Major depression disorder (MDD) is a frequent and disabling mental disorder with great risk of recurrence and chronicity. Interpersonal factors are among the strongest predictors of the course and duration of an episode of depression. More specifically, social rejection is one of the most environmental risk factors of MDD. Targeted rejection predicts hastened onset of major depression. On the other hand, healthy subject show prosocial behavior after social rejection to reconnect to new source of social interaction. In addition to the potential impact of social exclusion on MDD onset, depressed patients may be more prone to be rejected as they encounter interpersonal difficulties and may less be able to reconnect to the social group after rejection.

Recent neuroimaging data show that brain processing of social exclusion activate brain regions that are central to the pathophysiology of MDD. Some of these regions are also known to be activated during physical pain and may contribute to the aversive dimension of the experienced rejection. Pro-inflammatory cytokines are involved in MDD physiopathology and can induce social withdrawal behavior. Inflammation can modulate social interactions in mammals. Moreover, after a social stress such as social rejection, blood cytokines increase. At a cognitive level, self-esteem can modulate the sensitivity to social rejection.

The major objective of the trial is to study sensitivity to social signals in MDD patient compared to healthy subject.

The investigators hypothesize in MDD patient : (1) decrease of rapid facial reactions (RFR) to dynamic emotional faces expressing joy, (2) increase of RFR to dynamic emotional faces expressing sadness, (3) decrease of prosocial reaction after experimental social rejection.

Secondary objective is to identify psychological and biological mediators We hypothetize in MDD patient: (1)mediating effect of systemic inflammatory cytokines, an (2) mediating effect of state self esteem 30 MDD patients and 60 healthy subject will be included. They will encounter psychiatric and psychometric evaluation. Their facial EMG will be recorded to assess RFR to dynamic emotional faces created by photo morphing from KDEF emotional faces database, coupled to occulometric recording. Subjects will perform cyberball game as an experimental inclusion or exclusion task and the trustgame task as an implicit evaluation of their prosocial behavior. Questionnaires will assess explicit measurement of social rejection pain and desire of affiliation. Inflammatory markers will be measured in a blood sample before the cyberball task for every subjects and 6 hours later for 20 healthy volunteers. Dosage of IL-6, IL-10, TNFa, IP-10, MCP-1, MIP-1b, Rantes, sIL-6Ra, IL1ra, VEGF, Leptin, PECAM1, sTie2, sVEGFR1, sVEGFR2 will be performed by luminex technique and usCRP, srIL2 ans sCD14 by ELISA technique.

Inclusion Criteria:

For everybody :

• benefit social health insurance
• french speaker and reader
• can stop smoking one day
• volunteer to participate

For 1st group :

• actual MDD diagnosed by a psychiatrist and meet the DSM IV criterias of MDD
• no antidepressant treatment or antidepressant treatment for less than 7 days.

Exclusion Criteria:

• BMI > 40
• weekly sport > 3 hours
• pregnancy
• fever or other infection symptoms during the last month
• significant or unstable disease, especially neurologic or inflammatory.
• recent history of coronary disease, ulcer, COPD, severe dyslipemia, kidney or liver failure.
• severe smoking addiction (fagerström > 8)
• antiinflammatory or immunomodulatory treatment during last month

For 1st group :

• no psychiatric treatment except benzodiazepin if no severe vigilance trouble and antidepressant treatment more than 7 days
• subjects under legal protection
• constraint hospitalization
• significant suicidal risk
• resistant MDD
• psychiatric comorbidity

For 2nd group :

- psychiatric disease, actual or past according to DSM IV criterias

1. st group : major depression disorder patients
2. nd group : healthy volunteers