Perceptual differences between chemical stimuli presented through the ortho- or retronasal route

Abstract

Orthonasal or retronasal presentation of certain odours in everyday life, such as cheese or fish, evokes different responses. To study this phenomenon, stimulation techniques were developed to allow ortho-or retronasal presentation of chemosensory stimuli. Based on this technique, several studies were performed to investigate: (a) the subjects' ratings of stimulus intensity, hedonic characteristics of the stimuli, and stimulus quality; (b) the peripherally obtained electro-olfactogram; (c) EEG-derived olfactory event-related potentials; and (d) cerebral activation using functional magnetic resonance imaging; additional experiments investigated (e) the differential sensitivity of the nasal mucosa to trigeminal stimuli; and finally (f) clinical observations were obtained from patients with nasal polyposis with regard to ortho-or retronasal presentation of chemosensory stimuli. Summarizing these results, the studies indicate that there are perceptual differences in relation to ortho-and retronasal stimulus presentation. They appear to relate to: (i) contextual effects; (ii) subtle differences in nasal airflow, therefore access of stimuli to the olfactory epithelium may play a role in perceptual differences; in addition (iii) differential trigeminal sensitivities of the respiratory epithelium, possibly in combination with (iv) differential wiring of olfactory receptor neurons, may contribute to the observed differences in the perception of stimuli presented through the ortho-or retronasal routes.

The Way an Odor Is Experienced during Aversive Conditioning Determines the Extent of the Network Recruited during Retrieval: A Multisite Electrophysiological Study in Rats

“…Odorant molecules of the aliment could indeed reach the olfactory epithelium either via the nose (orthonasal olfaction) or via the nasopharynx when food is introduced into the mouth (retronasal olfaction) during eating and drinking (Pierce and Halpern, 1996). Psychophysical data indicate that the same odor delivered through the two routes could have different perceptual qualities (Rozin, 1982;Sun and Halpern, 2005;Hummel et al, 2006). This assumption was recently supported by dissimilarities in functional MRI brain activations (Small et al, 2005) and in event-related potentials (Hummel and Heilmann, 2008) according to orthonasal or retronasal odorant stimulations.…”

Consumer freshness perceptions of breads, biscuits and cakes

“…This difference might be expected, given participants' inability to evaluate products based on appearance, taste, flavour and texture when evaluating the product based on odour only. Previous observations have shown that certain foods appear to be sensed differently, depending on the mode of presentation (Hummel et al, 2006). In their study attention was drawn to the interaction between the chemosensory modalities (i.e.…”

Odorant Release from Alcoholic Beverages

“…Odor is sensed orthonasally, while aroma is sensed retronasally (1). It has been reported that the perception of volatile compounds by the two routes is different (2,3). This has been explained by the need for humans to use the sense of smell in two different ways.…”