Functional Neuroimaging to Detect the Neural Signatures of the Unpleasantness of Pain and Effort

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.

Study Description: This protocol will examine the associations between brain activation and the subjective unpleasantness associated with pain and physical effort in healthy individuals. We have developed two behavioral tasks for administration during neuroimaging: a Thermal Pain Rating task and a Physical Effort Rating task, which will allow us to identify brain regions in which activity is associated with the unpleasantness of these experiences. We hypothesize that the unpleasantness of the experiences will be associated with activity in a recently identified network of brain regions thought to be involved in computing subjective value, known as the subjective valuation network (SVN). Objectives: Primary Objectives: 1. Determine which regions of the SVN are specifically involved in the subjective experience of unpleasantness associated with sensations of pain. 2. Determine which regions of the SVN are specifically involved in the subjective experience of unpleasantness associated with sensations of physical effort. Endpoints: Primary Endpoints: 1. SVN regions in which activity is significantly associated with unpleasantness of pain. 2. SVN regions in which activity is significantly associated with unpleasantness of physical effort.