Study reveals how hibernating mice retain memories despite massive synapse loss
Researchers found that mice undergoing artificial hibernation lose nearly half of hippocampal synapses but recover them and keep learned memories after two days.
A team led by Kazumasa Tanaka created an artificial hibernation model in mice and tracked brain changes with electron microscopy. During the dormant period, hippocampal activity fell by 70% and more than half of the synaptic connections vanished, contrary to expectations that larger spines would be preserved. After the mice awoke, over 80% of the missing dendritic spines reformed at their original sites, particularly within multisynaptic boutons that link one axon to several spines.
Mice tested on tasks involving food rewards and mild electric shocks retained those memories despite the structural upheaval. Experts not involved in the study, such as Michele Pignatelli and Cliff Abraham, highlighted the importance of these boutons and the surprising precision of synapse restoration. The findings challenge the notion that each memory-encoding synapse must persist, pointing instead to a broader network mechanism that protects recollection during extreme physiological states.
Why it matters
Understanding memory resilience during hibernation could inform treatments for brain injury and neurodegenerative diseases.
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