2018 Fiscal Year Research-status Report
Synaptic organizational principles in a subset of brain regions
| Project/Area Number |
18K14842
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| Research Institution | Juntendo University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | Dendritic Spine / Dendrite / FIB/SEM / Synapses / Synaptic organisation |
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| Outline of Annual Research Achievements |
By large-scale reconstruction of neuropil by FIB/SEM and fully manual segmentation of dendrites from different brain regions, we provide a through qualitative and quantitative description of the morphological features of dendritic shafts and their spines. We show that the summated postsynaptic density (PSD) area per unit length of dendrite increases with dendritic diameter. Using two photon glutamate uncaging and electrophysiological recording, we show that the dendrites of similar diameter produces same magnitude of excitatory postsynaptic current response. Computer simulation suggested that the functional constancy in dendritic diameter enables maximal information transfer to soma. In summary, we report common and unique features across various brain regions that contain spiny neurons.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
We have succeeded in full manual reconstruction of 2082 dendritic spines and 86 dendritic shafts from CA1 stratum radiatum, CA1 stratum laconosum moleculare, CA3, cortex and cerebellum. Because of the availability of FIB/SEM imaging facility in Juntendo University, image acquisition went smoothly as planned. By quantifying such a large number of spines, we were also able to reveal novel organizational principle of synapses in a dendrite. In the brain regions where cell body are organized in a laminar fashion, the summated PSD area of dendritic spines scaled positively with the dendritic diameter. Electrophysiological data supports our finding from the morphological studies that the dendrites of similar diameter produces similar magnitude of summated synaptic response.
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| Strategy for Future Research Activity |
We have not yet shown if the molecules that govern synaptic strength such as AMPA receptor (AMPAR) scales positively with the PSD size of individual spines and the dendritic diameter. This information will be necessary to supplement our finding from the FIB/SEM reconstruction of dendritic spines. For this, we are planning to do SDS-digested freeze fracture replica labeling (SDS-FRL) to quantify the number of AMPAR in individual spines. I will learn SDS-FRL technique in collaboration with Dr. Yugo Fukazawa in Fukui University. Similarly, in collaboration with Dr. Shigeo Okabe`s lab at the University of Tokyo we have performed In vivo Imaging of AMPAR content in cortical dendrites. I plan to analyze this data and show if the total AMPAR content scales positively with dendritic diameter.
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| Causes of Carryover |
We were initially planning to take FIB/SEM images from different layers of cortex and other spiny brain regions such as Amygdala. However, since the image analysis takes a long time and we were able to decipher the synaptic organizational principle by images from CA1 striatum radiatum, CA1 stratum laconosum moleculare, cortex, CA3, striatum and cerebellum, we decided not to proceed with the imaging of additional brain regions. Thus, the amount incurred for FIB/SEM analysis was lesser than we expected. We will use this money in the next fiscal year by buying antibodies for synaptic molecules.
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[Journal Article] Near-infrared deep brain stimulation via upconversion nanoparticle-mediated optogenetics2018
Author(s)
Shuo Chen, Adam Z. Weitemier, Xiao Zeng, Linmeng He, Xiyu Wang, Yanqiu Tao, Arthur J. Y. Huang, Yuki Hashimotodani, Masanobu Kano, Hirohide Iwasaki, Laxmi Kumar Parajuli, Shigeo Okabe, Daniel B. Loong Teh, Angelo H. All, Iku Tsutsui-Kimura, Kenji F. Tanaka, Xiaogang Liu, Thomas J. McHugh
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Journal Title
Science
Volume: 359 (6376)
Pages: 679-684
DOI
Peer Reviewed / Open Access / Int'l Joint Research
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[Journal Article] Kv2 ion channels determine the expression and localization of the associated AMIGO-1 cell adhesion molecule in adult brain neurons2018
Author(s)
Bishop HI, Cobb MM, Kirmiz M, Parajuli LK, Mandikian D, Philp AM, Melnik M, Kuja-Panula J, Rauvala H, Shigemoto R, Murray KD, Trimmer JS
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Journal Title
Front Mol Neurosci
Volume: 11:1
Pages: -
DOI
Peer Reviewed / Open Access / Int'l Joint Research
