The purpose of this study is to evaluate the effect of a commercially available fermented dairy product containing probiotics (4 weeks, twice a day) on the brain activity within specific neural circuits regulating the subjective experience of emotional valence and digestive well-being.

Inclusion Criteria:

• Healthy women, right-handed, aged from 18 to 60 years
• Subject of normal body weight or with overweight i.e. not obese (body mass index between 18 and 30 kg/m2).
• For fertile women, complying with one of the other medically approved methods of contraception

Exclusion Criteria:

• Subject with any current psychiatric or eating or suicidal attempt disorder, or history of such disorder.
• Subject with any history of chronic GI disorder or disease.
• Subject with any significant active or prior metabolic disorder or disease.
• Subject with any use of probiotic supplements or antibiotics in the previous month.
• Subject with current use of any medications with potential central nervous system effects (antidepressants, anxiolytics, opiate pain medications...).
• Subject with allergy or hypersensitivity to milk proteins or lactose intolerance or immunodeficiency
• Subjects with claustrophobia or other condition (such as metallic implants) that would preclude MRI scanning