Fatigue can make it difficult to carry on with our everyday lives and function normally. Work, school, exercise, and stress when compounded together can result in fatigue and the feeling of being sluggish or groggy. However, there is more research that needs to be conducted to fully understand how fatigue influences behavior. Consequently, researchers from Johns Hopkins University School of Medicine just published a study on how the brain processes fatigue and the mechanisms involved in this processing.
In this study, researchers used functional magnetic resonance imaging (fMRI), which detects changes in blood flow in the brain, to image participants’ brain activity. These scans were done while the participants made decisions on exerting physical effort for an activity. Over time, their physical activity introduced fatigue as muscles tired out. The study members were trained to squeeze a sensor that measured the amount of effort exerted in the physical activity. This enabled the researchers to avoid using subjective pain scales to rank activity, as that has the ability to introduce bias into the study. The participants then went through a series of trials in which they squeezed the sensor to show the effort they would display in the situation to introduce fatigue. Once in a fatigued state, they were asked further questions to analyze the risks they would take in various situations.
An example of an MRI scan that is able to identify regions of the brain that are activated when participants make risk-based decisions in a fatigued state.
Image Source: Andrew Brookes
From these experiments, the researchers were able to conclude that in a state of fatigue, people chose to avoid riskier situations and tasks requiring greater effort. Since the participants’ brains were being scanned during these trials, the researchers could determine which regions of the brain were activated in response to fatigue and when making risk-based decisions. Across the participants, the researchers discovered that the insula was consistently activated. The insula is a region in the cerebral cortex of the brain that makes survival-based decisions. They also discovered that the motor cortex, which is responsible for stimulating muscles to move and flex, is not activated when people made their decision on their level of physical effort. This finding shows that in a fatigued state, the cerebral cortex influences decision-making in order to prevent people from engaging in activities they are not physically able to complete. These novel findings help to identify the regions of the brain that are involved in fatigue and how decision-making is regulated in a fatigued state.
This information can be useful and translatable for therapeutic efforts that help people who deal with chronic fatigue. With further research, it might be possible to not drink 3 cups of coffee to feel ready for the day!
Featured Image Source: Sammy-Williams
