Single Arm for Chronic Fatigue Syndrome

Background: The way the brain processes rewards and punishments may play a role in some disorders of the nervous system. People with chronic overlapping pain conditions (such as myalgic encephalomyelitis/chronic fatigue syndrome \[ME/CFS\]) may have heightened responses to unpleasant, punishing sensations. Some of these conditions may also cause heightened responses to effort; this is an unpleasant sensation felt during physical and mental exertion. Objective: To learn more about how the brain processes different unpleasant sensations. Eligibility: People aged 18 to 50 years with ME/CFS. Healthy volunteers are also needed. Design: Participants will have 3 visits in 1 to 5 weeks. Visit 1: Participants may have a neurologic exam. They will have a mock magnetic resonance imaging (MRI) scan. They will lie on a bed in a wooden tube while they practice 2 tasks: Thermal pain rating: A device that creates mild to moderate heat will be placed on one leg. Physical effort rating: Participants will squeeze a plastic bar with different levels of force. Visit 2: Participants will have a real MRI scan. They will lie on a table that slides into a large tube. Visit 3: Participants will have another MRI scan. They will repeat the thermal pain and physical effort tasks while in the scanner. Sensors will be placed on 1 arm to measure how the muscles function as they squeeze the bar. Their heart rate will be tested: They will hold their finger against a camera lens for 1 minute. They will do 2 other tasks: 1 requires repeatedly pressing a key on a keyboard, and the other requires squeezing a bar.