Measure Striatal Adenosine-dopamine Receptors Interactions: from Molecule to Behaviors
Hsiao-Ying Wey
Summary
This research study aims to determine whether and how caffeine intake affects learning process through reward feedback compared to placebo. The data acquired from this study would improve our understanding on the consequence and mechanism of caffeine intake in the aspect of learning process. Participants will perform a reinforcement learning task (i.e. Probabilistic Selection Task) and a motor inhibition task (i.e. Go/NoGo task) in a brain scan. The scan will be done with the Siemens Biograph mMR positron emission tomography (PET)/ magnetic resonance imaging (MRI) 3 Tesla scanner. The PET allows us to see the changes in the "reward signals" - dopamine - in the brain using a radioactive dye called \[11C\]Raclopride. The MRI, on the other hand, enables us to take detailed pictures of the brain activities during cognitive tasks using a high-powered magnet. Reviewing these pictures will help us understand the influence of caffeine on reward signals and brain activities during the learning process.
Description
Adenosine 2A receptors (A2AR) colocalize with and exerts allosteric antagonism to dopamine D2 receptors (D2R) by co-forming functional heterodimers in the striatum. Preliminary studies using positron emission tomography (PET) with \[11C\]Raclopride have shown increased D2/D3R availability by A2AR antagonism with caffeine and decreased D2/D3R availability by enhanced adenosine signaling during sleep deprivation, supporting the notion of A2AR-D2R interactions in vivo. However, how A2AR-D2R interactions contribute to D2R-mediated neurocognitive functions is scarcely investigated. Reinforcement l…
Eligibility
- Age range
- 18–45 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion Criteria: * Age ≥ 18 and ≤ 45. * Habitual caffeine intake ≥ 100 mg and ≤ 450 mg daily. * Non-smokers. * Clinically healthy. * Have normal vision or corrected to normal vision. Exclusion Criteria: * Pregnant or lactating women. * Women using hormonal contraceptives. * BMI \< 18.5 or \> 29.9 * Sleep disturbance or extreme chronotype. * Urine test positive on one of the following substances: benzoylecgonine, morphine, d-Methamphetamine, d-Amphetamine, Benzodiazepines, Secobarbital, Methadone, Buprenorphine Glucuronide, Nortriptyline, MDMA, Oxycodone, PCP, Propoxyphene, and Cannabis/T…
Interventions
- DrugCaffeine (200 mg)
Caffeine (200mg) will be administered per os 20 minutes prior to the PET/fMRI data acquisition.
- DrugPlacebo
Lactose tablet will be administered per os 20 minutes prior to the PET/fMRI data acquisition.
Location
- Athinoula A. Martinos Center for Biomedical ImagingCharlestown, Massachusetts