After few years of evolution, patients with Parkinson's disease may develop apathy, with different degrees of severity. Apathy is characterized by a loss of interest for the others and for activities. The lack of social interactions in these patients may be due to an impairment in decoding emotional facial expression. Indeed, facial expression recognition, which is necessary to understand other's emotional state, requires a subclinical facial mimicking of the expression observed. Yet, one of the clinical signs of PD is amimia.

This study aims to determinate if there is a facial mimicry disorder in PD ( Parkinson's disease )patients with emotional facial expression (EFE) recognition impairment, compared to healthy control subjects. We also want to know if this facial mimicry disorder is primary (subtended by facial mobility impairment, that is to say amimia) or secondary (related to the mirror neuron systems that allows us to activate similar neural networks when observing and feeling a specific emotion)

20 patients with an Idiopathic Parkinson's disease

+ 20 paired healthy volunteers (on sex, age, and education)

After inclusion, patients are evaluated two times: they are studied without medication (MED OFF) and with medication (STIM ON) in a randomized order. The 2 evaluations should be spaced out 15 days to one month (J0 and J+15d)

Healthy subjects have only one visit J0 (inclusion and emotional facial expression recognition tests are made at the same time)

Inclusion Criteria:

• Patients with idiopathic Parkinson's disease according to UKPDSBB criteria - Men or women aged between 18 to 75 years

• Free from any visio-perceptive disorder (visual acuity and Vitec)

• Affiliated to National Health system

• Having given their informed consent

  --Healthy controls

• Men or women aged between 18 to 75 years

• Free from any visio-perceptive disorder (visual acuity and Vitec)

• Affiliated to National Health system

• Having given their informed consent

Exclusion Criteria:

• With dementia or with significant dysexecutive disorder (MMS <24, MATTIS< 130)

• With fluctuations (<5 Levodopa intakes / day)

• With severe depression (BDI > 27)

• With psychiatric comorbidities (hallucinations, psychos) evaluated with l'Unified Parkinson's disease Rating Scale part I (UPDRS part I =0)

• With faces processing disorder (Benton < 39)

• Pregnant

• Treatment with deep brain stimulation

• Under guardianship

• In excluding period for another study

  --Healthy controls

• Suffering of neurological or psychiatric evolutive condition

• With severe depression (BDI > 27)

• With faces processing disorder (Benton < 39)

• Pregnant

• In excluding period for another study