US scientists believe they have uncovered one of the mechanisms that enables the brain to form memories.
Synapses - where brain cells connect with each other - have long been known to be the key site of information exchange and storage in the brain.
But researchers say they have now learnt how molecules at the site of the synapse behave to cement a memory.
It is hoped the research, published in Neuron, could aid the development of drugs for diseases like Alzheimer's.
The deteriorating health of the synapses is increasingly thought to be a feature of Alzheimer's, a disease in which short-term memory suffers before long-term recollections are affected.
A strong synapse is needed for cementing a memory, and this process involves making new proteins. But how exactly the body controls this process has not been clear.
Now scientists at the University of California Santa Barbara say their laboratory work on rats shows the production of proteins needed to cement memories can only happen when the RNA - the collection of molecules that take genetic messages from the nucleus to the rest of the cell - is switched on.
Until it is required, the RNA is paralysed by a "silencing" molecule - which itself contains proteins.
When an external signal comes in - for example when one sees something interesting or has an unusual experience - the silencing molecule fragments and the RNA is released.
Kenneth Kosik of the university's neuroscience research institute said: "One reason why this is interesting is that scientists have been perplexed for some time as to why, when synapses are strengthened, you have the degradation of proteins going on side by side with the synthesis of new proteins.
"So we have now resolved this paradox. We show that protein degradation and synthesis go hand in hand. The degradation permits the synthesis."
Identifying the proteins the brain needs in order to cement the memory could ultimately have benefits for those suffering from memory disorders.
Rebecca Wood, head of the Alzheimer's Research Trust, said: "Scientists say they have studied nerve cells in the laboratory and learnt more about how specific proteins may have a role in areas of the brain that transmit messages and help us store memories.
"This interesting development could give a greater understanding of the memory loss experienced by people with Alzheimer's and other forms of dementia and lead to new treatments."
The most recent projections suggest 115 million people across the globe will suffer from dementia by 2050.
Julie Williams, professor of psychological medicine at Cardiff University, said: "Our increasing understanding of genetic risk factors in Alzheimer's is pointing to the synapses so any new study in this area is welcome.
"Alzheimer's is a complicated disease and it is early days, but the health of synapses and their activity levels is becoming an important and interesting focus of research."