Title: Simulation of the synaptic exocytosis of bipolar cells in the electrically stimulated mammalian retina
Other Titles: Simulation der Neurotransmitterausschüttung von Bipolarzellen der elektrisch stimulierten Retina
Language: English
Authors: Bassereh Moosaabadi, Hassan 
Qualification level: Doctoral
Advisor: Rattay, Frank 
Issue Date: 2019
Bassereh Moosaabadi, H. (2019). Simulation of the synaptic exocytosis of bipolar cells in the electrically stimulated mammalian retina [Dissertation, Technische Universität Wien]. reposiTUm. https://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-126035
Number of Pages: 148
Qualification level: Doctoral
The output of the retinal bipolar neurons has two components, i.e., transient and sustained neurotransmitter releases, which is not common at chemical synapses. This uniqueness originates from an extra protein structure called 'ribbon'. Transient outputs take place exactly after a large enough stimulus, while sustained outputs occur at any state with a different rate. We presented two models to simulate both releases from a terminal of a rat rod bipolar cell, but the approach can be applied for any type of bipolar cells. One of the models is based on transmembrane voltage of terminals and the other is based on intracellular calcium concentration of terminals, each of which is explained by two time dependent equations. Intracellular calcium concentration method bring a 0.43 ms signal delay observable in xperiments, while the other model has no delay. By comparing responses of spiking and non-spiking bipolar cells stimulated intracellularly, it was proposed that a spike causes the release of all of the available vesicles rapidly (transient releases), while the non-spiking cell release no vesicle at the same stimulus amplitude. Effect of extracellular stimulation generated by a single microelectrode, on transient release almost suggested no difference between responses of active and passive cells in short pulses because terminal membrane of the cells in both cases senses the same potentials originating from the microelectrode. However, spiking-bipolar cells release more transient vesicles in pulses with long duration since spike has enough time to reach to the terminal leading to release of more transient vesicles. Effect of periodic stimulation on ribbon recovery when the cell is stimulated both intraor extracellularly also suggested that for 5 Hz stimulations, only three transient vesicles are released from a single ribbon per stimulus.
Keywords: ribbon synapse; retina; bipolar cell; stimulation; simulation
URI: https://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-126035
Library ID: AC15391421
Organisation: E101 - Institut für Analysis und Scientific Computing 
Publication Type: Thesis
Appears in Collections:Thesis

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