How brain keeps memories alive for decades

Washington: An Indian-origin researcher- led team of scientists claims to have found a vital clue as to how long-term memories are formed in brain, which may pave the way for better understanding of diseases like Alzheimer`s.

It`s known that memories in our brains are maintained by connections between neurons called "synapses".

Now, Amitabha Majumdar and colleagues at the Stowers Institute for Medical Research claim to have discovered from a research in fruit flies about how do these synapses stay strong and help keep memories alive for decades.

Their research has revealed that it`s the hardy, self-copying clusters or oligomers of a synapse protein that help in the formation of long-term memory, the `Cell` journal reported in its latest edition.

"Self-sustaining populations of oligomers located at synapses may be the key to the long-term synaptic changes that underlie memory; in fact, our finding hints that oligomers play a wider role in the brain than has been thought," said Kausik Si, one of the team`s members.

In their research, the scientists analysed a Drosophila fruit fly CPEB protein known as Orb2. Like its counterpart in Aplysia, it forms oligomers within neurons.

"We found that these Orb2 oligomers become more numerous in neurons whose synapses are stimulated, and this increase in oligomers happens near synapses," said Majumdar.

The scientists say that the key was to show that the disruption of Orb2 oligomerization on its own impairs Orb2`s function in stabilising memory. They did this by generating an Orb2 mutant that lacks the normal ability to oligomerize yet maintains a near-normal concentration in neurons.

Fruit flies carrying this mutant form of Orb2 lost their ability to form long-term memories, the research found.

"For the first 24 hours after a memory-forming stimulus, the memory was there, but by 48 hours it was gone, whereas in flies with normal Orb2 the memory persisted," Majumdar said, adding that the finding may help understand disease-causing oligomers involved in Alzheimer`s.