BACKGROUND&AIMS: Changes in gut microbiota have been reported to alter signaling mechanisms, emotional behavior, and visceral nociceptive reflexes in rodents. However, alteration of the intestinal microbiota with antibiotics or probiotics has not been shown to produce these changes in humans. We investigated whether consumption of a fermented milk product with probiotic (FMPP) for 4 weeks by healthy women altered brain intrinsic connectivity or responses to emotional attention tasks. METHODS: Healthy women with no gastrointestinal or psychiatric symptoms were randomly assigned to groups given FMPP (n=12), a non-fermented milk product (n=11, controls), or no intervention (n=13) twice daily for 4 weeks. The FMPP contained Bifidobacterium animalis subsp. Lactis, Streptococcus thermophiles, Lactobacillus bulgaricus, and Lactococcus lactis subsp. Lactis. Participants underwent functional magnetic resonance imaging (fMRI) before and after the intervention, to measure brain response to an emotional faces attention task and resting brain activity. Multivariate and region of interest analyses were performed. RESULTS: FMPP intake was associated with reduced task-related response of a distributed functional network (49% crossblock covariance; P =.004) containing affective, viscerosensory, and somatosensory cortices. Alterations in intrinsic activity of resting brain indicated that ingestion of FMPP was associated with changes in midbrain connectivity, which could explain the observed differences in activity during the task. CONCLUSIONS: Four weeks intake of a FMPP by healthy women affected activity of brain regions that control central processing of emotion and sensation.