Effects of direct cedrol inhalation into the lower airway on brain hemodynamics in totally laryngectomized subjects

A previous study reported that when cedrol (odorant) is inhaled directly through the lower airway of the trachea, it decreases the sympathetic nervous activity and blood pressure in totally laryngectomized subjects (Umeno et al., 2008). In the present study, totally laryngectomized subjects were asked to inhale cedrol into the lower airway in the same manner and its effects on regional cerebral blood flow (rCBF) were analyzed. Our results indicated that hippocampal rCBF was bilaterally increased during cedrol inhalation as compared to the inhalation of blank air. These results provide the first evidence that an odorant in the lower airway modulates autonomic activity via the central nervous system.