How Brain Performs Tough Tasks Decoded

Some people may be better at performing complex tasks as the coordination between different parts of their brains seem to ebb and flow, rather than being static, scientists have found.

According to researchers at Stanford University in the US these fluctuating patterns may explain why some people learn new tasks more quickly.

Analysing the brains at rest and carrying out complex tasks, researchers found that the integration between brain regions also fluctuates.

They used data from the Human Connectome Project to examine how separate areas of the brain coordinate their activity over time, both while people are at rest and while they are attempting a challenging mental task.

For the resting state condition, the researchers used a novel analysis technique to examine functional magnetic resonance imaging (fMRI) data - which shows in real time which areas of the brain are active - of people who were not doing any particular task.

The analysis estimates the amount of blood flow in pairs of brain regions and then uses the mathematics of graph theory to summarise the way that the whole network of the brain is organised.

Researchers found that even without any intentional stimulation, the brain network fluctuates between periods of higher and lower coordinated blood flow in the different areas of the brain.

To determine whether these fluctuations were relevant for the function of the brain, they used fMRI data from people who had successfully performed a challenging memory test. Researchers found that the brains of participants were more integrated while working on this complicated task than they were during quiet rest.

"This research shows these really clear relationships between how the brain is functioning at a network level and how the person's actually performing on these psychological tasks," said Russell Poldrack, a professor at Stanford.

Researchers also measured pupil size to try and tease out how the brain coordinates this change in connectivity.

Pupil size is an indirect measure of the activity of a small region in the brainstem called the locus coeruleus that is thought to amplify or mute signals across the entire brain.

Up to a certain point, increases in pupil size likely indicate greater amplification of strong signals and greater muting of weak signals across the brain.

Researchers found that pupil size roughly tracked with changes in brain connectivity during rest, in that larger pupils were associated with greater connectedness.

This suggests that the noradrenaline coming from the locus coeruleus might be what drives the brain to become more integrated during highly complicated cognitive tasks, allowing a person to perform well on that task.

The research appears in the journal Neuron.