Referencing--Silicon probes, acute neural recording/stimulation

Technical Note

Document Title: Referencing – Silicon Probes for Acute Neural Recording/Stimulation

Document Number: NN-TN-2025-005

Version: 1.0

Date: March 16, 2025

Author: NeuroNexus Technical Support Team

Revision History: N/A (Initial Release)

Status: Approved for Publication

Intended Audience: Researchers conducting acute neural recording and stimulation using NeuroNexus silicon probes

Application Area: Electrophysiology techniques, electrodes, micro-scale neural interfaces, brain-computer interfaces

Associated Resources:

• surgical guide as a pdf document
• NeuroNexus website

1. Introduction

This technical note provides an overview of best practices for configuring reference and ground connections when using NeuroNexus silicon probes in acute neural recording and stimulation experiments. Proper referencing is crucial for obtaining high-quality neural signals and minimizing artifacts during stimulation.

Detailed configurations may vary by laboratory based on experimental design, equipment, and institutional protocols. This document outlines a general approach to illustrate proper referencing and grounding within the basic procedural framework. Researchers should adapt these recommendations to their specific methodologies while complying with all applicable ethical and regulatory guidelines.

2. Importance of Proper Referencing

In neural recording and stimulation, the reference electrode serves as a baseline for measuring neural activity, while the ground electrode provides a common return path for electrical currents. Incorrect referencing can lead to:

• Increased Noise: Poor signal-to-noise ratio (SNR) due to environmental interference.
• Stimulation Artifacts: Unwanted artifacts that can obscure neural signals during stimulation. citeturn0search9

Proper referencing ensures accurate data acquisition and reliable interpretation of neural activity.

3. Reference and Ground Configurations

a. Reference Electrode Placement

• Separate Reference Electrode:
  • Placement: Insert a stainless steel or Ag/AgCl wire into a saline-filled craniotomy, either contralateral or ipsilateral to the recording site.

  • Connection: Attach the reference wire to the designated reference input on the recording system.

    No Separate Reference:

  • Configuration: Connect the probe's reference input directly to a bone screw placed near the recording site.
  • Consideration: Ensure the bone screw does not penetrate the dura mater to avoid tissue damage.

b. Ground Electrode Placement

• Ground Electrode:
  • Placement: Secure a ground wire to a bone screw positioned away from the recording area to minimize interference.
  • Connection: Attach the ground wire to the ground input on the recording system.

4. Mitigating Stimulation Artifacts

During simultaneous recording and stimulation, artifacts can occur due to electromagnetic interference. To minimize these artifacts:

• Lower Impedance: Utilize electrodes with low impedance to reduce the voltage required for stimulation, thereby decreasing artifact amplitude. citeturn0search9
• Template Subtraction: Implement real-time template subtraction techniques to remove predictable artifacts from the recorded signals. citeturn0search9
• Shielding: Use a Faraday cage to isolate the experimental setup from external electromagnetic interference.