Study of Volition: Behavioral Analysis and Clinical Neurophysiological Analysis

Background: 'Free will' can be defined as the belief that people have control over their thoughts and movements. The topic of free will is controversial and is still being debated. Science has only partial answers to questions about free will, so researchers want to learn more about it. They want to assess the role of consciousness when intentions are present with behavior. This could help to explain the causal role of consciousness in movement or decisions. Objective: To learn more about free will. Eligibility: Healthy, right-handed adults ages 25-45 Design: Participants will be screened with medical history, physical exam, and neurological exam. Participants will have 1 study visit. It will last up to 4 hours. Participants will sit in a comfortable chair in front of a screen. They will perform some or all of the following tasks. Visual Task. Participants will watch different stimuli on the screen and answer simple questions. Electroencephalography (EEG). An EEG records the electrical activity of the brain ('brain waves'). For the EEG, small electrodes are put on the scalp with an electrode cap. A gel is placed in the space between the electrodes and the scalp. Participants' brain waves will be recorded, including while they decide whether to move their thumb. Choice/Reaction Time Task. Participants will watch different stimuli on the screen and react to them by moving their wrist. During this task, they will wear an EEG cap on their head and electrodes on their arms and wrists. Electromyography. Small electrodes will be attached to participants' skin. Their muscle activity will be recorded while they decide whether to move their wrist and during the movement itself. Transcranial Magnetic Stimulation (TMS): TMS is a non-invasive brain stimulation that uses magnetic field to stimulate nerve cells in your brain. TMS can increase or decrease brain activity in particular area of your brain. TMS operates completely outside of the body and is generally very