Virtual Reality and Concept of Control in the Treatment of Acrophobia

Inclusion Criteria of all subjects: * 18 to 60 years old * Male or female * All subjects will be fluent in French. * Fully informed and freely given, signed Informed consent in written form. * Patient / Subject affiliated or beneficiary of a social/health security insurance. Inclusion criteria for acrophobic patients: * Patients not hospitalized suffering from acrophobia (according to DSM-IV, APA 2000). * Patients receiving pharmacotherapy (anxiolytics, hypnotics, etc.) may be included provided they are stabilized on treatment for at least 8 weeks. * Score inferior to 6 at the Behavioural Avoidance Test Inclusion criteria for healthy volunteers: * People not hospitalized showing no sign of acrophobia. * Score superior or equal to 10 at the Behavioural Avoidance Test. Exclusion Criteria for all subjects: * Pregnant woman (urine and blood β -HCG test) or lactating (contraindication to PET-scan). * Women of childbearing potential without effective contraception (contraindication to PET-scan). * Subject participating in another research evaluating other treatments including a period of exclusion still ongoing. * Persons under guardianship and adults subject submitted to a measure of legal protection or unable to consent. * Persons deprived of their liberty by a judicial or administrative decision, those hospitalized without consent under Articles L. 3212-1 and L. 3213-1 that do not fall under the provisions of Article L. 1121-8 and admitted to a health or social institution for purposes other than research. * People with a non-stabilized diabetes (contraindication to PET-scan). * Addictions to alcohol or drugs. * Persons suffering from claustrophobia. * Contraindications to fMRI. * People with hearing loss. * Strong visual impairment (\> 5 diopters) not corrected by contact lenses. Exclusion criteria for acrophobic patients: * Patients continuing psychotherapy. * Patients suffering from other neurological disorders or comorbid psychiatric diseases than acrophobia. * Patients suffering from severe organic disorders that could disable or disrupt the therapeutic process. * The concomitant drugs at inclusion should not be modified or discontinued during the study. * No psychotherapy should be initiated during the study. Exclusion criteria for healthy volunteers: \- Subjects with a known psychiatric or neurological disorders, diagnosed for depression, with emotional disorders affecting their perception of the environment, or taking a medication that may affect the auditory and visual perception, concentration or emotions.