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The Glia-Neuronal Response to Cortical Electrodes: Interactions with Substrate Stiffness and Electrophysiology

Harris, James Patrick
http://rave.ohiolink.edu/etdc/view?acc_num=case1320950439

Abstract Details

2011, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
The overall goal of this work is to improve intracortical electrodes for chronic recordings from the brain. The studies in the dissertation examine material stiffness, the tissue response, and electrode recording quality to enable improvements. Intracortical electrodes can improve the quality of life of patients with severe paralysis via brain machine interfaces (BMIs), but factors limit electrode widespread clinical usage. One factor of implanted intracortical electrodes is that the number of recorded signals decreases over time, limiting the longevity of electrodes. The decrease is hypothesized to be from the tissue response to the electrodes. In this dissertation, we investigate the tissue response and its effect on electrode recordings. Specifically, we examine the role of material stiffness on the tissue response. Recently developed, a mechanically adaptive nanocomposite decreases its stiffness from 5 GPa to 12 MPa in vitro. Confirming in vitro work, we show that the nanocomposite is stiff enough for insertion, but softer than traditional BMI electrodes after brain implantation. The nanocomposite enables our examination of the role of material stiffness on tissue response. Implanting the soft nanocomposite and surface-matched stiff microwire, we examine the effect of stiffness on tissue response. At one month, greater neural density around the nanocomposite versus the microwire accompanies changes in mechanically associated factors, intermediate filaments and extracellular matrix components. At two months, the neural densities are similar between implant types, and neural density around the nanocomposite is maintained despite macrophage activation. The soft nanocomposite modifies the tissue response, and therefore, we examine whether the tissue response affects neural recordings. By using lipopolysaccharide (LPS) to promote the inflammatory response, LPS-treated animals show an increase in non-neural cells and a decrease in the neural cells near the implant. Additionally, the quality of recordings is reduced in LPS-treated animals. Though further research is necessary, the results of this work support the hypothesis that a softer material can improve long-term neural recording. The work guides electrode development to improve electrodes to offer patients with severe paralysis and other neurological deficits a better quality of life.
Dustin Tyler (Committee Chair)
Jeffery Capadona (Committee Member)
Robert Miller (Committee Member)
Dawn Taylor (Committee Member)
Christoph Weder (Committee Member)
Biomedical Engineering
Brain; Neural Prosthesis; micromotion; cellulose; Cell encapsulation; electrode; Inflammation; Mechanical properties; Nanocomposite; Young&8217; s Modulus; Insertion Force

Recommended Citations

Citations

  • Harris, J. P. (2011). The Glia-Neuronal Response to Cortical Electrodes: Interactions with Substrate Stiffness and Electrophysiology [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1320950439

    APA Style (7th edition)

  • Harris, James. The Glia-Neuronal Response to Cortical Electrodes: Interactions with Substrate Stiffness and Electrophysiology. 2011. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1320950439.

    MLA Style (8th edition)

  • Harris, James. "The Glia-Neuronal Response to Cortical Electrodes: Interactions with Substrate Stiffness and Electrophysiology." Doctoral dissertation, Case Western Reserve University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1320950439

    Chicago Manual of Style (17th edition)

case1320950439
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© 2011, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.