CHEARS

Scientists at Johns Hopkins Medicine using MRI scans and computer modeling say they have further pinpointed areas of the human brain that regulate efforts to deal with fatigue. The findings, they say, could advance the development of behavioral and other strategies that increase physical performance in healthy people, and also illuminate the neural mechanisms that contribute to fatigue in people with depression, multiple sclerosis . We know the physiologic processes involved in fatigue, such as lactic acid build-up in muscles, but we know far less about how feelings of fatigue are processed in the brain and how our brain decides how much and what kind of effort to make to overcome fatigue," says Vikram Chib, Ph.D., assistant professor of biomedical engineering at the Johns Hopkins University School of Medicine and research scientist at the Kennedy Krieger Institute. Knowing the brain regions that control choices about fatigue-moderating efforts can help scientists find therapies that precisely alter those choices, says Chib. "It might not be ideal for your brain to simply power through fatigue," says Chib. "It might be more beneficial for the brain to be more efficient about the signals it's sending. For the study, Chib first developed a novel way to objectively quantify how people "feel" fatigue, a difficult task because rating systems can vary from person to person. Physicians often ask their patients to rate their fatigue on a scale of 1 to 7, but like pain scales, such ratings are subjective and varied. These findings, says Chib, may advance the search for therapies -physical or chemical that target this pathway in healthy people to advance performance and in people with conditions that are associated with fatigue.