Opioidergic and Noradrenergic Systems in Central Parkisonian Pain

Inclusion Criteria: * Diagnosis of Parkinson's disease based on MDS-UPDRS criteria (Group 1 and 2) * Dopaminergic therapy stable with stable dose for at least 4 weeks prior to J0 * Affiliate to a social security or similar system * Having given written consent to participate in the study, free and informed. * Having chronic pain more than 3 month (Group 1) * Without chronic pain (Groupe 2 and 3) * Having central pain using specific algorithm (Marques et al., 2019) * Having pain intensity at least 4 on VAS (Visual Analogue Scale) during the last month (Group 1) * Having pain intensity lower than 3 on VAS (Visual Analogue Scale) during the last month (Group 2 and 3) Exclusion Criteria: * Having atypical Parkinson's disease (Group 1 and 2) * Parkinson's disease with disabling dyskinesia and/or severe tremor (Group 1 and 2) * Any contraindications to having a brain MRI or PET scan (e.g., pacemaker, metal foreign body, claustrophobia, deep brain stimulation or apomorphin pump unable to be turn off) * History of head trauma with loss of consciousness lasting more than 30 minutes * Not agreeing to be informed in the event of incidental discovery of an abnormality on MRI or during neuropsychological assessment * Presence of cognitive dysfunction (defined as MoCA score \< 24) * Severe depression (BDI \> 29) * unable to stop the opioid treatment the week before the imaging exam ( e.g., Antarène codéine, Claradol codéine, Codoliprane, Dafalgan codéine, Euphon, Klipal, Lindilane, Néo-codion, Paderyl, Prontalgine, Pulmoserum, Tussipax ; Opium : Izalgi, Lamaline, Colchimax, Dropizal ; Morphine : Actiskenan, Moscontin, Oramorph, Sevredol, Skenan ; Buprénorphine : Bupensan, Buvidal, Orobupre, Sixmo, Suboxone, Subutex, Temgesic, Zubsolv ; Dihydrocodéine : Dicodin ; Hydromorphone : Sophidone ; Nalbuphine : Nalpain ; Fentanyl : Abstral, Actiq, Breakyl, Durogesic, Effentora, Instanyl, Matrifen, Pecfent, Recivit ; Méthadone : Methadone AP-HP, Zorvon ; Oxycodone : Oxsynia, Oxycontin, Oxynorm, Oxynormoro ; Tramadol : Biodalgic, Contramal, Ixprim, Monoalgic, Monocrixo, Orozamudol, Skudexum, Topalgic, Zaldiar, Zamudol, Zumalgic) * unable to stop any treatment * Treated with level 1 analgesics (NSAIDs, acetaminophen) or coanalgesics (antidepressants, antiepileptics) unless treatment has been stable for at least 4 weeks prior to the study and does not interfere with the noradrenergic system (list above). * Presenting or having presented a dependence on any addictive substance according to DSM-IV-TR criteria, with the exception of tobacco. * Having used recreational drugs interfering with the opioid and noradrenergic systems (cannabis, CBD, opiates, MDMA, ecstasy) in the last 3 months or chronic use * Pregnant women, women in labor or nursing mothers * Persons deprived of their liberty by judicial or administrative decision * Under psychiatric care * Admitted to a health or social institution for purposes other than research * Under legal protection (guardianship, curatorship) * Participant in another interventional study with an exclusion period still in progress at pre-inclusion * Having exceeded the annual amount of compensation authorized for participation in research protocols