A new study says that a fatty acid in the brain, called palmitate, is what makes us memorize the stories which our grandmothers used to narrate to us.
The researchers have revealed how palmitate marks certain brain proteins - NMDA receptors - that need to be activated for long-term memory and learning to take place.
The fatty substance directs the receptors to specific locations in the outer membrane of brain cells, which continually strengthen and weaken their connections with each other, sculpting and resculpting new memory circuits.
In addition, the researchers said that the fatty modification is a reversible process, with some sort of on-off switch, offering possibilities for manipulating it to enhance or even, perhaps, erase memory.
"Before now, no one knew that NMDA receptors change in response to the addition of palmitate," said Dr. Richard Huganir at Johns Hopkins.
The study's results showed that the NMDA receptor undergoes "dual palmitoylation," in two different regions, each of which plays a distinct role in controlling the fate of the receptor in neurons.
When the fat attaches to the first region, it stabilizes the receptor on the surface of neurons. When the fat attaches to the second region, the receptors accumulate inside neurons, perhaps awaiting a signal to send them to synapses.
The researchers suspect that this could be part of a quality control measure, assuring that all the Lego-like protein subunits of the receptor are put together properly.
"It is rapidly becoming clear that palmitate regulates not only NMDA receptors, but also other brain proteins at work during signaling across synapses," said Dr. Gareth Thomas.
"This new modification of the NMDA receptor deepens our molecular understanding of how synapses are regulated and how memories might be formed. It also reveals new potential drug targets, such as the enzymes that add or remove the palmitate. If we could shift the balance of the palmitoylation, then perhaps we could affect and enhance learning and memory," said Huganir.
The study has been published in Neuron.