Formation mechanism and functional role of place cell ensemble related to reward-associated memory

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K16293
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 46030:Function of nervous system-related
• Research Institution: Kyoto University
• Principal Investigator: Kotaro Mizuta 京都大学, 医学研究科, 助教 (60632891)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 報酬 / 記憶 / バーチャルリアリティ / 二光子イメージング / 場所細胞 / 海馬

Outline of Final Research Achievements

Place cells around reward in the hippocampus are more numerous and stable than in other locations, and we named them “reward place cells”. We aimed to elucidate functional role and formation mechanism of reward place cells. For the purpose, we visualized hippocampal neural activity in mice navigating virtual reality linear track tasks using two-photon microscopy. If the reward location could not be identified by changing randomly every trial, over-representation of reward place cells was not observed. Next, mice performed a delayed task in which the reward was given if mouse stay at the reward location for 2 seconds. A subset of reward place cells was active during stopping in the reward location. Thus, reward place cells were either associated with anticipation of reward or with recognition of the reward location. We found that the reward relocations cause the rapid formation of reward place cells by reorganization from existing cognitive maps, unlike novel learning.

Free Research Field

神経科学

Academic Significance and Societal Importance of the Research Achievements

探索経路の記憶には静止時に場所細胞群が高速で発火するreplay現象が関与するが、探索経路で報酬のような重要な目的地が場所細胞やその他の細胞によってどのように表現され記憶されるかわかっていなかった。本研究で明らかになった報酬の周辺の場所細胞や報酬事象を示す細胞の特性、それらの活動およびダイナミクスなどの知見は、行動に関連する海馬の神経回路ダイナミクスやシナプス可塑性、および、アルツハイマー病のような記憶研究に関わる病態モデル、人工知能研究などの多くの研究分野に大きなインパクトをもたらすことが期待される。