In 1989, researchers agreed that the “amygdala” (there is one on each side of the inner brain) plays a major role in storing and releasing emotional trauma and that aromas have a profound effect in triggering responses from the amygdala. Dr. Joseph Ledoux of New York Medical University was one of the first to suggest that the use of aroma could be a major breakthrough in helping to trigger the release of pent up emotional trauma.
In email from Life Science Publishing, Aug 17, 2011