MRS Measurement of Glutamate and GABA Metabolism in Brain

* INCLUSION CRITERIA:
* 18-65 years of age
* Able to give written informed consent
* Healthy based on medical history and physical exam
* Enrolled in Protocol 01-M-0254 or Protocol 17-M-0181

EXCLUSION CRITERIA:

* Any current Axis 1 diagnosis
* Clinically significant laboratory abnormalities
* Positive HIV test
* Metallic foreign bodies that would be affected by the magnetic resonance imaging (MRI) magnet, or fear of enclosed spaces likely to make the subject unable to undergo an MRI scan.
* History of neurological illness or injury with the potential to affect study data interpretation, such as multiple sclerosis, Parkinson s disease, seizure disorder or traumatic brain injury
* Prescription psychotropic medication, drug free less than 8 weeks (anticholinergics, benzodiazepine, fluoxetine, antipsychotics, and anticonvulsants)
* Serious medical illness as determined from H\&P or laboratory testing including Diabetes
* Inability to lie flat on camera bed for about two and a half hours
* Pregnant or breastfeeding
* Current substance use disorder based on DSM-5
* NIMH employees and staff and their immediate family members will be excluded from the study per NIMH policy.