Background:
People with substance use disorder (SUD) often have changes in brain function that can make it difficult to control drug-seeking behavior. These changes may heighten the urge to use drugs or lessen the desire to seek nondrug-related rewards. Researchers want to know how a technique called transcranial magnetic stimulation (TMS) may cause changes in brain activity that may help people with SUD.
Objective:
To test TMS in healthy volunteers.
Eligibility:
Healthy people aged 18 to 45 years who are right-handed.
Design:
Participants can volunteer for up to 5 different experiments. Each experiment requires 2 to 8 clinic visits. Each visit will last 3 to 7 hours.
Some visits will include TMS. A coil will be placed on the participant s head. A brief electrical current will pass through the coil to create a magnetic field. Participants may feel a tapping or pulling sensation on the skin under the coil. They may feel a twitch in their face, neck, arm, or leg muscles. Participants may be asked to tense certain muscles during TMS.
Some visits will include functional magnetic resonance imaging (fMRI) scans. Participants will lie on a bed that slides into a large tube. They will perform tasks on a computer inside the tube. The fMRI will show which parts of the brain are used during each task.
Participants will perform tasks on a computer. Some tasks may be done at a desk as well as during TMS and fMRI. Participants may look at images, listen to sounds, smell odors, or taste flavored liquids. Their vital signs may be monitored and their eye movements may be tracked during tasks.
Aged 18-45 years old. Justification: Many neural processes change with age, and these changes could introduce unwanted variability in the measured signals.
In good general health based on the assessment of the MAI.
Right-handed.
Any neurological disorder that would increase seizure risk from TMS such as stroke, brain lesions, previous neurosurgery, epilepsy, any history of seizure or fainting episode of unknown cause, frequent severe headache, or head trauma resulting in loss of consciousness, lasting over 30 minutes or with sequela lasting longer than one month. The MAI will also retain discretion to exclude based on a history of a neurological illness or trauma that may compromise safety or data integrity.
Predisposition to seizures (e.g., first-degree family history of potentially hereditary epilepsy, etc.).
Current use (any use in the past two weeks, daily use for more than one week within past 3 months) of any investigational drug or of any medications with psychotropic (e.g., benzodiazepines, etc.), anti or pro-convulsive action. This will be determined at the discretion of the MAI.
Unable to undergo MRI or TMS due to certain metallic or magnetic devices or implants in the body, claustrophobia, or other reasons.