Boris Delipetar1,2, Tonći Kozina3, Jelena Žarković1,2, Ana Bedalov4, Damir Kovačić1,2,3

1The Center of Research Excellence for Science and Technology Integrating Mediterranean region (STIM), University of Split, Croatia; 2Laboratory for Biophysics and Medical Neuroelectronics, Department of Physics, University of Split-Faculty of Science, Croatia; 3Auditory Research Laboratory, University of Split, Split, Croatia; 4 The doctoral program in Biophysics, University of Split-Faculty of Science, Croatia

Methods for neural response properties, i.e., triggering action potentials (AP) of spiral ganglion neurons (SGN), are still not thoroughly explored and quantified. We report a new neuroelectronic interface consisting of an operational amplifier, printed circuit boards (PCB) and silicon-based high-density electrode array for this study. The significance of this new interface lays in the capability of performing multiple individual stimulation and recording on 64 electrodes simultaneously. Furthermore, a MATLAB application has been designed and implemented to perform the analysis of acquired data. In this study, a silicon-based chip, morphologically optimized for spiral ganglion neurons ([1], [2]), previously coated with poly-L-ornithine and laminin, was used as a surface for in-vitro growth of neonatal SGN extracted from rat pups. After three and six days in-vitro, respectively (3 and 6 DIV), SGN cultures on silicon-based chips, previously bonded on PCBs, were connected to a neuroelectronic interface, and bursts of spontaneous action potentials were recorded. Also, SGN cultures were stimulated with different current amplitudes, phase durations, and modes of stimulation. Results have shown various types of obtained signals regarding their amplitude, latency, duration, polarity, and repeatability. Some of the obtained spontaneous signals match in some characteristics with previously reported properties of action potential signals. Properties of stimulation responses were also analyzed. These findings are then discussed in light of the potential application of the high-density stimulation-recording setup with the graphene-based substrates.

Acknowledgments: “This research was partially supported under the project STIM – REI, Contract Number: KK., a project funded by the European Union through the European Regional Development Fund – the Operational Programme Competitiveness and Cohesion 2014-2020 (KK.” BP has been fully supported by the “Young researchers’ career development project – training of doctoral students” of the Croatian Science Foundation funded by the European Union from the European Social Fund.

[1]   M. Mattotti, L. Micholt, D. Braeken, and D. Kovačić, “Characterization of spiral ganglion neurons cultured on silicon micro-pillar substrates for new auditory neuro-electronic interfaces,” Journal of Neural Engineering, vol. 12, no. 2, 2015.

[2]   V. Radotić, D. Braeken, P. Drviš, M. Mattotti, and D. Kovačić, “Advantageous environment of micro-patterned, high-density complementary metal-oxide-semiconductor electrode array for spiral ganglion neurons cultured in vitro,” Scientific Reports, vol. 8, no. 1, 2018.

Presenting author e-mail address: boris.delipetar@pmfst.hr