Cognitive and learning psychological studies on circadian rhythm in the memory system

2014 Fiscal Year Final Research Report

• Project/Area Number: 24530922
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Experimental psychology
• Research Institution: Sophia University
• Principal Investigator: OKADA Takashi 上智大学, 総合人間科学部, 教授 (00242082)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 海馬 / ラット / メラトニン / 新奇物体再認課題 / 新奇位置再認課題 / 概日リズム / 長期抑圧 / グルタミン酸受容体

Outline of Final Research Achievements

The diurnal variation of performance in hippocampus-dependent learning tasks in rats and the effect of the pineal hormone melatonin on such performance were examined. Rats were subjected to the novel object recognition (NOR) task or the novel location recognition (NLR) task at either of four time zones of the day; the results showed that the performance was higher at night than during the daytime. When melatonin was injected into rats before the training phase of the NLR task, they showed improvement of performance in the daytime, but impairment at night, suggesting that melatonin within a certain concentration range may act to promote memory performance. Using rat hippocampal slice preparations, the effects of melatonin on the long-term depression (LTD) of CA1 synaptic responses were examined; the results showed that NMDA receptor-dependent LTD was promoted by melatonin, but metabotropic glutamate receptor-dependent LTD was not regulated by it.

Free Research Field

生理心理学