In addition to the imaging procedures detailed above, we also plan to acquire imaging data on healthy individuals with similar timeline. Healthy volunteers will be scanned three times; the first and second scans will be 24-48 hours apart, while the second and third scans will be two weeks apart. The imaging sessions will follow the same protocol as in the patients. The collection of control data is necessary in order to demonstrate that imaging findings are not due to acclimatization to scanner environment or other confounding sources. Compensation for participating in the MRI component is $75 per MRI.