using your stereotaxic apparatus
  7. Once in place, carefully cut the metal post at the thinned secton right above the socket.
  8. Cover depth electrodes with dental cement.

X-Electrode

Materials Required

Directions

  1. Cut the insulated thin electrode wire back to your desired length, depending on the depth you would like to record from. Some of our customers prefer to cut teh electrode at an angle, to allow for better penetration into the brain.
  2. The X-electrode has a post that needs to be cut back above the socket and pin connection, after implantation and cementing. The post can be hard to cut, so we advice practicing this cut before the surgery, to make sure you use the best clippers and cuttng method to reduce the shaking that can occur during the snip.
  3. Secure your X-electrode by its cannula guide in a clamp, to prevent movement, above animals head. THe clamp should be attached to an apparatus that can lower the electrode into the brain steadily, like a stereotaxic instrument.
  4. If your B-lead is not stripped to expose the stainless steel coil at the end, do so now. You want 1.5-3mm of coil exposed at the end. We have found the process to be easier with closer to 3mm of exposed coil. See the Lead Stripping section for information on how to do this.
  5. Hold the B-lead with the tweezers or your fingers, about 5mm away from the exposed coil. Place the Q-ferrule on the exposed end of the B-lead. It is very easy for the Q-ferrule to fall if the lead, so move slowly and put the ferrule on the lead when in close proximity to your X-electrode.
  6. Next, you will notice there is about 4mm of wire protruding from the side of the X-electrode, this is where you will make the crimp connection. Make sure that a few mm of this protruding wire is striped of its teflon insulation before crimping.
  7. Gently guide the coiled wire with Q-ferrule over the protruding X-electrode wire. You want the X-electrode wire to go through the center of the coil.
  8. Once the coil+ferrule are over the X-electrode wire, position the Q-ferrule so that it is covering both the coiled wire and the stripped portion of the X-electrode wire
  9. Use your crimping tool and place it over the ferrule and crimp hard. The Q-ferrule should collapse over the coil and stripped wire, securing them in place.
  10. Gently pull on the lead to make sure the crimp contact is secure
  11. Cover the electrodes in dental cement, option to apply a little bit of vetbond first
  12. Snip back the X-electode post at the thinned section, cover any remaining exposed metal with more dental cement

Coiled Wire Electrode

Materials Required

  • Lead with coiled wire
  • Set screws
  • Screw driver
  • Cyanoacrylate
  • Dental cement

    • Directions

    1. Strip the silicone off of the end of the lead to expose 1-2mm of bare coiled wire. See our video tutorial for guidance
    2. Use tweezers to gently striaghten the bare coiled wire, be careful not to stretch out the silicone coated portion of the wire. Make a 90 degree bend in the wire where the silicone coating ends.
    3. Cut straighted wire electrode to desired length.
    4. After you make your burrholes in the animal skull, take your screws and test that they fit snuggly into the holes. If they fit, remove them.
    5. Next, you will implant or mount your transmitter. If you are using an SCT, implant the transmitter in the animals back and feed the leads up and through the incision in the head. If you are using an HMT, first cement the EIF to the skull of the animal before implanting the electrodes.
    6. Now you are ready to implant the electrodes. Take the bent wire and insert it into the hole until it reaches your desired depth. While holding the wire in place, carefully screw in the set screw until it is secured the wire.
    7. Repeat with all burr holes and wired electrodes
    8. Apply a thin layer of cyanoacrylate over the skull to secure the wire further.
    9. Cover all burr holes and screws with dental cement. The dental cement acts as an insulation and reduces the appearance of artifact in your EEG signal.

    EMG Electrode Implantation Protocol

    Materials

    1. Device Preparation

    1. Ensure you have a lead with 3-4mm of exposed coil wire termination, attached to EIF/HMT or SCT. You can strip extra silicone off of the lead if needed, just follow our strip
    2. Confirm your expose coil wire fits through your syringe needle.
    3. Sterilize all tools and materials prior to use.
    4. Calibrate and check stereotaxic apparatus.

    2. Head Incision and Exposure

    1. Using forceps and scissors, lift the scalp and remove a patch of skin to expose the top of the skull.
    2. Unlike when we are only implanting electrodes in the brain of the animal for EEG, with this EMG protocol we will need to extend the head incision a few millimeters past the skull to expose the animals trapezius muscles. Do not create a second incision for the trapezius muscles, simply use your scissors to length the existing head incision.
    3. Make sure both trapezius muscles of the neck are exposed, as you will implant throught both.
    4. Continue following the SCT and HMT surgical protocols to approrptiately clean and prepare the exposed areas.

    3. Device Implantation

    1. If using SCT: follow our SCT protocol to implant the transmitter and pull the leads up and through the neck incision before implanting the EMG electrode. Make sure to follow the SCT surgical protocol in its entirety to ensure implanataion, closing, and animal monitoring is accurate.
    2. If using HMT: follow our HMT protocol to attach the EIF connector to the scalp of the animal and prepare any EEG electrode burrholes before implanting the EMG electrode. Make sure to follow the HMT surgical protocol in its entirety to ensure implanataion, closing, and animal monitoring is accurate.

    4. Neck Muscle Incision

    1. Find the top of the trapezius muscles on the mouses neck, at the base of the skull, and identify the midline between the two muscles.
    2. Using a syringue needle with a pointed tip, create a horizontal tunnel of about ~2mm length through the the center of the neck muscles. The syringe should exit the muscle on the otherside. Use cotton to control any bleeding.
    3. Leave the syringe needle in the muscle

    5. Electrode Insertion

    1. With the syringe needle still in the muscle, take your stripped coiled wire (ie. an A-coil lead termination) and insert it through the syringue needle, from the base of the needle where the syringue connection is. Thread the coiled wire all the way through the needle until it exits the muscle on the other end.

    6. Securing the Wire

    1. Make sure 1-2mm of the end of the bare wire comes out of the muscle before you remove the syringe.
    2. Pull the syringe out gently while holding the wire in place.
    3. Use the OSI provided wire cap and cap the end of the wire where it exits the muscle using tweezers.
    4. Optional: Use fast drying silicone epoxy (Kwik Cast) to secure the cap onto the wire. Take care to not let the epoxy drip into the tunnel in the muscle.
    5. Suture into the muscle and over the capped wire using a few stiches. The sutures will also help keep the cap in place securely on the wire.
    6. Suture the subcutaneous lead at the entrance of the tunnel you made in the muscle to prevent movement from either end of the implanted wire.
    7. Optional: Apply a small amount of dental cemenet to first half part of the lead (before it enters the muscle) to prevent it moving too much under the skin of the animal. If ypu put too much dental cement on it may restrict the animals neck mobility.

    7. Closing

    1. Follow the SCT and HMT Surgical protocols for full closing steps.
    2. Ensure the electrode is secure and all applied substances are fully dried and cured.
    3. Make sure there some excess length in the EMG lead, to prevent tugging when the animal moves its head and neck after recovery
    4. To close the incision above the EMG electrode, suture the skin back together until you reach the base of the skull.
    5. Continue with dental cement cap procedure as meantioned in SCT and HMT Surgical protocols. See those SCT and HMT protocols for full closing steps.

    Notes and Best Practices