Paracetamol is one of the most widely used analgesic in the world, indicated for the symptomatic treatment of fever and pain. The objective of this study is to evaluate the mechanism of action of paracetamol (versus placebo) in the brain with new assessment tools (functional MRI and test inducing pain by thermal stimulation.

Visit 1 / Visit 2 Inclusion of the subject, Clinical examination Trainings tests

Study period 1 Clinical examination Measurement of the basal pain thresholds Administration of product (T0) T0+100min : Thermal stimulation according to the established paradigm and fMRI data acquisition T0+180min : Thermal stimulation according to the established paradigm and fMRI data acquisition

Study period 2: same of period 1.

Inclusion Criteria:

• - Healthy volunteers
• Aged at last 18 years and over 60 years
• Male
• Non-smoking subject
• Fasting coffe, tea, coca-cola or other stimulant products since the last evening
• Subject free of any treatment within 7 days prior to inclusion including no use of analgesics or anti-inflammatory treatments

Exclusion Criteria:

• Contraindications to the administration of paracetamol
• Contraindications to the completion of MRI
• Medical history and/or surgical judged by the investigator as being incompatible with the test
• Progressive disease at the inclusion