Specialistpainphysio: CBC News - Health - Brain wiring key to quick decisions: study

The ability to make quick decisions when they are needed depends on whether your brain connections are the neural equivalent of broadband or dial-up, an international study shows.

In a Proceedings of the National Academy of Sciences paper released online Tuesday, an international team shows flexibility in decision-making is dependent on structural features of the brain.

'As you get older, the bandwidth gets slower and slower.'— Scott Brown

Quick decisions tend to be error-prone while relatively slower contemplation tends to produce more accuracy, says one Australian research team member, Scott Brown, an associate professor at the University of Newcastle's cognition laboratory.

This trade-off between speed and accuracy means people need to be able to switch between the fast risky and slower cautious modes of decision-making, as required.

But, says Brown, little is known about the neurology underpinning this flexibility.

Broadband or dial-up?

In their study, Brown and colleagues, which included researchers from the United Kingdom, Germany and the Netherlands, examined what brain mechanisms underpin decision-making flexibility.

They found it was determined by the "purely physical measurement" of the thickness of the connections between the brain's cortex and the striatum of the basal ganglia.

He says the results are the equivalent of brain communication being reliant on a broadband connection or still using dial-up.

"The underlying finding that a purely physical measurement could predict behaviour is very surprising," he says.

Brown says the team has not determined what causes one person's connections to be thicker than another's.

"It could be that it is the 'use it or lose it'" phenomenon, he says.

However, in a paper still under review, Brown says, the team has also shown the connection thins with age.

"As you get older, the bandwidth gets slower and slower," he says.

MRI scans measure fibre thickness

For the study, participants were placed in an MRI scanner and the researchers measured the thickness of "fibres" that carry inputs from the cortex to the basal ganglia.

Brown says the technology allows researchers to "track millimetre by millimetre which direction fibres in the grey matter are travelling," and determine the number (or thickness) of fibres connecting one region to another.

These measurements were done when the participants were not making decisions. They were also required to undertake a series of tasks that required them to make decisions either quickly or slowly.

They found those with the stronger connections in the brain were more able to move flexibly between a fast response and a more accurate slow response.

The study was based on only nine participants, however, the researchers used a previous independent study, which had included MRI scans, to verify their findings.

'Train the brain'

Brown says their work could help in tracking cognitive decline in aging.

"People who have a disease of aging often have their symptoms exacerbated by the slowing that comes with aging," he says.

"If you can understand the slowing, we might be able to separate the effects and better understand what is happening."

He says there is a view that older people are slow and cautious because they choose to be so.

However, these latest findings would suggest that as brain connections thin, the person is "stuck in a regime where response is always slow and cautious."

In current work, Brown says they are trying to force older participants to be faster at decision-making.

"We are seeing if you can train the brain to use these tracks more efficiently," he says.

© Australian Broadcasting Corporation, 2010