Social cognition is a complex process that enables humans to interpret social information and behave appropriately in a social environment. Social cognition can be impaired in Parkinson's disease patients, worsening quality of life and relationships with those around them, even at an early stage. These alterations are manifested in particular by impairments of the recognition of facial emotions and body movements, involving the motor system. The aim of this study is to understand the brain mechanisms associated with impaired social perception in people with Parkinson's disease using functional MRI and a behavioural task for the perception of social interaction scenes depicted by "Point Light Display" (PLD).This study will investigate the effect of dopaminergic modulation on the networks associated with the perception of movement and mirror system, the observation of action (parietal cortex, superior temporal sulcus), and those associated with the mentalization of others' cognitive or emotional states (prefrontal cortex and limbic system).

The study is thus divided into 2 stages.

• Stage 1 "preliminary": Preliminary validation of the experimental task
• Stage 2 "imagery": Assessment of brain activity (BOLD signal) related to social perception in imaging

Inclusion Criteria:

• Male or female between 30 and 75 years of age
• Freely-given informed consent to participate to this study (written form)
• Affiliated with a social security system or equivalent;
• Person diagnosed with Parkinson's disease according to MDS-UPDRS criteria for at least 3 years and receiving dopaminergic treatment (e.g. : LEVODOPA, CARBIDOPA, BENZERASIDE, ENTACAPONE, MODOPAR, SINEMET, STALEVO, PRAMIPEXOLE, SIFROL, ROPINIROLE, REQUIP ; ROTIGOTINE, NEUPRO, PIRIBEDIL, TRIVASTAL, RASAGILINE, AZILECT, CONTAM, AMANTADINE, MANTADIX, APOMORPHINE, APOKINON, DOPACEPTIN, FOSLEVODOPA, FOSCARBIDOPA, SCYOVA) (for patients only)
• Effective contraception for women of childbearing age or post-menopausal women (only for patients and healthy volunteers in stage 2 "imaging")
• Requiring dopa testing as part of routine care (only for patients in stage 2 "imaging")
• No disabling cognitive impairment (MOCA score ≥ 26)
• No diagnosis of chronic disease associated with disability (only for healthy volunteers)

Exclusion Criteria:

• Contraindication to MRI (only for patients and healthy volunteers in step 2 "imaging"):

  • Wearing a pacemaker not approved for 3 Tesla MRI
  • Presence of intracerebral ferromagnetic or magnetizable material
  • Presence of intraocular ferromagnetic or magnetizable foreign bodies
  • Presence of non-removable ferro-magnetic or magnetizable foreign bodies in the cephalic region
  • Claustrophobia

• History of head trauma with loss of consciousness lasting more than 30 min (only for patients and healthy volunteers in step 2 "imaging")

• Participant not agreeing to be informed in the event of incidental discovery of an abnormality on MRI (only for patients and healthy volunteers in stage 2 "imaging")

• Tremor or disabling dyskinesias preventing MRI (only for patients in stage 2)

• Having exceeded the annual amount of compensation allowed for participation in research protocols (only for healthy volunteers)

• Pregnant, parturient or breast-feeding women

• Persons deprived of liberty by judicial or administrative decision

• Persons under psychiatric care

• Persons admitted to a health or social institution for purposes other than research

• Adults under legal protection (guardianship, curatorship)

• Participants in other intervention research involving a period of exclusion still in progress at the time of pre-inclusion.