The Impact of Reward-induced Dopamine Release on Functional Connectivity: a Combined PET/fMRI Study

Aim 1. To test the relationship between reward-induced dopamine (DA) release on changes in
resting state functional connectivity (RSFC) in healthy subjects. In 20 healthy adults, the
investigators will examine DA release (measured using positron emission tomography, PET) in
the ventral striatum, thalamus, and prefrontal cortex, as previously described. Before and
after the task the investigators will examine RSFC (measured using functional magnetic
resonance imaging, fMRI) between these structures, which have been shown to form functional
pathways serving motivation and emotion regulation in rodents and nonhuman primates. The
investigators hypothesize that DA release will impact the functional relationship between
these and other structures as determined by changes in RSFC.

Aim 2. To examine the relationship between dopamine release and the Reward Positivity (RewP)
potential. Subjects will be presented with the option to participate in an event-related
potential (ERP) study. The investigators will correlate the amount of DA release with the
amplitude of the RewP potential, an ERP that is enhanced in reward versus non-reward
circumstances. Based on previous studies, the investigators hypothesize that RewP amplitude
will positively correlate with dopamine release in the nucleus accumbens.

Inclusion Criteria:

1. Healthy men and women age 18-45 who have the capacity to consent to the protocol.

2. Ability to understand and follow instructions and oriented to name, time, and place.

3. A negative urine pregnancy and toxicology screen

4. Willingness to abstain from using aspirin, NSAIDs, or anticoagulants during the study

Exclusion Criteria:

1. Left-handed or ambidextrous

2. History of seizures

3. History of strokes

4. Clinically significant, uncontrolled liver, kidney, cardiac, or pulmonary disease

5. Terminal medical diagnosis consistent with survival < 1 year

6. Serious mental impairment. Mini mental state exam of < 23/30

7. Current or past DSM-IV Axis I or neurologic disorders

8. Actively abusing substances, including alcohol (regular alcohol use during the past 6
months equal to or greater than 16 cans of beer per week or equivalent; use of street
drugs or regular tobacco use during the past 6 months)

9. Unstable medical condition (≥ 3 months), or serious medical illnesses during the past
three months (e.g., serious infections)

10. Unexplained loss of consciousness; history of traumatic brain injury involving loss of
consciousness greater than 2 minutes

11. Currently pregnant or breastfeeding, sexually active and of child-bearing potential
and not using adequate contraceptive methods

12. Childbirth or miscarriage during past 6 months, breastfeeding within 6 months of
recruitment

13. Allergic to latex and/or study pharmaceuticals

14. Diabetes and/or unable to fast for up to 7 hours

15. Unable to lie comfortably in the scanner for up to 4 consecutive hours

16. Would receive a total of over 5 rems to a radiosensitive organ (bone marrow, gonads,
lens of the eye) or 15 rems to any other organ or to the body as a whole during a 12
month period

17. Contraindications for MRI including neurostimulators, implanted medical devices, metal
in the body, claustrophobia, weight over 440 pounds, and girth size incompatible for
scanner bore.

18. Participation in a similar Social Feedback Task within 2 months of the start of the
study.