Objective. The dorsal root ganglia (DRG) are promising nerve structures for sensory neural interfaces because they provide centralized access to primary afferent cell bodies and spinal reflex circuitry. In order to harness this potential, new electrode technologies are needed which take advantage of the unique properties of DRG, specifically the high density of neural cell bodies at the dorsal surface. Here we report initial in vivo results from the development of a flexible non-penetrating polyimide electrode array interfacing with the surface of ganglia. Approach. Multiple layouts of a 64-channel iridium electrode (420 m2) array were tested, with pitch as small as 25 m. The buccal ganglia of invertebrate sea slug Aplysia californica were used to develop handling and recording techniques with ganglionic surface electrode arrays (GSEAs). We also demonstrated the GSEA's capability to record single- and multi-unit activity from feline lumbosacral DRG related to a variety of sensory inputs, including cutaneous brushing, joint flexion, and bladder pressure. Main results. We recorded action potentials from a variety of Aplysia neurons activated by nerve stimulation, and units were observed firing simultaneously on closely spaced electrode sites. We also recorded single- and multi-unit activity associated with sensory inputs from feline DRG. We utilized spatial oversampling of action potentials on closely-spaced electrode sites to estimate the location of neural sources at between 25 m and 107 m below the DRG surface. We also used the high spatial sampling to demonstrate a possible spatial sensory map of one feline's DRG. We obtained activation of sensory fibers with low-amplitude stimulation through individual or groups of GSEA electrode sites. Significance. Overall, the GSEA has been shown to provide a variety of information types from ganglia neurons and to have significant potential as a tool for neural mapping and interfacing.
Bibliographical noteFunding Information:
This work was a collaboration between the Bruns Peripheral Neural Engineering and Urodynamics Laboratory (pNEURO Lab), the Yoon Lab, and the Chiel Lab. The authors would therefore like to thank the members of those laboratories for support and advice in designing, fabricating, and testing the surface array. In particular, we acknowledge Aileen Ouyang, Ahmad Jiman, Lauren Zimmerman, Shani Ross, Henry Hilow, Nicholas Peck-Dimit, John Bentley, Catherine Kehl, Hui Lu, and Fan Wu. We also thank Evan Kellar for the gracious use of his aquatics room. Research reported in this publication was supported by the Craig H Neilsen Foundation (Grant # 314980), the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health (SPARC program Award # U18EB021760), the Michigan Institute for Clinical and Health Research, which is funded by the National Center for Advancing Translational Studies of the National Institutes of Health (Grant #’s UL1TR000433 and UL1TR002240), and Seed Funding for Innovative Projects in Neuroscience from the Michigan Brain Initiative Working Group (MiBrain). The content is solely the responsibility of the authors and does not necessarily represent the official views of the Craig H Neilsen Foundation, the National Institutes of Health, or the University of Michigan.
All Science Journal Classification (ASJC) codes
- Biomedical Engineering
- Cellular and Molecular Neuroscience