Wie sich emotionale Erinnerungen mit überraschenden Helferzellen ins Gehirn einprägen

>Nagai and his colleagues focused on the question of memory stabilization: how a short-term memory becomes more permanent in the brain. Previous research had found physical traces of memories in neuronal networks in brain regions such as the hippocampus and amygdala[^(2)](https://www.nature.com/articles/d41586-025-03366-0#ref-CR2). But it was unclear how these ‘engrams’ were stored in the brain as lasting memories after repeated exposure to the same stimulus.

>In a well-established fear-conditioning memory task, mice learnt to associate a certain cage with unpleasant shocks to their feet while the researchers tracked the level of *Fos* in their brains. Days later, the animals would re-enter the cage and recall the unpleasant sensation. The researchers observed strong *Fos* upregulation in astrocytes in the animals’ amygdalas and other brain regions when mice re-entered the cage, but not during the initial learning phase, suggesting that astrocyte activity was more important for recalling past events than creating new memories.

>**“The surprise was that astrocytes did not respond to the fear experience the first time, only the second time,”** says Nagai.

rest is behind paywall, but this last line is very intriguing