2020 Fiscal Year Research-status Report
Dissecting the cortical and subcortical pathways of innate visual fear in the common marmoset
| Project/Area Number |
20K22684
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| Research Institution | Kyoto University |
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Principal Investigator |
CHEN Chih・Yang 京都大学, 高等研究院, 特定助教 (30884689)
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| Project Period (FY) |
2020-09-11 – 2022-03-31
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| Keywords | Innate fear / Marmoset / Electrophysiology / Optogenetics |
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| Outline of Annual Research Achievements |
Innate fear is a type of negative emotion that even if one did not learn or experience before, one is afraid of it. For animals, this is related to survival, because they have to know their predators before experiencing to be captured. Until now, the neuronal mechanisms of innate fear in primate are still largely unknown. With the support of Kakenhi research start-up funding, I am performing a series of experiments trying to reveal the origin of visual innate fear and the potential neuronal networks that convey it using a small new world monkey, the common marmoset.
I am training marmosets to sit in front of a monitor and display innate fear-related pictures, such as snakes and spiders. At the meantime, we are also recording their eye movements, pupillary responses, heart rates, and blood pressure to objectively observe if they express fear-related biological signs. To probe the underlying neuronal mechanisms, I am designing and implanting a brain-wide, full-hemispheric electrocorticography (ECoG) to record their brain activity starting from the primary visual cortex all the way to the prefrontal cortex during the task. This technic will help me to determine the brain areas that respond to fear-related differently than non-fear related pictures. I am also developing optogenetic manipulation techniques to further silence or activate the brain regions to further establish the causality of fear-related responses to those brain areas.
With the above experiments, I expect that I can clarify the potential neuronal networks and brain regions that are related to visual innate fear.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
In the proposed experiments from this research, there are three major parts.
The first one is to prepare for instruments. I have designed and tested two different ECoG design from separate companies in marmosets. The material used from first company was not compatible with marmoset’s brain. It caused allergic reaction to the dura and I lost the marmoset. However, the material from the second company seems fine. I am currently perfecting my skill for the implanting operation and post-operation care. I have also setup the blood pressure and heart rate recording system for marmosets.
The second step is to train the marmosets to perform fear-related picture viewing task. I have successfully trained two marmosets on this task and collected eye movement data and pupillary responses. The results showed that there were significantly different eye movement pattern and pupillary responses when viewing fear-related pictures than not fear-related pictures.
The third step is to change brain activities with optogenetic tools. For this step, I have tested the viral vector for optogenetics in rats. The expression was strong and stable.
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| Strategy for Future Research Activity |
All the current experiments demonstrated that the technics I proposed are feasible. This year, I will continue to challenge implantation of the full-hemispheric ECoG in marmosets. After the ECoG implantation is well-established, I will start recording the neuronal responses while the marmosets are performing the fear-related picture viewing task. By combining the task and recording, I believe I can gather high quality data to dissect the potential pathway of visual innate fear. With separate marmosets, I will also try to inject viral vector and develop the technic to optogenetically change the brain activity and record behavioral changes. By combining the above technics, I believe I will be able to achieve what I proposed at the beginning. At the meantime, I will also publish the behavioral result (eye movements and pupillary response) related to the task in the current year.
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| Causes of Carryover |
I am planning to purchase two more sets of ECoGs but they did not come this fiscal year.
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