The aim of this research project is to better understand the reciprocal influence of visual and olfactory systems on cerebral activity evoked by odors and visual stimuli. Given the importance of olfacto-visual learning in expert situations, the degree of expertise in olfaction will also be considered. In addition, the investigators will try to better understand the differences between expert and non-expert populations in olfaction through different levels of approach: sensory, genetic and cerebral. To achieve this, the investigators will use psychophysical tests, genetic analyzes and a non-invasive technique, functional magnetic resonance imaging (fMRI) to measure the brain activity of human subjects - novices or experts in olfaction - in response to different visual and olfactory stimuli.

Inclusion Criteria:

• healthy volunteers
• men and women, aged 18-85 years old
• subjects with social security cover
• expertise in olfaction for half of the subjects (60)

Exclusion Criteria:

• subjects younger than 18 and older than 85
• subjects with contraindications to fMRI, i.e. with pacemaker / insulin pump / metal prosthesis / intracerebral clip / neurosensory stimulator / implantable defibrillator / cochlear implants / ferromagnetic ocular or cerebral foreign body close to the nerve structures / ventriculoperitoneal neurosurgical bypass valves / braces and other non-removable metallic dental device / claustrophobic, non-cooperating or agitated subjects.
• pregnant or breastfeeding women
• subjects with known olfactory disorder
• subjects with known neurological disorder