September 3, 2015
How your brain handles multitasking
By examining the brain’s various neural networks, a team of American and German researchers has shed new light on the neurological underpinnings of our ability to multitask, according to a new report in the Proceedings of the National Academy of Sciences.The study focused on processes in the brain's frontal cortex, an area linked with control over thoughts and decisions. The scientists revealed the degree to which frontal cortex networks reconfigure while alternating from task to task surmises people’s cognitive flexibility.
The study team said they focused on the interconnections between the networks indicated by synchronized activity, as opposed to examining a single region in the brain. Using fMRI to image the brain, the team can gauge which elements of the brain are “talking” to one another as their volunteers execute various tasks. This mapping of the neural network reconfigurations supplies a more holistic view of the way the brain functions.
"We tried to understand how dynamic flexibility of brain networks can predict cognitive flexibility, or the ability to switch from task to task," study author Danielle Bassett, a bioengineering expert at the University of Pennsylvania, said in a news release. "Rather than being driven by the activity of single brain areas, we believe executive function is a network-level process."
In an earlier study, Bassett and her colleagues found that those who could more rapidly “disconnect” their frontal cortices performed better on a task that involved pushing keys associated with color-coded notes on a screen. The high level decision-making linked with the frontal cortex wasn’t valuable in playing the brief sequences of notes for this study, so those who employed this part of the brain were basically overthinking a straightforward problem.
Reconfiguration only one step in switching tasks
In the new study, researchers had participants switch between a working memory task intended to engage the frontal cortex and a control task. The easy task included pushing the corresponding button as a series of numbers showed up on a screen one by one. The hard task also included a series of numbers on a screen, but volunteers had to press the button that corresponded to the number that showed up two places back in the series every time they saw a new one.
As participants performed their task, the team map how volunteers' brain activities changed during each part of the working memory task, each part of the control task, and parts in between where volunteers switched gears.
"The nodes in the network that are most involved in reconfigurations are cognitive control areas in the frontal cortex," Bassett said. "More flexibility within the frontal cortex meant more accuracy on the memory task, and more consistent connectivity between the frontal cortex and other regions was even more predictive."
The study team said their findings suggest reconfiguration is only one of many processes involved in successful task switching.
"It doesn't account for a huge amount variance," Bassett said, "but it suggests that this kind of reconfiguration is a fundamental aspect of cognitive flexibility."
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