Inclusion Criteria:  Healthy adult, age = 18 years;  Visual, hearing , oral or written capacities and expression sufficient for the suitable realization of the tests; Obtaining of the informed consent of the subject.  Exclusion Criteria:  Subjects presenting a neurological, psychiatric history; Subjects under chronic medication which can influence the intellectual activity; Subjects presenting a contraindication to the MRI (carriers of a pacemaker, an implanted material(equipment) activated by an electric, magnetic or mechanical system, carriers of haemostatic clips of anévrysmes intracérébraux or carotid arteries, carriers of orthopaedic, claustrophobic implants); Subjects refusing to be informed about the possible presence of an anatomical anormality; administrative Problems: impossibility to give about the information, no insurance, refusal to sign the consent, under guardianship subject ; Subjects participating in another protocol • pregnancy