Scientists Try To Find What Happens When Our Brains Forget
When Cesare Pavese said that we do not remember days, but remember moments, he may be romanticizing it quite a bit: we know that memories change over time, and dementia and Alzheimer's disease make people forget even the dearest memories they hold.
People forget, but what happens to the memories that lose their way? Do they just disappear from the brain? Do they become blank space that act as black holes where information is doomed to disappear forever?
Computational neuroscientist Paul King had the answer. As he shared on Quora, the memories are stored as a kind of chemical change that connects points between neurons. There are about 100 trillion synapses in the human brain, and each of our memories are stores as slight changes to these synapses. With this in mind, memories actually have a "distributed" representation as each one involves thousands of synapses, and each of these synapse are part of possibly thousands of memories.
Long-term memories that survive at least the next day are resulted in what could possibly be permanent change to thousands of these synapses. In a study published in the journal Nature, it was found that the activity of the individual neurons in the hippocampus - or memory region - is note set in a single neuron, but in thousands of neurons that retrieve images of faces or associations.
Recalling life events, meanwhile, is a process of reconstruction, so memories degrade, while similar memories merge. These clusters can become disconnected islands and appear "forgotten" until something that can be associated with the memory is connected to the island and can bring back a whole world.
As Medical Daily put it, reconstructing forgotten memories is similar to archaeologists trying to rebuild the city of Troy: at some point, the brain's ability to recover one's memories can be obliterated permanently - but if you're lucky enough, the memories could remain dormant, just waiting for the right experiences to recreate the story that you forgot you knew.