[BIC-announce] FW: Seminar in Cognitive Neuroscience - Differences between orthonasal and retronasal olfaction

[Jennifer Chew, Ms.]

PLEASE DISCARD IF THIS IS A DUPLICATE.  THANK YOU.  JENNIFER 

Jennifer Chew
McConnell Brain Imaging Centre
MNI - WB317
3801 University Street
Montreal, Qc  H3A 2B4
Telephone:  514-398-8554
Fax:  514-398-2975

________________________________________

Thomas Hummel, M.D., Ph.D.
Professor
Department of Otorhinolaryngology
University of Dresden Medical School
Dresden, Germany

Differences between orthonasal and retronasal olfaction

Thursday, May 4th, 2006
W201
3801 University Street
1:30 p.m. 



Orthonasal or retronasal presentation of certain odors in everyday life, such as cheese or fish, evokes different responses. To study this phenomenon, stimulation techniques were developed that allow
ortho- or retronasal presentation of chemosensory stimuli. Based on this technique several studies were performed investigating (1) the subjects' ratings of stimulus intensity, hedonic characteristics of the stimuli, and stimulus quality, (2) the peripherally obtained electro-olfactogram, (3) the EEG-derived olfactory event-related potentials, and (4) cerebral activation using functional magnetic resonance imaging. Additional experiments investigated (5) the differential sensitivity of the nasal mucosa to trigeminal stimuli. 
Finally, (6) 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, and (ii) subtle differences in nasal airflow, and 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.


http://www.tu-dresden.de/medkhno/hummel.htm


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