ABSTRACT
The differences between orthonasal and retronasal olfaction in these important aspects of behavior are still being elucidated. To understand the function of retronasal olfaction, we must first understand the anatomy of olfaction. Orthonasal olfaction preferentially enhanced discharge of the insula and amygdala whenever retronasal olfaction induced greater activation of the anterior cingulate cortex. The threshold for orthonasal and retronasal olfaction is also different. Retronasal olfaction occurs during exhalation, when air is pushed up to the nose from the pharynx. Since the stimulus is delivered from the mouth to the nose, this is retronasal olfaction. Despite the presence of multiple sensory systems, isolated retronasal olfaction has been studied. Moreover, retronasal olfaction plays a critical role in food hedonics. Retronasal olfaction has been demonstrated to evoke different sensations when odors were presented orthonasally. However, there has been limited research examining how retronasal olfaction specifically affects human behaviors.
