thesis published David Kleindienst author 42E121A4-F248-11E8-B48F-1D18A9856A87 Ryuichi Shigemoto supervisor GradSch department RySh department Left-right asymmetries can be considered a fundamental organizational principle of the vertebrate central nervous system. The hippocampal CA3-CA1 pyramidal cell synaptic connection shows an input-side dependent asymmetry where the hemispheric location of the presynaptic CA3 neuron determines the synaptic properties. Left-input synapses terminating on apical dendrites in stratum radiatum have a higher density of NMDA receptor subunit GluN2B, a lower density of AMPA receptor subunit GluA1 and smaller areas with less often perforated PSDs. On the other hand, left-input synapses terminating on basal dendrites in stratum oriens have lower GluN2B densities than right-input ones. Apical and basal synapses further employ different signaling pathways involved in LTP. SDS-digested freeze-fracture replica labeling can visualize synaptic membrane proteins with high sensitivity and resolution, and has been used to reveal the asymmetry at the electron microscopic level. However, it requires time-consuming manual demarcation of the synaptic surface for quantitative measurements. To facilitate the analysis of replica labeling, I first developed a software named Darea, which utilizes deep-learning to automatize this demarcation. With Darea I characterized the synaptic distribution of NMDA and AMPA receptors as well as the voltage-gated Ca2+ channels in CA1 stratum radiatum and oriens. Second, I explored the role of GluN2B and its carboxy-terminus in the establishment of input-side dependent hippocampal asymmetry. In conditional knock-out mice lacking GluN2B expression in CA1 and GluN2B-2A swap mice, where GluN2B carboxy-terminus was exchanged to that of GluN2A, no significant asymmetries of GluN2B, GluA1 and PSD area were detected. We further discovered a previously unknown functional asymmetry of GluN2A, which was also lost in the swap mouse. These results demonstrate that GluN2B carboxy-terminus plays a critical role in normal formation of input-side dependent asymmetry. https://research-explorer.ista.ac.at/download/9562/9563/Thesis.pdf application/pdf2022-07-01no https://research-explorer.ista.ac.at/download/9562/9564/Thesis_source.zip application/zip Institute of Science and Technology Austria2021 eng 2663-337X10.15479/at:ista:9562 124 https://research-explorer.ista.ac.at/record/9756 https://research-explorer.ista.ac.at/record/9437 https://research-explorer.ista.ac.at/record/612 https://research-explorer.ista.ac.at/record/8532 D. Kleindienst, 2B or Not 2B: Hippocampal Asymmetries Mediated by NMDA Receptor Subunit GluN2B C-Terminus and High-Throughput Image Analysis by Deep-Learning, Institute of Science and Technology Austria, 2021. Kleindienst D. 2021. 2B or not 2B: Hippocampal asymmetries mediated by NMDA receptor subunit GluN2B C-terminus and high-throughput image analysis by Deep-Learning. Institute of Science and Technology Austria. Kleindienst, David. “2B or Not 2B: Hippocampal Asymmetries Mediated by NMDA Receptor Subunit GluN2B C-Terminus and High-Throughput Image Analysis by Deep-Learning.” Institute of Science and Technology Austria, 2021. <a href="https://doi.org/10.15479/at:ista:9562">https://doi.org/10.15479/at:ista:9562</a>. Kleindienst D. 2B or not 2B: Hippocampal asymmetries mediated by NMDA receptor subunit GluN2B C-terminus and high-throughput image analysis by Deep-Learning. 2021. doi:<a href="https://doi.org/10.15479/at:ista:9562">10.15479/at:ista:9562</a> D. Kleindienst, “2B or not 2B: Hippocampal asymmetries mediated by NMDA receptor subunit GluN2B C-terminus and high-throughput image analysis by Deep-Learning,” Institute of Science and Technology Austria, 2021. Kleindienst, David. <i>2B or Not 2B: Hippocampal Asymmetries Mediated by NMDA Receptor Subunit GluN2B C-Terminus and High-Throughput Image Analysis by Deep-Learning</i>. Institute of Science and Technology Austria, 2021, doi:<a href="https://doi.org/10.15479/at:ista:9562">10.15479/at:ista:9562</a>. Kleindienst, D. (2021). <i>2B or not 2B: Hippocampal asymmetries mediated by NMDA receptor subunit GluN2B C-terminus and high-throughput image analysis by Deep-Learning</i>. Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:9562">https://doi.org/10.15479/at:ista:9562</a> 95622021-06-17T14:10:47Z2026-04-08T07:12:31Z