2022 Fiscal Year Annual Research Report
| Project/Area Number |
22F22077
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| Allocation Type | Single-year Grants |
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
McHugh Thomas 国立研究開発法人理化学研究所, 脳神経科学研究センター, チームリーダー (50553731)
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| Co-Investigator(Kenkyū-buntansha) |
HE HONGSHEN 国立研究開発法人理化学研究所, 脳神経科学研究センター, 外国人特別研究員
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| Project Period (FY) |
2022-04-22 – 2024-03-31
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| Keywords | hippocampus / medial septum / spatial memory / locomotion / connectome |
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| Outline of Annual Research Achievements |
The last fiscal year focused on addressing the anatomical connectome of CA2 using viral tracing methods. To map the brain-wide connections, several transgenic mouse lines were applied, along with an unsupervised machine learning approach to reveal divergent phenotypes, especially highlighting the hippocampal-medial septum circuits. These results help to lay the foundation for designing behavioral experiments. Meanwhile, to dissect the physiological features of CA2 during memory information routing, analysis at the single-cell and population level revealed a novel role for CA2 in mediating hippocampal dynamics under discrete behavioral states. Such results were also compared and reviewed with previous works to suggest a unique role of CA2 during memory processing.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The ongoing project has revealed several intuitive results. First, it is generally consistent with published literature but has uncovered novel connections among the cortical, forebrain, and hippocampal loops. Such novel connections imply new functions that CA2 might share. Second, the calcium imaging combined with behavioral dissection suggests that the hippocampus follows a simple stimulus-response rule but pinpoints a computational role in prioritizing information during behavior selection, which highly relies on several key pathways from both cortical and forebrain structures. Finally, the electrophysiological recordings have revealed consistent outcomes on a much finer time-scale. These results will lead to more insightful conclusions.
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| Strategy for Future Research Activity |
The next fiscal year aims to finish collecting all behavioral and physiological data, and to conduct detailed analysis. Further, to address the causal relationship between CA2 circuits and their functions, optogenetic manipulation will be applied to temporarily activate or inhibit both inputs and outputs. The perturbation results will be compared with both anatomical and behavioral outcomes to understand how the cortical, forebrain, and hippocampal loops impact sophisticated behaviors.
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