Our brain can only store a finite amount of information. Hence, it is just as important for us to forget trivial details as it is to remember important ones. Removing unnecessary memories allows our brain to continuously collect new, useful information.
Researchers recently learned that cells called microglia play a role in determining which memory is kept and which is forgotten. These cells remove synapses— structures in the nervous system that allow transmission of information from one nerve cell to another—and in the process cause memories linked to these synapses to be lost.
This discovery could be important in the search for a treatment for Alzheimer’s disease, as synapse destruction is linked to this disease. Who knows, it may also one day allow us to have a means to remove traumatic memories from our mind—something that could be useful in treating people with post-traumatic stress
Reference: Wang, C., et al. (2020). Microglia mediate forgetting via complement-dependent synaptic elimination. Science;367(6478):688–694.