Although scientists understand the mechanisms the brain uses to decide whether a given task is worth the effort, the influence of fatigue on this process is not yet well understood.

The researchers found that there were two different types of fatigue in distinct parts of the brain. The first type is experienced as a short-term feeling, which can be overcome after a short rest.
Whereas a second type is longer-term feeling that builds up, stops people from wanting to work, and doesn’t go away with short rests.

“We found that people’s willingness to exert effort fluctuated moment by moment, but gradually declined as they repeated a task over time,” says Tanja Muller, first author of the study, based at the University of Oxford.

The team tested 36 young, healthy people on a computer-based task, where they were asked to exert physical effort to obtain different amounts of monetary rewards.

The participants completed more than 200 trials and in each, they were asked if they would prefer to ‘work’ – which involved squeezing a grip force device – and gain the higher rewards offered, or to rest and only earn a small reward.

While performing the task, the participants also underwent an MRI scan, which enabled the researchers to look for activity in the brain that matched the predictions of the model.

They found that some areas of the brain had an activity that fluctuated in line with the predictions and another area showed how much fatigue was influencing people’s motivation to keep working.

This work provides new ways of studying and understanding fatigue, its effects on the brain, and how it can change some people’s motivation more than others.

Source: Medindia