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Oral Session

Learning and Cognition: Hippocampus


開催日 2016/7/21
時間 10:00 - 11:00
会場 Room H (304)
Chairperson(s) 林 康紀 / Yasunori Hayashi ( 国立研究開発法人理化学研究所 脳科学総合研究センター / RIKEN Brain Science Institute )
岡田 隆 / Takashi Okada (上智大学 総合人間科学部 心理学科 / Department of Psychology, Faculty of Human Sciences, Sophia University)
  • O2-H-2-2   Time: -

忘却とNMDA受容体: 獲得後のNVP-AAM077の長期的投与がその後の逆転課題に与える影響
Memory forgetting and NMDA receptor: Post-acquisition chronic microinfusion of NVP-AAM077 into dorsal hippocampus subsequently impairs the performance at spatial reversal task in Morris water maze

  • 篠原 恵介 / Keisuke Shinohara:1,2 畑 敏道 / Toshimichi Hata:3 
  • 1:同志社大院心理学 / Graduate School of Psychology, Doshisha University, Kyotanabe 2:日本学術振興会 / JSPS Research Fellow 3:同志社大心理 / Faculty of Psychology, Doshisha University 

Many studies had indicated the contribution of N-methyl-D-aspartate type glutamate receptors (NMDARs) to the memory acquisition. In contrast, several studies reported that blockade of NMDARs during retention interval following memory acquisition facilitates the retention of the previously acquired spatial memory. Recently, we demonstrated that the post-acquisition long-lasting infusion of a preferring NMDAR subunit GluN2A blocker NVP-AAM077 (NVP) by Alzet osmotic pumps also facilitates the spatial memory retention in rats. Additionally, the NVP-infused rats also exhibited the persistent behavior based on the obsolete information at the subsequent reversal test. In this study, however, rats were received a surgical operation after memory acquisition because the osmotic pumps cannot be manipulated the infusion schedules and replaced the containing solution. To minimize the injury events during retention interval, present study used an iPRECIO (SMP-200 model) for the chronic bilateral microinfusion into dorsal hippocampus. Following the implantation of iPRECIO and the recovery, rats were trained for four days (four trials per day) in the Morris water maze under the chronic infusion with saline. In this training the submerged escape platform was placed at the fixed position on the circular pool. The chronic microinfusion (1.0 μl per hour) of 0.1 mM NVP or vehicle solution (n = 4, each other) was prolonged from one day to six days after the end of training (Day 1-6). Following the end of drug infusion, rats were delivered the probe test (Day 7) and the reversal task (Day 8-9) under the chronic infusion of saline. In the reversal task the platform was placed at the opposite position to the original target. Although there was no significant difference between groups in their exploration at the probe test, the NVP-treated rats exhibited the longer escape latency and path length to reach the novel platform during the reversal task than controls did. Additionally, they explored around the original platform location longer than controls did. These results suggest that the chronic microinfusion of NVP after memory acquisition impairs the performances at the subsequent reversal learning task, consistent with our previous result. This impairment may be caused by the perseveration for the original memory. In conclusion, the activity of NMDAR subunit GluN2A downregulates the retention of the previously acquired memory.

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