Kazumasa Tanaka: Neural State Transitions Reveal Fundamental Principles of Memory Stability and Circuit Reset

Okinawa Institute of Science and Technology Graduate University, Memory Research Unit

Title:  Neural State Transitions Reveal Fundamental Principles of Memory Stability and Circuit Reset

Abstract:

The brain continuously changes. Synapses are formed, eliminated, and remodeled throughout life, yet memories can persist for years. This apparent contradiction raises a fundamental question: what exactly is stable in a memory trace?

To address this problem, we developed a mouse model of artificial hibernation in which activation of hypothalamic Q neurons induces prolonged hypothermia and hypometabolism. During this hibernation-like state, hippocampal activity is profoundly suppressed and synapses are eliminated on a massive scale. Nevertheless, animals retain previously formed memories, and hippocampal spatial representations recover with remarkable fidelity after arousal.

These findings challenge the idea that long-term memories require static preservation of specific synaptic structures. Instead, our data suggest that memory engrams possess a flexible and adaptive architecture capable of surviving extensive circuit remodeling. I will discuss evidence from electrophysiology, calcium imaging, and electron microscopy indicating that endogenous state transitions recruit coordinated programs that preserve functional organization despite structural disruption.

Finally, I will present ongoing work showing that the same state transitions can suppress pathological network dynamics during epileptogenesis, supporting the broader idea that the brain contains intrinsic reset mechanisms capable of reorganizing neural circuits while preserving essential computational structure.

Artificial hibernation thus offers not only a potential therapeutic strategy, but also a powerful conceptual tool for uncovering fundamental principles of memory persistence and neural circuit stability.

 

Guests are welcome!

 

Organized by

Matthias Haberl / Lisa Rosenbluhm