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Knowledge on how odorants are transported through the nasal cavity to the olfactory epithelium is limited. One facet of this is how the sniffing behavior affects the abundance of odorants transferred to the olfactory cleft and in turn influences odor perception. A novel system that couples an online mass spectrometer with an odorant pulse delivery olfactometer was employed to characterize intranasal odorant concentrations of butane-2,3-dione (or butanedione, commonly known as diacetyl) at the interior naris and the olfactory cleft. Volunteers (n=12) were asked to perform different modes of sniffing in relation to the sniff intensity that were categorized as 'normal', 'rapid' and 'forced'. The highest concentrations of butanedione at both positions in the nose were observed during normal sniffing, with the lowest concentrations correlating with periods of forced sniffs. This corresponded to the panelists' ratings that normal sniffing elicited the highest odor intensities. These feasibility assessments pave the way for more in-depth analyses with a variety of odorants of different chemical classes at various intranasal positions, to investigate the passage and uptake of odorants within the nasal cavity., (Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.)

The olfactory and trigeminal systems play a role in the sensation of odors. The intrinsic optical signal (IOS) imaging method allows visualization of the neuronal activity. The IOS was measured after the nasal epithelium had been exposed to olfactory (H(2)S) and trigeminal (CO(2)) stimuli. The IOS was measured in the area of the middle turbinate. The response patterns of H(2)S and CO(2) on the middle turbinate were different, and some overlap between regions of activation was also observed. The response to CO(2) (20%) on the medial side of the middle turbinate was significantly higher than the response on the lateral side. In contrast, the response to H(2)S (5.6 ppm) was greater on the lateral side than on the medial side. There were no significant differences in response between the medial and lateral sides of the middle turbinate to stimuli of lower concentration (H(2)S 2.8 ppm, CO(2) 5% and 10%). These data suggest that the middle turbinate has regions which are sensitive to both olfactory and trigeminal stimuli., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Sex differences in olfactory sensitivity have been reported since the late 1800's with women typically outperforming men on tests of odor detection, discrimination or identification. It is not known whether women adapt differently than men to olfactory and trigeminal stimuli. Seventeen healthy volunteers participated (9 female, 8 male, mean age 22 years) in the study. As established by an odor identification test (UPSIT, score > or =38) all subjects had normal olfactory function. Event-related potentials (ERPs) were recorded in response to olfactory (25% v/v phenyl ethyl alcohol) and trigeminal (44% v/v CO(2)) stimuli using a computer controlled olfactometer (flow 8 L/min; stimulus duration 200 ms). Stimuli were applied at four intervals (5, 10, 20, and 60 s). Amplitudes and latencies of ERP peaks P1, N1, and P2 were measured. Stimulus intensity also rated using visual analogue scales subjects. When compared to phenyl ethyl alcohol, the slightly more intense CO(2) produced larger amplitudes and shorter latencies. Both, ratings and ERP amplitudes P2 decreased with decreasing interval between stimuli. Responses to the trigeminal and olfactory stimuli changed similarly in relation to repetitive stimulation. Women had larger ERP amplitudes P2. No sex-related difference for ratings and ERP in relation to repeated stimulation amplitudes was observed. Although women exhibit larger ERP amplitudes to chemosensory stimuli compared to men, the present data indicate on both psychophysical and electrophysiological levels that there is no major difference between young, healthy men and women in relation to short-term adaptation to suprathreshold chemosensory stimulation.

Using the intrinsic optical signal the present study aimed to investigate changes in blood flow at the nasal epithelium in response to specific olfactory stimulation. Recording equipment included an endoscope, a CCD camera, and a light source of 617 nm. Two concentrations of the specific olfactory stimulant H(2)S (2.8 and 5.6 ppm), generated by a computer-controlled olfactometer, were used for olfactory stimulation. Eight healthy normosmic volunteers participated. Using 5.6 ppm H(2)S stimuli, responses were typically recorded from the olfactory cleft, middle turbinate, and middle meatus while responses were less pronounced for 2.8 ppm H(2)S stimuli. Response areas were significantly larger for the 5.6 ppm H(2)S stimuli. While further experiments are needed, recordings of the intrinsic optical signal may be used to obtain responses from the nasal cavity to specific olfactory stimuli.