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Profile
Welcome! I am a Research Fellow at the Center for Brain Science in Harvard University. I have been fascinated by animals since my childhood, and have a strong background in behavior, awake electrophysiology, anatomy and molecular biology. I was graduated from Kyoto University in 1992 and acquired PhD in Kyoto University (Masatoshi Takeichi Lab) in 1998. I moved to Tokyo Metropolitan Institute (Atsuko Sehara Lab) as a staff scientist, and then worked in Cold Spring Harbor Laboratory (Linda Van Aelst Lab) and Harvard University (Nao Uchida Lab) as a postdoctoral fellow, before earning an independent position in 2013. My lab is interested in the neural mechanism of natural behaviors driven by curiosity, threat and reward. Our current focuses include the mechanism of threat-coping when animals must overcome a potential threat, and how animals explore when they do not know whether a novel object poses threat or reward, and the development of curiosity, threat avoidance and reward learning in the young. My hobbies beyond research are watching wild animals, growing vegetables and swimming.
Research
Research
Threat-coping
Threat-coping
In the natural environments, animals often face situations that can lead to both a potential reward and a potential threat. Animals want to acquire rewards but need to avoid threats for survival. How do they decide what to do? A simple learning theory often aims to maximize future reward and minimize future punishment at the same time, treating threat simply as minus value; as an animal experiences a cue with reward (or threat), a cue acquires positive (or negative) value that may induce approach (or avoidance). However, threat learning poses specific problems that differ from reward learning. While animals may learn from receiving actual rewards, animals usually cannot learn from the ultimate actual outcome of a potential threat such as its own death. Thus, threat avoidance is supported by various pre-programmed systems in the brain, and threat learning should integrate new information into those systems, rather than starting from scratch. Further, avoidance systems should not be too conservative to allow other activity. Sometimes, animals may have to overcome fear of a potential threat. Our lab is interested in the neural and computational mechanisms driving how animals estimate, learn and avoid potential threats at appropriate levels, balancing innate and learned information as well as reward and threat information.
Novelty exploration
Novelty exploration
Animals are curious about novelty, but are also sometimes afraid of it. How do animals decide whether to explore or to avoid? Although exploration is often modeled as a reward maximization problem, it is also a specific form of threat-coping. Animals want to expand their world (physical world or knowledge), but also need to avoid threat. Our lab is interested in the neural and computational mechanisms behind how animals balance curiosity and fear to explore.
Diversity and development of dopamine neurons
Diversity and development of dopamine neurons
We recently identified a unique subpopulation of dopamine neurons that project to the most posterior part of the striatum (tail of the striatum or TS). These dopamine neurons signal stimulus salience, and promote threat avoidance, in contrast to the general notion that dopamine neurons signal reward-related information and promote reward acquisition. Thus, our findings suggest multiple dopamine evaluation systems that may cooperate or even compete each other under reward-threat conflicts. We are currently studying the neural circuit and computational mechanism these dopamine neurons promote avoidance, as well as relationships with other dopamine systems in the adults and during development.
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