psydoctor8:

MIT neuroscientists explain ‘Proustian effect’ of small details attached to big memories

Previous research has focused on the role of synapses—the connections through which neurons communicate. An individual synapse is thought to be the minimum unit necessary to establish a memory engram. 

 The MIT researchers found that a memory of a seemingly irrelevant detail — the kind of detail that would normally be relegated to a short-term memory — may accompany a long-term memory if two synapses on a single dendritic arbor are stimulated within an hour and a half of each other.

It’s about the timing and strength of the signals that determine a short v. long term memory.

This occurs because the weakly stimulated synapse can steal or hitchhike on a set of proteins synthesised at or near the strongly stimulated synapse. These proteins are necessary for the enlargement of a dendritic spine that allows the establishment of a long-term memory.

“Not all irrelevant information is recalled, because some of it did not stimulate the synapses of the dendritic branch that happens to contain the strongly stimulated synapse,” Israely said.