Brain ‘network maps’ reveal clue to mental decline in old age

WASHINGTON - An Australian study has revealed that the human brain operates as a highly interconnected small-world network - and not as a collection of discrete regions as previously believed - with important implications for why many of us experience cognitive declines in old age.

Perminder Sachdev of University of New South Wales and colleagues have mapped human brain’s neural networks and linked them to specific cognitive functions such as information processing and language.

They are now examining what factors may influence the efficiency of these networks in the hope that they can be manipulated to reduce age-related decline.

“While particular brain regions are important for specific functions, the capacity of information flow within and between regions is also crucial. We all know what happens when road or phone networks get clogged or interrupted,” said Sachdev.

“It’s much the same in the brain. With age, the brain network deteriorates and this leads to slowing of the speed of information processing, which has the potential to impact on other cognitive functions,” he said.

Sachdev said that the advent of new MRI technology and increased computational power had allowed the development of the neural maps, resulting in a paradigm shift in the way scientists view the brain.

In the study, the researchers performed magnetic resonance imaging (MRI) scans on 342 healthy individuals aged 72 to 92, using a new imaging technique called diffusion tensor imaging (DTI).

Using a mathematical technique called graph theory, they plotted and measured the properties of the neural connectivity they observed.

“We found that the efficiency of the whole brain network of cortical fibre connections had an influence on processing speed, visuospatial function - the ability to navigate in space - and executive function,” said study first author Wei Wen.

“In particular greater processing speed was significantly correlated with better connectivity of nearly all the cortical regions of the brain,” he added.

Sachdev said the findings help explain how cognitive functions are organised in the brain, and the more highly distributed nature of some functions over others.

The study is published in Neuroscience. (ANI)