Characterization tools and paradigms for understanding the electrode-tissue interface (electrophysiology and 2 photon microscopy)
Many studies on characterizing and improving the tissue compatibility of neural electrodes were performed with non-functional arrays. Using non functional arrays, dummy probes that do not have electrical connection for recording, there is no way to tell if a specific biological response is related to electrode performance, and whether a biomaterial strategy brings any benefit on neural recording. Deviating from these studies, we use functional electrode arrays and evaluate the recording performance over time with two sensory-evoked chronic animal recording models, a visual stimulation model and a whisker stimulation model.
Furthermore, the studies of electrode-tissue interface have been primarily using discrete endpoint post-mortem histology. This limits the degree to which dynamic changes can be studied during and after probe implantation. Furthermore, the removal of the implant in most of these studies inevitably destroys the tissue interface. Our team has adapted the multiphoton imaging technology and established an unique experimental setup to observe the dynamic changes in microglial cells and vasculature during and after microelectrode implantation over time. The initial findings show great promise for expanding scientific knowledge at this tissue interface. Combining imaging with electrical recording will enable more accurate correlation of cellular response and recording performance.
Example publications include:
- Kozai, TDY, Vazquez AL, Weaver CL, Kim SG, Cui XT. In vivo two photon microscopy reveals immediate microglial reaction to implantation of microelectrode through extension of processes. J Neural Eng. 2012. 9. 066001.
- Takashi DY Kozai, Zhanhong Du, Zhannetta V Gugel, Matthew A Smith, Steven M Chase, Lance M Bodily, Ellen M Caparosa, Robert M Friedlander, X Tracy Cui, Comprehensive chronic laminar single-unit, multi-unit, and local field potential recording performance with planar single shank electrode arrays, J. Neuroscience Methods, 2015, 242, 15-40.
- Zhanghong Du, Xiliang Luo, Cassandra Weaver, X. Tracy Cui, Poly (3, 4-ethylenedioxythiophene)-ionic liquid coating improves neural recording and stimulation functionality of MEAs, Journal of Materials Chemistry C, 2015, 3, 6515-6524; DOI: 10.1039/C5TC00145E
- Takashi DY Kozai, James R Eles, Alberto L Vazquez, X Tracy Cui, Two-photon imaging of chronically implanted neural electrodes: Sealing methods and new insights, Journal of Neuroscience Methods, available on line 2015/10/23