Hibernation drastically reduces synaptic connections, yet mice retain learned memories despite this neural shift. Neuroscientist Kazumasa Tanaka explains that these brain links naturally change frequently, making long-term storage puzzling. To investigate, his team induced a controlled hibernation-like state, effectively altering more than half of existing synapses. Remarkably, cognitive performance stayed intact.

The method activates Q neurons in the hypothalamus, a mammalian circuit refined by collaborator Takeshi Sakurai. This protocol lowers body temperature to roughly 20° Celsius while slowing vital signs. Unlike wild hibernators, this artificial state switches on and off predictably.

After spending 48 hours in a deep metabolic slowdown, researchers tracked brain activity and used high-resolution imaging. Synaptic firing dropped significantly, and physical connections vanished. Despite fears of memory loss, trained mice flawlessly completed fear conditioning and navigation tasks after waking. These results demonstrate that consolidated memories persist even after severe synaptic pruning, challenging current models of how the brain preserves information long-term.