A Hyperflexible Electrode Array for Long-Term Recording and Decoding of Intraspinal Neuronal Activity.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Implantable Devices

Background:

• Neural interfaces are crucial for treating motor dysfunctions by accessing spinal cord (SC) electrical activity.
• Current high-density electrodes face challenges in achieving high channel counts and long-term intraspinal recording due to mechanical mismatch and tissue response.

Purpose of the Study:

• To develop and evaluate a biocompatible, hyperflexible SC electrode array (SHEA) for stable, long-term intraspinal recording.
• To assess the SHEA's performance in terms of signal quality, biocompatibility, and its ability to decode motor activity.

Main Methods:

• Implantation of an ultrathin, biocompatible SC hyperflexible electrode array (SHEA) into mouse SC.
• Evaluation of electrode impedance, signal-to-noise ratio, single-unit yield, and spike amplitude over 2 months.
• Gait analysis and histological examination to assess tissue response and behavioral effects.
• Decoding of mouse movement trajectory using recorded multi-unit signals from the SC ventral horn.

Main Results:

• SHEA demonstrated stable recording performance (impedance, SNR, yield, amplitude) for over 2 months.
• Implantation resulted in negligible behavioral effects and inflammation, indicating good biocompatibility.
• Recorded SC neural signals accurately predicted mouse movement trajectory (decoding coefficient up to 0.95).
• Neural trajectories of spikes and LFPs exhibited periodic patterns during locomotion.

Conclusions:

• The SHEA is a promising neural interface for stable, long-term intraspinal recording.
• It minimizes mechanical mismatch, ensuring high signal quality and biocompatibility.
• SHEA facilitates reliable decoding of motor activity, offering potential for therapeutic interventions in motor dysfunctions.