Aims :

• exploring lorazepam (0.038 mg/kg) effects, after a single oral intake, in healthy volunteers, on the neural correlates of encoding and retrieval of information during a word-stem completion task (implicit memory), using fMRI
• comparing lorazepam effects to diazepam (0.3 mg/kg)effects
• exploring benzodiazepines effects, after a single oral intake, on the neural correlates of successful encoding of information within explicit memory using fMRI

Hypothesis :

• both diazepam and lorazepam will impair explicit memory performance, but lorazepam only will impair perceptual priming
• lorazepam and diazepam will modify the normal correlates of information encoding within explicit memory
• lorazepam only will alter the neural correlates of perceptual priming

Inclusion Criteria:

• Healthy subjects between 18 and 30 years
• Students in medicine, dentistry or pharmacy
• French as a mother language

Exclusion criteria:

• Medical condition influencing brain function (neurological or psychiatric)
• Asthma
• General anesthesia in the 3 last months
• Drug addiction (DSM IV criteria)
• Regular medical treatment (except contraceptive pill)
• Significant impairment observed during a medical examination including ECG
• Intake of any psychotropic drug that can have a effect during testing
• IQ (Wechsler) < 100
• FMRI contra-indication (implantable magnetic material, claustrophobia)
• Known allergy to benzodiazepine or lactose
• > 10 cigarettes/day
• Pregnant or breast-feeding woman
• No health insurance
• Subjects who do not complete the entire study