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STRUCTURE-FUNCTION RELATIONSHIPS IN CENTRAL NERVOUS SYSTEM NEURONS ACTIVATED BY EXTRACELLULAR ELECTRIC FIELDS
Lee, Dongchul C

2004, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
The activation of CNS neurons may be initiated by stimulation of different neural elements including axon, dendrites, and cell body, that are exposed to an extracellular electric field. It is not known how the distribution of the electric field impacts the different neural elements. The objective of this research is to understand the structure-function relationships of CNS neurons exposed to extracellular electric fields. The effects of extracellular fields on cell polarization were studied by solving the transmembrane potential generated in a spherical cell in a nonuniform extracellular electric field. The electric field was altered by the presence of the cell, and the pattern of transmembrane potential in the spherical cell was asymmetric. Both of these findings were validated experimentally using voltage-sensitive dyes to image transmembrane potential in oocytes. The effect of field distribution on neuronal excitation was studied by determining the elements of thalamic interneurons and thalamic relay neurons that were stimulated by extracellular electric fields from four different electrode geometries. The axon was more excitable than any other neural element, and the patterns of excitation across the different electrode geometries were remarkably similar. There was spatial heterogeneity of neuronal responses – neurons at similar distance from the electrode but different positions exhibited very different responses, and this offers an explanation for the reported variability in experimental studies. Further, axonal firing could initiate antidromically somatic and dendritic activity, and constant frequency antidromic activity evoked somatic bursting. The effect of the structure of the post-synaptic cell on efficacy of synaptic inputs, as might occur during extracellular stimulation of pre-synaptic axons, was studied by quantifying the effect of changing the location of axon origin (from soma vs. dendrite) on the efficiency of synaptic inputs. The site of axon origin modulated the efficacy of synaptic inputs in generating axonal output, and axons originating on a dendrite increased the differential gain between inputs arriving on different portions of the dendritic tree. These results demonstrate that neural structure plays important roles in determining the output of CNS neurons in response to extracellular stimulation.
Warren Grill (Advisor)
160 p.

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Lee, D. (2004). STRUCTURE-FUNCTION RELATIONSHIPS IN CENTRAL NERVOUS SYSTEM NEURONS ACTIVATED BY EXTRACELLULAR ELECTRIC FIELDS. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Lee, Dongchul. "STRUCTURE-FUNCTION RELATIONSHIPS IN CENTRAL NERVOUS SYSTEM NEURONS ACTIVATED BY EXTRACELLULAR ELECTRIC FIELDS." Electronic Thesis or Dissertation. Case Western Reserve University, 2004. OhioLINK Electronic Theses and Dissertations Center. 22 Aug 2017.

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Lee, Dongchul "STRUCTURE-FUNCTION RELATIONSHIPS IN CENTRAL NERVOUS SYSTEM NEURONS ACTIVATED BY EXTRACELLULAR ELECTRIC FIELDS." Electronic Thesis or Dissertation. Case Western Reserve University, 2004. https://etd.ohiolink.edu/

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