Memories are made of synaptic regulators, new research reveals
The octogenarian grandmother who possesses a “mind like a razor” may not necessarily owe her mental abilities to a youthful brain, scientists believe.
Instead she may have by-passed the expected declines of ageing by switching to a different memory mechanism.
The discovery could lead to the development of new preventative treatments and therapies based on how healthily old brains function.
So far, research into improving mental ability in old age has looked at a younger brain model which may not be so relevant.
Although the findings emerged from studies of rats, scientists believe they probably apply to humans too.
Researcher Dr Michela Gallagher, from Johns Hopkins University in Baltimore, Maryland, USA, said: “We found that aged rats with preserved cognitive abilities are not biologically equivalent to young rats in some of the basic machinery that neurons use to encode and store information in the brain.”
Dr Gallagher’s team compared the brains of six-month-old rats with those of “aged” two-year-old rodents that performed as well as young animals when given a range of learning tasks.
The aged rats’ brains were also compared with those of other older rats which showed a loss of learning ability.
The scientists focused on a key set of nerve connections that store information by modifying the strength of chemical communications at the synapses - tiny gaps between adjoining nerve cells.
Messages are passed across the synaptic gap by neurotransmitter chemicals secreted by neurons. A chemical is released by one cell and acts on another to complete the circuit.
Synaptic communication is known to be at the heart of the way brains register and preserve information from memories.
The new findings, published today in the journal Nature Neuroscience, showed that older rats with impaired memory had lost the ability to adjust the force of these connections.
Older rats whose memories remained sharp maintained this capacity. But often they switched to a synaptic regulator different from the one normally used for memory storage at a younger stage of life.
“Instead, successful agers relied more than young rats on a different mechanism for bringing about synaptic change,” said Dr Gallagher.
“This ‘switch’ could serve the same purpose - storing memories - but through a different neurochemical device.”
The researchers wrote in the journal: “We propose that this type of uncoupling has consequences for preventing cognitive decline with age. It will be of future interest to test this possibility.”
