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SELF-PROPAGATING, NON-SYNAPTIC HIPPOCAMPAL WAVES RECRUIT NEURONS BY ELECTRIC FIELD COUPLING

Shivacharan, Rajat S
http://orcid.org/0000-0001-6824-4368
http://rave.ohiolink.edu/etdc/view?acc_num=case1554920779970426

Abstract Details

2019, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
It is well documented that synapses play a significant role in the transmission of information between neurons. However, in the absence of synaptic transmission, neural activity has been observed to continue to propagate. This raises the question as to what is mediating this propagation. Previous experiments in our lab have shown that spontaneous epileptiform waves in rodent hippocampi propagates at a speed of ~0.1 m/sec. This observed propagation can take place in the absence of synaptic transmission and gap junctions, and its speed does not correspond to that of ionic diffusion or axonal conduction. Computer simulations indicate that ephaptic coupling, or electric fields, could be responsible for this propagation of neural activity in pathological conditions such as epilepsy. However, there is no experimental data suggesting ephaptic coupling is a critical mechanism for spontaneous, self-regenerating propagation of neural activity. Using in vitro and in vivo experiments complemented by computational modeling, we test the hypothesis that ephaptic coupling is a critical mechanism for self-propagating, non-synaptic hippocampal wave propagation. We first show that spontaneous epileptiform waves self-propagate by endogenous electric field by carrying out a series of experiments that modify the extracellular space and the endogenous field. Second, we show that spontaneous waves xvii are non-synaptic, self-propagating waves mediated by ephaptic field coupling by showing that epileptiform waves can propagate through a complete physical cut of the tissue, therefore, eliminating all other forms of close cell-to-cell communication and showing that electric fields alone are sufficient to mediate non-synaptic propagation. Finally, we show that electric fields can explain not only pathological waves traveling in the brain but can also explain travelling physiological waves such as slow oscillation sleep waves. The findings from this study lay the foundation of the role of electric field coupling as a non-synaptic mechanism in the brain that could have significant importance on brain wave under both pathological and physiological conditions.
Dominique Durand, PhD (Advisor)
Jeffrey Capadona, PhD (Committee Chair)
Cameron McIntyre, PhD (Committee Member)
Hillel Chiel, PhD (Committee Member)
188 p.
Biomedical Engineering; Neurosciences
Epilepsy; Sleep Waves; Non-synaptic Propagation; Electric Fields; Ephaptic Coupling

Recommended Citations

Citations

  • Shivacharan, R. S. (2019). SELF-PROPAGATING, NON-SYNAPTIC HIPPOCAMPAL WAVES RECRUIT NEURONS BY ELECTRIC FIELD COUPLING [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1554920779970426

    APA Style (7th edition)

  • Shivacharan, Rajat. SELF-PROPAGATING, NON-SYNAPTIC HIPPOCAMPAL WAVES RECRUIT NEURONS BY ELECTRIC FIELD COUPLING. 2019. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1554920779970426.

    MLA Style (8th edition)

  • Shivacharan, Rajat. "SELF-PROPAGATING, NON-SYNAPTIC HIPPOCAMPAL WAVES RECRUIT NEURONS BY ELECTRIC FIELD COUPLING." Doctoral dissertation, Case Western Reserve University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1554920779970426

    Chicago Manual of Style (17th edition)

case1554920779970426
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© 2019, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.