Spinal Cord Electrophysiology II: Extracellular Suction Electrode Fabrication
February 20th, 2011
A demonstration of the fabrication and use of an extracellular suction electrode used to measure electrophysiological recordings of neonatal rodent spinal cords in vitro
Hi.My name is Resh Gary Dory, and I'm a research assistant in the faf Lab of the Salk Institute for Biological Studies. Today I'll be showing you how to fabricate extracellular suction electrodes using two methods. These electrodes can be used to take electrophysiological recordings of my spinal cords in vitro.
Use an alcohol lamp as a heat source to melt the PE 90 plastic tubing into the desired width. Hold the tubing over the lit flame and remove as it begins to melt, gently pull the ends apart, being careful not to break the middle. This process is shown again.
Remove the tubing as it softens and melts and gently pull the ends apart. Cut the tubing with a sharp razor blade at a point corresponding to the approximate width of the sample to be measured at the thick end of the tubing. Make a cut at a 45 degree angle.
A feral and O-ring must now be installed onto the thick end. Insert this end of the tubing through the hexagonal opening of the feral. Then insert the end of the tubing into the rubber O-ring.
This setup will be screwed into the front of the electrode. Cut a one centimeter length of Zeus small tubing with a sharp razor blade and inspect the ends for a clean cut and an open boar Cut a 10 centimeter piece of the PE 90 tubing using a sharp razor blade. Place a drop of JB weld onto the midpoint of the small tubing using mouth suction.
Draw the small tubing and the weld into the bore of the large tubing and allow this setup to cure overnight. Although it is not shown, a 45 degree cut should be made at the thick end of this tubing, and a feral and o-ring should be installed onto this end. In the same way shown previously.
Disassemble a standard suction electrode unscrew the feral from the front end of the electrode and the BNC connector from the rear. A lower angled side port must now be made on the side of the electrode barrel. Heat up a piece of metal using a bun and burner.
Press the heated metal into the existing hole on the side of the barrel at a low angle. Remove the silver wire from the BNC connector by pulling on the wire where it meets with the connector. Soak the BNC connector in xylene for one hour to remove the wax.
Once the wax is removed, rinse the connector in water and dry with paper towels. Cut a 15 centimeter length of silver wire. Soak the wire in bleach for 15 minutes.
Then rinse and dry with paper towels. Solder the silver wire to the BNC connector. Insert the silver wire into the back end of the suction electrode barrel, and leave enough room for the BNC connector to remain to the side.
Insert the suction tubing into the side port approximately three centimeters. Inject silicone sealant into the back opening of the suction electrode while preventing it from spilling out of the side port by covering it with your finger. Inject sealant approximately two to three centimeters into the electrode barrel.
Once failed, tightly screwed the BNC connector into place, which will push the sealant forward. Let the sealant cure overnight. Screw the feral of the tubing created by either the pulled tip or cut tip method onto the front of the electrode straightening.
The tubing will help ease the silver wire through the electrode is now complete. The recording setup is placed inside a faraday cage to reduce outside interference. Our setup has also been placed on an air table to eliminate mechanical interference.
The electrodes are mounted on magnetic stand micro manipulators and placed near the recording dish. The BNC coaxial cables are connected to a head stage that is connected to an amplifier. The amplifier is wired to a poly view adapter, which is wired to the computer.
This setup is shown closeup. The BNC coaxial cables are connected to a head stage. The head stage is connected to the amplifier.
The amplifier output exits the Faraday cage and is connected to a poly view adapter. The poly view adapter is connected to the computer which has the appropriate recording software installed. The entire setup must be grounded properly.
An external ground is established by connecting the Faraday cage and air table to a ground. An internal ground is established by wiring the dissection dish to the head stage. It is also necessary to ground the doors of the cage to the main body.
With the proper setup data can now be collected. Thank you for watching this video and to help It assist you with your future experiments.
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Overview
This article demonstrates the fabrication and application of extracellular suction electrodes for measuring electrophysiological recordings from neonatal rodent spinal cords in vitro. The process involves using an alcohol lamp to melt plastic tubing into the desired shape.
Key Study Components
Area of Science
- Neuroscience
- Electrophysiology
- Neurobiology
Background
- Extracellular suction electrodes are essential tools for recording electrical activity in neural tissues.
- Understanding spinal cord physiology is crucial for developing treatments for neurological disorders.
- In vitro techniques allow for controlled experimental conditions.
- Neonatal rodent models are commonly used in neuroscience research.
Purpose of Study
- To demonstrate the fabrication of extracellular suction electrodes.
- To illustrate their use in electrophysiological recordings.
- To provide a protocol for researchers in the field.
Methods Used
- Fabrication of electrodes using PE 90 plastic tubing.
- Heating the tubing with an alcohol lamp.
- Shaping the tubing to achieve the desired width.
- Recording electrophysiological signals from spinal cords in vitro.
Main Results
- Successful fabrication of functional extracellular suction electrodes.
- Demonstrated ability to record electrophysiological signals.
- Provided a clear protocol for electrode preparation.
- Highlighted the importance of in vitro recordings in neuroscience research.
Conclusions
- Extracellular suction electrodes are effective for in vitro recordings.
- The fabrication method is accessible for researchers.
- This technique can enhance the understanding of spinal cord physiology.
Frequently Asked Questions
Executive Industry Relevance
Precise electrophysiological measurement of neural circuit activity is critical for de-risking target validation in CNS drug discovery. Fabrication of reliable extracellular suction electrodes enables reproducible assessment of spinal cord central pattern generator function, supporting mechanistic understanding of locomotor networks. This capability enhances predictive confidence in early-stage therapeutic hypothesis testing for movement disorders.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of spinal cord circuitry to validate targets modulating locomotor function.
- Operational Value: Provides a standardized method for recording fictive locomotion in neonatal rodent models.
Screening & Assay Development
- Scientific Value: Generates quantitative neurogram outputs for assessing compound effects on neural rhythm generation.
- Operational Value: Supports assay standardization through consistent electrode fabrication using pulled or cut tubing methods.
Translational & Preclinical Research
- Scientific Value: Facilitates disease-relevant modeling of spinal cord physiology for preclinical target validation.
- Operational Value: Enables continuity from discovery electrophysiology to preclinical efficacy assessment.
Pipeline & Workflow Integration
The method supports discovery biology through direct measurement of neural circuit activity, informing target engagement and pathway modulation studies.
- Discovery Biology: Supports hypothesis testing of therapeutic targets influencing spinal cord network dynamics.
- Screening: Enables reproducible electrophysiological readouts for compound screening in CNS programs.
- Analytics: Provides quantitative neurogram measurements for comparing experimental conditions.
- Translational Research: Connects in vitro findings to preclinical models of motor function.
- Enterprise Reuse: Establishes a reusable electrophysiological capability across multiple CNS discovery projects.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in target validation by reducing mechanistic ambiguity in neural circuit function.
- Operational Value: Enhances reproducibility and standardization of electrophysiological recordings across laboratories.
- Strategic Value: Improves go/no-go decisions by providing direct functional readouts of target modulation.
- Portfolio Impact: Supports risk-adjusted prioritization of CNS targets based on locomotor circuit effects.
Implementation Considerations
- Requires expertise in electrophysiology and microsurgical techniques for spinal cord dissection.
- Depends on specialized equipment including alcohol lamps, precision tubing, and grounding infrastructure.
- Necessitates standardization of electrode fabrication procedures across research teams.
- Involves adaptation considerations for different species or developmental stages of spinal cord preparations.
- Limited by the need for electromagnetic and mechanical shielding to ensure signal fidelity.
