Background: The aim of this study was to evaluate in how far cerebral blood flow changes in male subjects when exposed to a pheromone that they cannot consciously smell.
Methods: We used a boar taint steroid (5a-Androst-16-en-3-one), which is similar to human axillary sweat but could not be detected by the human volunteers who participated in this study.
Results: The pheromone produced activation of the orbitofrontal and frontal cortex in comparison to a baseline condition. The same regions were activated when the subjects smelled a rose-like odour.
Conclusion: This study shows that a pheromone, which is not consciously detected, can evoke a response in the brain that is similar to a detectable odour.