High-density penetrating array dorsal root ganglia recordings

Study Purpose: Dorsal root ganglia (DRG) are promising sites for recording sensory activity. Current technologies for DRG recording are stiff and typically do not have sufficient site density for high-density neural data techniques. Here we demonstrate acute neural recordings in feline sacral DRG using a flexible polyimide microelectrode array with 30-40 μm site spacing.

Data Collection: We delivered arrays into DRG with ultrananocrystalline diamond shuttles designed for high stiffness with a small footprint. We recorded neural activity during sensory activation, including cutaneous brushing and bladder filling.

Primary Conclusion: We successfully delivered arrays in 5/6 experiments and recorded sensory activity in 4. The median signal amplitude was 55 μV and the maximum unique units recorded at one position was 260, with 157 driven by sensory or electrical stimulation. We used specialized high-density neural signal analysis software to sort neural signals and, in one experiment, track 8 signals as the array was retracted ~500 μm. This study is the first demonstration of ultrathin, flexible, high-density electronics delivered into DRG, with capabilities for recording and tracking sensory information a significant improvement over conventional DRG interfaces.

Curator's Notes

Experimental Design: A high-density flexible polyimide electrode array was fabricated and inserted into the sacral DRG of an anesthetized feline for neural recordings. Sensory neurons were activated by performing bladder cystometry, dermatome brushing, or nerve cuff electrical stimulation (pudendal nerve and pelvic nerve are lower urinary tract nerves in the sacral DRG). Neural signals were sampled at 30 kHz with a Neural Interface Processor (Grapevine, Ripple, Salt Lake City, Utah, USA).

Completeness: This dataset is a part of a larger study, "High-Density Penetrating Array Dorsal Root Ganglia Recordings."

Subjects & Samples: Adult male (n=6) domestic cats were used in this study.

Primary vs derivative data: Primary data is organized in folders by subject ID containing the stimulation data saved at 30 kS/s in the .nev file format. Derivative data contains neural signals sorted in Offline Sorter (Plexon, Dallas, TX, USA) and analyzed with custom scripts in MATLAB (Mathworks, Nantick, MA, USA).

Code Availability: Raw neural data can be analyzed using IronClust software. Details of using this software are available at the repository. IronClust requires MATLABb 2016 or later. https://github.com/flatironinstitute/ironclust