• Global Cognitive Assessment [ Time Frame: Day 2 - 10 minutes ]
  Measured with Montreal Cognitive Assessment. Outcome measure is between 0 and 30. A score of 26 or over is considered to be normal.
• Memory Assessment [ Time Frame: Day 2 - 20 minutes ]
  Measured with the 16-item Free and Cued Recall test. Outcome measure is the total immediate recall which is the sum of free and cued recall.
• Working Memory Assessment [ Time Frame: Day 2 - 20 minutes ]
  Measured with the Digit Span Memory test. Outcome measure is the total number of items correctly repeated.
• Executive Functioning [ Time Frame: Day 2 - 20 minutes ]
  Measured with the Trail Making test. Unit of measure is first seconds to perform the test, which will be converted in a percentile score and then number of errors made during the test.
• Planning Functioning [ Time Frame: Day 2 - 20 minutes ]
  Measured with the Tower of London test. Outcome measure is the total correct and total moves score.
• Visuo-spatial Assessment [ Time Frame: Day 2 - 20 minutes ]
  Measured by the Visual Object and Space Perception Battery. The study will use a selection of theses tests : incomplete letters (outcome measure is between 0 and 20; cut-off score = 16) and position discrimination (outcome measure is between 0 and 10; cut-off score = 7)
• Depression Evaluation [ Time Frame: Day 2 - 10 minutes ]
  Measured by the Beck Depression Inventory-II Questionnaire. Outcome measure is between 0 and 20 with a cut-off score = 13. A score higher than 14 indicates the presence of depression.
• Anxiety Evaluation [ Time Frame: Day 2 - 10 minutes ]
  Measured by the State-Trait Anxiety Inventory (STAI) form Y questionnaire. Outcome measure is between 20 and 80, with higher scores correlating with greater anxiety.
• Praxic Abilities [ Time Frame: Day 2 - 10 minutes ]
  Measured by the Mahieux Praxic test. Outcome measure is between 0 and 23.
• Day time sleepiness evaluation [ Time Frame: Day 2 - 5 minutes ]
  Measured by the Epworth Sleepiness Scale Questionnaire. Outcome measure is between 0 and 24 with a score between 0-8 indicating normal Daytime sleepiness, a score between 9-14 indicating mild sleep deficiency and a score above 15 an excessive daytime sleepiness.
• Sleep Quality [ Time Frame: Day 2 - 5 minutes ]
  Measured by the Pittsburgh Sleep Quality Index (PSQI). Outcome measure is between 0 and 21 with 0 indicating no sleep problem and 21 major sleep disorder.
• Olfactory assessment : odor detection [ Time Frame: Day 2 - 30 minutes ]
  The odor detection capability will be evaluated using a phenyl-ethyl alcohol (PEA) test. In this experiment, the detection threshold is obtained using a "staircase" procedure. Outcome measure is between 0 and 16 with higher score indicating better performance.
• Olfactory assessment: odor discrimination [ Time Frame: Day 2 - 30 minutes ]
  Odor discrimination capacity will be assessed by asking the participant to smell three bottles (two bottles contain the same odor, and the third contains a different smell). The test includes 16 triplets of odorous substances. Outcome measure is between 0 and 16 with higher score indicating better performance.
• Olfactory assessment : odor identification [ Time Frame: Day 2 - 30 minutes ]
  The odor identification capacity will be estimated by the European test of olfactory capacities (ETOC), a test based on 16 identifications. Outcome measure is between 0 and 16 with higher score indicating better performance.

• Other: The role of the noradrenergic system across the life span (Healthy Subjects)
  A sample (n=90) of balanced distribution of healthy males and females within a continuous segment of the adult life span from 20 to 80 years old will be recruited, with approximately 7 males and 7 females subjects for each decade of age. Each participant will undergo 1) a neuropsychological examination, 2) an olfactory screening and 3) a 90 min 11C-Yohimbine positron emission tomography (PET)/magnetic resonance imaging (MRI) scan in a resting state.
• Other: The role of the noradrenergic system across the life span (Parkinson's Disease Subjects)
  Three groups of Parkinson Disease (PD) patients (each of them n=15) will be studied according to the duration and stage of the disease: early stage (the same group in Task 2); mid stage (5-7 years of disease duration; Hoehn and Yahr in Off 2-3); late stage (7-10 years of disease duration; Hoehn and Yahr in Off 3-4).

• Experimental: Healthy controls
  Intervention: Other: The role of the noradrenergic system across the life span (Healthy Subjects)
• Experimental: Parkinson disease
  Intervention: Other: The role of the noradrenergic system across the life span (Parkinson's Disease Subjects)

Inclusion Criteria for the healthy controls:

• Age between 20 years and 80 years
• Weight between 40 kilograms (kg) and 95kg
• Without neurologic or psychiatric history
• Without head trauma history including loss of consciousness superior to 30 minutes.
• Affiliated to a social security or similar scheme
• Not subject to any legal protection measures
• Participant must have signed an informed consent document indicating that they understand the purpose of, and procedures required for, the study and are willing to participate in the study and comply with the study procedures and restrictions

Inclusion Criteria for the patients with Parkinson's disease:

• Age between 40 and 80 years old
• Weight between 40 kilograms (kg) and 95kg
• With an idiopathic Parkinson's disease (Dopa-sensitive)
• Without head trauma history including loss of consciousness superior to 30 minutes.
• Affiliated to a social security or similar scheme
• Not subject to any legal protection measures
• Participant must have signed an informed consent document indicating that they understand the purpose of, and procedures required for, the study and are willing to participate in the study and comply with the study procedures and restrictions

Exclusion Criteria:

• Subject with alcohol or substance abuse history
• Subject with somatic drug therapies
• Magnetic Resonance Imaging (MRI) contraindications (implanted or embedded metal objects in the head or body)
• Positron Emission Tomography (PET) contraindications
• Exposed to 1 millisievert or more of ionizing radiation in the year before the start of this study
• Subject unable to sign written consent for participation in the study