Neuroimaging study maps the neural basis of multitasking.

Human multitasking is the apparent performance by an individual of handling more than one task, or activity, at the same time. Studies have shown that some people can be trained to multitask where changes in brain activity have been measured as improving performance of multiple tasks. A very rich background of studies show that multitasking can also be assisted with coordination techniques, such as taking notes periodically, or logging current status during an interruption to help resume a prior task midway.

As the brain cannot fully focus when multitasking, people take longer to complete tasks and are predisposed to error. When people attempt to complete many tasks at one time, errors go way up and it takes far longer. This is largely because the brain is compelled to restart and refocus with studies showing that in the interim between each exchange, the brain makes no progress whatsoever. Therefore, multitasking people perform each task less suitably and lose time in the process.  However, this doesn’t explain previous studies that show people being trained to- or in high-pressured positions who are able to perform and multi-task in their jobs to a point of excellence.

Now, a study from researchers at the University of Pennsylvania, Central Institute of Mental Health and Charité University has shown using brain scans how neural networks reconfigure themselves while switching from task to task, otherwise known as multitasking.  The new study shows that the degree to which these networks reconfigure themselves while switching from task to task predicts people’s cognitive flexibility.  The team state that a more fundamental understanding of how the brain manages multitasking could lead to better interventions for medical conditions associated with reduced executive function, such as autism, schizophrenia or dementia.  The opensource study is published in the journal Proceedings of the National Academy of Sciences.

An earlier study from the team showed that people who could more quickly ‘disconnect’ their frontal cortices did better on a task that involved pressing keys that corresponded to color-coded notes on a screen. The high level decision-making associated with the frontal cortex’s cognitive control wasn’t as critical to playing the short sequences of notes, so those who still engaged this part of the brain were essentially overthinking a simple problem.  Rather than looking at the role a single region in the brain plays, the lab study the interconnections between the regions as indicated by synchronized activity.

In the current study 344 participants alternated between a working memory task designed to engage the frontal cortex and a control task. The easy task involved pressing the corresponding button as a sequence of numbers appeared on a screen one by one. The hard task also involved a sequence of numbers on a screen with participants having to press the button that corresponded to the number that appeared two places back in the series each time they saw a new one.

The lab scanned networks of activity in the brain’s frontal cortex, a region associated with control over thoughts and actions.  Using fMRI, the researchers measured which parts of the brain were ‘talking’ to one another as the participants performed various tasks. The group explain that mapping the way this activity network reconfigures itself provides a more holistic view of how the brain operates.  Results show that participants who performed best while alternating between a memory test and a control test showed the most rearrangement of connections within their frontal cortices as well as the most new connections with other areas of their brain.

Data findings show that the nodes in the network that are most involved in reconfigurations are cognitive control areas in the frontal cortex.  In this way the group state they can begin to understand how dynamic flexibility of brain networks can predict cognitive flexibility, or the ability to switch from task to task. Rather than being driven by the activity of single brain areas, they state executive function is a network-level process.

The team surmise that this suggests 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 lab conclude that while the predictive strength of this reconfiguration suggests that it is only one of several processes involved in successful task switching, it plays a core role.

Source: University of Pennsylvania


Evolving network organization. A mapping of the frontal modules obtained in B to their brain coordinates for the 0-back (Left) and 2-back condition (Right); labels are as in C. Dynamic reconfiguration of frontal brain networks during executive cognition in humans. Bassett et al 2015.

Evolving network organization. A mapping of the frontal modules obtained in B to their brain coordinates for the 0-back (Left) and 2-back condition (Right); labels are as in C. Dynamic reconfiguration of frontal brain networks during executive cognition in humans. Bassett et al 2015.

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