教員の研究紹介
鈴木 章円

認知・情動脳科学専攻 Major of Cognitive and Emotional Neuroscience

セルアセンブリ活動変化と記憶の質的遷移の相関関係
Correlation between changes in cell assembly activity and qualitative transitions in memory
Akinobu Suzuki分子脳科学 Molecular brain science
鈴木 章円 Akinobu Suzuki

研究の背景と目的 Background and Purpose of Study

記憶は学習時に同期活動した神経細胞集団(セルアセンブリ)に保存され、そのセルアセンブリが再活動することで記憶が想起されます。しかし一言に記憶といっても多種多様で、一度の学習で形成される強い記憶もあれば、繰り返し学習することで徐々に強化される弱い記憶もあり、繰り返し学習による記憶の強化(質的遷移)とセルアセンブリの関係は明らかではありません。 一方、脳は課題遂行中だけでなく、休息時や睡眠時(=オフライン)にも活動しています。実際に、学習後に断眠すると記憶力が低下するといったことから、オフライン時の脳活動の記憶への重要性が示唆されています。さらに、記憶の形成には様々な脳領域が関わり、領域間での情報のやり取り(相互作用)が起こることも示唆されています。 これらの知見から、オフライン時のセルアセンブリ活動の「領域内変化」だけでなく「領域間相互作用」、2つの視点から研究を進めることが重要です。 本研究では、「繰り返し学習課題において、睡眠時にセルアセンブリ活動の領域内変化や領域間相互作用が誘導されることで、連合が促進し記憶が強化される」と仮説を立て、「多脳領域よりセルアセンブリ活動を捉え(多点イメージング)、同時に、それらの活動を操作する新規システム」を構築し、睡眠時のセルアセンブリ活動の領域内変化や領域間相互作用を計測・操作することで、記憶の質的遷移との相関関係を明らかにすることを目的としています。  
Memories are stored in neuronal populations (cell assemblies) that were synchronously activated during learning, and memories are recalled when those cell assemblies are reactivated. However, there are many different types of memories. Some memories are strong memories that are formed after a single learning experience, while others are weak memories that are gradually strengthened through repetitive learning. The relationship between cell assembly and the strengthening of memory through repetitive learning (qualitative transitions) is not clear. On the other hand, the brain is active not only during task performance (=online), but also during rest and sleep (= offline). In fact, previous studies suggested that sleep deprivation after learning impaired memory performance, indicating that the importance of brain activity during offline periods for memory. Furthermore, it has been suggested that various brain regions are involved in memory formation and that information exchange (interaction) occurs between regions. Based on these findings, it is important to study not only "intra-regional changes" in cell assembly activity during offline, but also "inter-regional interactions". In this study, we hypothesized that "intra-regional changes in cell assembly activity and inter-regional interactions induced during sleep enhance association and strengthen memory in repetitive learning tasks". To verify it, we are developing "a novel system to record cell assembly activity from multiple brain regions (multi-region imaging) and manipulate these activities at the same time and trying to clarify the correlation between these changes and qualitative transitions in memory.

参考文献

  • Suzuki A, Kosugi S, Murayama E, Sasakawa E, Ohkawa N, Konno A, Hirai H, Inokuchi K* A cortical cell ensemble in the posterior parietal cortex controls past experience-dependent memory updating. Nat Commun. ;13(1), 41, 2022
  • Yokose J, Okubo-Suzuki R, Nomoto M, Ohkawa N, Nishizono H, Suzuki A, Matsuo M, Tsujimura S, Takahashi Y, Nagase M, Watabe AM, Sasahara M, Kato F, Inokuchi K* Overlapping memory trace indispensable for linking, but not recalling, individual memories. Science. 355(6323), 398-403, 2017
  • Nomoto M, Ohkawa N, Nishizono H, Yokose J, Suzuki A, Matsuo M, Tsujimura S, Takahashi Y, Nagase M, Watabe AM, Kato F, Inokuchi K* Cellular tagging as a neural network mechanism for behavioural tagging. Nat Commun. 7:12319, 2016
  • Ohkawa N, Saitoh Y, Suzuki A, Tsujimura S, Murayama E, Kosugi S, Nishizono H, Matsuo M, Takahashi Y, Nagase M, Sugimura YK, Watabe AM, Kato F, Inokuchi K* Artificial association of pre-stored information to generate a qualitatively new memory. Cell Rep. 11(2), 261-9, 2015
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