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Mechanisms of High Sensitivity and Active Amplification in Sensory Hair Cells

Khamesian, Mahvand

Abstract Details

2018, Doctor of Philosophy (PhD), Ohio University, Social Sciences (Arts and Sciences).
Hair cells mediating the senses of hearing and balance rely on active mechanisms for amplification of mechanical signals. In amphibians, hair cells exhibit spontaneous self-sustained mechanical oscillations of their hair bundles. In addition to mechanical oscillations, it is known that the electrical resonance is responsible for frequency selectivity in some inner ear organs. Furthermore, hair cells may show spontaneous electrical oscillations of their membrane potentials. In this dissertation, we study these mechanisms using a computational modeling of the bullfrog sacculus, a well-studied preparation in sensory neuroscience. In vivo, hair bundles of the bullfrog sacculus are coupled by an overlying otolithic membrane across a significant fraction of epithelium. We develop a model for coupled hair bundles in which non-identical hair cells are distributed on a regular grid and coupled mechanically via elastic springs connected to the hair bundles. We first refine a model of a single hair bundle and study the effect of membrane potential on mechanical oscillations and sensitivity of sensory hair cells. In particular, we show that the fast adaptation is necessary to account for the experimentally observed responses to variations of the membrane potential. We then study the collective dynamics of coupled hair bundles and their response to mechanical and electrical stimuli. Our simulations of coupled hair bundles identify two distinct regimes of collective spontaneous dynamics: oscillation quenching and synchronization. The former regime is experimentally observed in bullfrog sacculus. We characterize stimulus-detection properties of the coupled hair bundles and show that coupling-induced suppression of spontaneous oscillations enhances stimulus discrimination. We further analyze the collective response of coupled hair bundles to variations of the membrane potential. We show that these variations may alter mechanical response significantly and thus may yield an effective mechanism of sensitivity enhancement and gain control.
Alexander Neiman (Advisor)
118 p.

Recommended Citations

Citations

  • Khamesian, M. (2018). Mechanisms of High Sensitivity and Active Amplification in Sensory Hair Cells [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou153243238506078

    APA Style (7th edition)

  • Khamesian, Mahvand. Mechanisms of High Sensitivity and Active Amplification in Sensory Hair Cells. 2018. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou153243238506078.

    MLA Style (8th edition)

  • Khamesian, Mahvand. "Mechanisms of High Sensitivity and Active Amplification in Sensory Hair Cells." Doctoral dissertation, Ohio University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou153243238506078

    Chicago Manual of Style (17th edition)