Recording and Modulation of Neuronal Mechanisms During Operant Conditioning: a MEG Study

Background: \- Most of the time, humans make decisions according to their consequences, especially if they will be beneficial, and will avoid or try to avoid doing an action if it has a bad outcome. The way that the brain prepares a movement has been studied in detail, but the way the brain makes decisions before carrying out an action is still poorly understood. Researchers are interested in learning more about the decision-making process and how it affects the brain. Objectives: \- To record the activity of the brain during decision-making processes. Eligibility: \- Healthy, right-handed volunteers between 18 and 40 years of age. Design: * Potential participants will have a screening visit with a medical history and neurological examination to determine eligibility. * This study requires seven visits: one magnetic resonance imaging (MRI) visit and 6 magnetoencephalography (MEG) recording visits. The MEG recording visits will include transcranial magnetic stimulation (TMS). All visits will be spaced at least 1 week apart. Total participation will last about 6 weeks. * Participants will have an MRI scan at the first study visit. * The MEG procedures will record brain activity during a series of computer tests involving winning or losing money. TMS will be performed during these visits, separate from the test....