New York, Nov 25 (IANS): Various brain regions that once synchronised their activity during memory tasks become smaller and lose cohesion as people age, says a study.

In the study, researchers from Princeton University in New Jersey, US, described a novel method to characterise and compare the brain dynamics of individual people.

The research showed that regardless of whether we were using memory, directing attention, or resting, the number of synchronous groups of connections within our brain was consistent. 

However, between different individuals, these numbers vary dramatically.

In fact, during memory specific actions, variations between people are closely linked to age.

Younger participants have only a few large synchronous groups that link nearly the entire brain in coordinated activity, while older participants show progressively more but smaller groups of connections.

In the older group this indicates loss of cohesive brain activity -- even in the absence of memory impairment, the authors noted.

"This method elegantly captures important differences between individual brains, which are often complex and difficult to describe," said Elizabeth Davison from Princeton University. 

"The resulting tools show promise for understanding how different brain characteristics are related to behaviour, health, and disease," Davison added.

For the study, the researchers used functional magnetic resonance imaging (fMRI) to record healthy people's brain activity during memory tasks, attention tasks, and at rest. 

For each person, the fMRI data was recast as a network composed of brain regions and the connections between them. 

The scientists then use this network to measure how closely different groups of connections changed together over time.

The study was published in the journal PLOS Computational Biology.