Neuronal and synaptic mechanisms of smart fogeting by sleep/wake cycles

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K15204
• 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: University of Toyama
• Principal Investigator: Miyamoto Daisuke 富山大学, 学術研究部医学系, 准教授 (50748697)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 睡眠 / 記憶 / 神経細胞 / シナプス / イメージング / 光遺伝学 / マウス / 受容体

Outline of Final Research Achievements

Sleep reorganizes synapses and acts on both memory consolidation and forgetting. Since previous studies evaluated the average synaptic dynamics, the sleep dynamics of synapses responsible for memory were unknown. Therefore, the present study was conducted by temporal fluorescence imaging of individual neurons and spines in the cerebral cortex of living mice. Spines with increased AMPA receptor levels during learning were unaffected by post-learning sleep, whereas other spines showed decreased AMPA receptor levels during sleep. It is suggested that synaptic plasticity due to post-learning sleep weakens the average synaptic strength but allows the retention of the immediately preceding learning information, resulting in smart fogging. In order to measure neural activity through learning and sleep over a long period of time, we constructed an imaging system for single neuron resolution under free-running and head immobilization conditions.

Free Research Field

行動神経生理学

Academic Significance and Societal Importance of the Research Achievements

成体脳の神経細胞数は殆ど増加しないため、脳は記憶容量を節約しながら学習する必要がある。そこで、本研究は生きたマウスの脳を顕微鏡観察して、記憶を担う個々のシナプスの強度を経時的に定量した。睡眠は学習により増強したシナプスを保護しながら、その他のシナプスを弱めることが分かった。睡眠は直前の学習情報を保ちながら、シナプスをクールダウンさせて記憶容量を回復させる役割があると考えられる。