Researchers find clues to how the brain decides when to rest

January 22, 2013 by Bob Yirka, Medical Xpress report
Task. The illustrated screenshots were successively presented every trial. When the thermometer image was displayed, participants had to squeeze a handgrip to win as much money as possible. Credit: (c) PNAS, DOI: 10.1073/pnas.1211925110

(Medical Xpress)—A team of researchers in France has found what they call a "signal" that tells a person when to rest while engaging in work, and then when to resume once rested. The team, as they describe in their paper published in the Proceedings of the National Academy of Sciences, used fMRI scans on a group of volunteers to study a part of the brain normally associated with pain perception and found what amounts to a signal calling for the conscious mind to take a break.

Scientists studying how people make decisions regarding work have over time devised theories of cost versus benefit scenarios to describe what causes people to engage in work activities, or to not. Not so well studied is how people come to decide when it's time to take a break. Some have suggested that some part of the brain is constantly engaged in weighing the costs of the work involved with potential rewards, and based on both creates a signal of sorts alerting the rest of the brain to when it's time to pause. This new research supports that theory.

The researchers enlisted the aid of 39 participants who were asked to squeeze a spring-loaded handgrip over and over as they underwent fMRI scans. Each was promised a monetary reward for doing so based on a sliding scale. The longer they squeezed, the better the reward would be.

In analyzing the fMRI images, the researchers discovered that activity in a called the posterior insula (normally associated with ), built over time as the continued squeezing – a signal of sorts. It grew during effort, and then faded during rest times – peaking just before resting. The researchers suggest that when a certain peak is reached, the rest of the brain is alerted to the need to take a break. The team also found that increasing the difficulty of the squeezing led to the signal increasing at a faster rate, but slowed when a bigger reward was offered despite the increased . They also found that bumping up the reward during a rest period caused the lowest signal point to come more quickly, indicating that rest time was up sooner than it would have been otherwise.

The researchers suggest that their observations indicate that they brain is constantly engaged in a struggle to maximize reward, while simultaneously minimizing the amount of work needed to get that , and uses rests stops to help it get there in a manner best suited to the work at hand.

Explore further: How humans predict other's decisions

More information: "A neuro-computational account of how the human brain decides when to have a break," by Florent Meyniel et al. PNAS, 2013. www.pnas.org/cgi/doi/10.1073/pnas.1211925110

Abstract
No pain, no gain: cost–benefit trade-off has been formalized in classical decision theory to account for how we choose whether to engage effort. However, how the brain decides when to have breaks in the course of effort production remains poorly understood. We propose that decisions to cease and resume work are triggered by a cost evidence accumulation signal reaching upper and lower bounds, respectively. We developed a task in which participants are free to exert a physical effort knowing that their payoff would be proportional to their effort duration. Functional MRI and magnetoencephalography recordings conjointly revealed that the theoretical cost evidence accumulation signal was expressed in proprioceptive regions (bilateral posterior insula). Furthermore, the slopes and bounds of the accumulation process were adapted to the difficulty of the task and the money at stake. Cost evidence accumulation might therefore provide a dynamical mechanistic account of how the human brain maximizes benefits while preventing exhaustion.

Related Stories

How humans predict other's decisions

June 20, 2012
Researchers at the RIKEN Brain Science Institute (BSI) in Japan have uncovered two brain signals in the human prefrontal cortex involved in how humans predict the decisions of other people. Their results suggest that the ...

In the brain, winning is everywhere

October 5, 2011
Winning may not be the only thing, but the human brain devotes a lot of resources to the outcome of games, a new study by Yale researchers suggest.

Research shows brain hub activity different in coma patients

November 27, 2012
(Medical Xpress)—A team of French and British researchers has found that brain region activity for coma patients is markedly different than for healthy people. In their paper published in the Proceedings of the National ...

Study links hippocampus with unconscious bias

October 12, 2012
(Medical Xpress)—A new US study into brain function has found links between preferences and the regions of the brain involved in connecting new memories to old ones. The associations formed provide shortcuts the subconscious ...

Recommended for you

Brain zaps may help curb tics of Tourette syndrome

January 16, 2018
Electric zaps can help rewire the brains of Tourette syndrome patients, effectively reducing their uncontrollable vocal and motor tics, a new study shows.

A 'touching sight': How babies' brains process touch builds foundations for learning

January 16, 2018
Touch is the first of the five senses to develop, yet scientists know far less about the baby's brain response to touch than to, say, the sight of mom's face, or the sound of her voice.

Researchers identify protein involved in cocaine addiction

January 16, 2018
Mount Sinai researchers have identified a protein produced by the immune system—granulocyte-colony stimulating factor (G-CSF)—that could be responsible for the development of cocaine addiction.

Neuroscientists suggest a model for how we gain volitional control of what we hold in our minds

January 16, 2018
Working memory is a sort of "mental sketchpad" that allows you to accomplish everyday tasks such as calling in your hungry family's takeout order and finding the bathroom you were just told "will be the third door on the ...

Brain imaging predicts language learning in deaf children

January 15, 2018
In a new international collaborative study between The Chinese University of Hong Kong and Ann & Robert H. Lurie Children's Hospital of Chicago, researchers created a machine learning algorithm that uses brain scans to predict ...

Preterm babies may suffer setbacks in auditory brain development, speech

January 15, 2018
Preterm babies born early in the third trimester of pregnancy are likely to experience delays in the development of the auditory cortex, a brain region essential to hearing and understanding sound, a new study reveals. Such ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.