Portal de Periódicos da CAPES

Orchestrated ensemble activities constitute a hippocampal memory engram

2019; Nature Portfolio; Volume: 10; Issue: 1 Linguagem: Inglês

10.1038/s41467-019-10683-2

2041-1723

Khaled Ghandour, Noriaki Ohkawa, Chi Chung Alan Fung, Hirotaka Asai, Yoshito Saitoh, Takashi Takekawa, Reiko Okubo-Suzuki, Shingo Soya, Hirofumi Nishizono, Mina Matsuo, Makoto Osanai, Masaaki Sato, Masamichi Ohkura, Junichi Nakai, Yasunori Hayashi, Takeshi Sakurai, Takashi Kitamura, Tomoki Fukai, Kaoru Inokuchi,

Neural dynamics and brain function

Abstract The brain stores and recalls memories through a set of neurons, termed engram cells. However, it is unclear how these cells are organized to constitute a corresponding memory trace. We established a unique imaging system that combines Ca 2+ imaging and engram identification to extract the characteristics of engram activity by visualizing and discriminating between engram and non-engram cells. Here, we show that engram cells detected in the hippocampus display higher repetitive activity than non-engram cells during novel context learning. The total activity pattern of the engram cells during learning is stable across post-learning memory processing. Within a single engram population, we detected several sub-ensembles composed of neurons collectively activated during learning. Some sub-ensembles preferentially reappear during post-learning sleep, and these replayed sub-ensembles are more likely to be reactivated during retrieval. These results indicate that sub-ensembles represent distinct pieces of information, which are then orchestrated to constitute an entire memory.