Response and function of hippocampus against delay

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K15196
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Environmental physiology(including physical medicine and nutritional physiology)
• Research Institution: Doshisha University (2017-2018); Institute of Physical and Chemical Research (2016)
• Principal Investigator: Masuda Akira 同志社大学, 研究開発推進機構, 助教 (30612121)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 海馬 / 遅延 / 時間割引 / 意思決定 / 衝動性 / 電気生理学 / NMDA受容体 / マウス

Outline of Final Research Achievements

We electrophysiologically recorded the hippocampal CA1 activity during a delay after which rewards are delivered. Gradual extension of the delay length impacted on the firing rate of CA1 neurons. There was subpopulation of neurons which were activated or suppressed during a delay. Manipulation of reward size also impacted on the firing rate of CA1 neurons. Notably, the subpopulations exhibited a distinct trend of firing rate change after reward size manipulation. This suggests that information of delay and reward is not separately encoded in the hippocampus. Moreover, genetic deletion of NMDA receptor in the hippocampus led suppression of impulsive choices and abnormal response characteristics against delay, suggesting a control system mediated by NMDA receptors.

Free Research Field

神経科学

Academic Significance and Societal Importance of the Research Achievements

本研究は海馬の時間的情報処理に関して新たな一面を明らかにしたといえる。さらに現在、報酬に対する情報処理や目的志向性行動に関する海馬の役割が注目されており、本研究はその概念の明確化の一助にもなると思われる。
また、研究成果の一部は衝動性を制御するのが困難な注意欠陥多動性症候群や痴呆性の衝動性行動、発達障害者の固執性行動、強迫性行動などの症状制御に新たな対処策を提案する一助になる可能性を持つと思われる。