Extraction force and cortical tissue reaction of silicon microelectrode arrays implanted in the rat brain

George C. McConnell, Thomas M. Schneider, D. Jason Owens, Ravi V. Bellamkonda

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Micromotion of implanted silicon multielectrode arrays (Si MEAs) is thought to influence the inflammatory response they elicit. The degree of strain that micromotion imparts on surrounding tissue is related to the extent of mechanical integration of the implanted electrodes with the brain. In this study, we quantified the force of extraction of implanted four shank Michigan electrodes in adult rat brains and investigated potential cellular and extracellular matrix contributors to tissue-electrode adhesion using immunohistochemical markers for microglia, astrocytes and extracellular matrix deposition in the immediate vicinity of the electrodes. Our results suggest that the peak extraction force of the implanted electrodes increases significantly from the day of implantation (day 0) to the day of extraction (day 7 and day 28 postimplantation) (1.68 ± 0.54 g, 3.99 ± 1.31 g, and 4.86 ± 1.49 g, respectively; mean ± SD; n=4). For an additional group of four shank electrode implants with a closer intershank spacing we observed a significant increase in peak extraction force on day 28 post implantation compared to day 0 and day 7 postimplantation (5.56 ± 0.76 g, 0.37 ± 0.12 g and 1.87 ± 0.88 g, respectively; n=4). Significantly, only glial fibrillary acidic protein (GFAP) expression was correlated with peak extraction force in both electrode designs of all the markers of astroglial scar studied. For studies that try to model micromotion-induced strain, our data implies that adhesion between tissue and electrode increases after implantation and sheds light on the nature of implanted electrode-elicited brain tissue reaction.

Original languageEnglish
Pages (from-to)1097-1107
Number of pages11
JournalIEEE Transactions on Biomedical Engineering
Volume54
Issue number6
DOIs
StatePublished - Jun 2007

Keywords

  • Astroglial scar
  • Chronic recordings
  • Force measurement
  • Immunohistochemistry
  • Microelectrodes
  • Micromotion
  • Neuroprostheses

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