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#P252
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
Olfactory sensing of glutamate and its modulation by
hunger and satiety signals in humans
Jennifer Chen
1
, Denise Chen
2
1
Psychology Department, Rice University Houston, TX, USA,
2
Neurology Department, Baylor College of Medicine
Houston, TX, USA
Monosodium glutamate (MSG), a derivative of glutamate acid and
a naturally occurring nutrient, contributes to umami, one of the five
basic tastes, and signals amino acids. While glutamate plays an
important role in taste, little is known about its role in olfaction.
A special class of glutamate receptors has been identified as
olfactory receptors in the fruit fly and the Protostomia but whether
it exists in other animals is not known. Using triangular triple-
forced-choice discrimination tasks, we show that MSG (≥99%,
Sigma-Aldrich) dissolved in purified water has an olfactory
property that is detectable by the nose. Moreover, olfactory sensing
of MSG is independent of either retronasal olfaction or trigeminal
stimulation. We subsequently assess subjects’ olfactory threshold of
MSG, several other tastants, and a non-tastant control, both after
fasting and after satiation. We show a significant enhancement of
olfactory sensitivity following fasting that is unique to MSG.
Taken together, our findings show that basic tastes carry orthonasal
olfactory properties and offer the tantalizing evidence that olfactory
glutamate receptors also operate in humans.
#P253
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
The roles of congruency and nutritive vs. non-nutritive tastes
in taste-odor interactions
Juyun Lim, Tomomi Fujimaru
Oregon State University, Department of Food Science
Corvallis, OR, USA
Previous studies in our laboratory have shown two types of taste-
odor interactions: odor enhancement by taste and odor referral to
the mouth. The study findings have suggested that the presence
of a nutritive taste that is also congruent with an odor is a necessary
condition for both phenomena. However, the previous studies used
odors that were primarily congruent with a nutritive (sweet or salty)
taste. The present study therefore investigated the role of the
nutritive status of tastes in both taste-odor interactions using odors
that are congruent with a non-nutritive taste (bitter or sour). Coffee
and citrus odors were presented alone or with sucrose, CA, or
caffeine. In three separate sessions, 24 Ss 1) rated the perceived
intensities of sweetness, sourness, bitterness, and specific odor in a
sip-and-spit procedure; 2) reported the perceived locations of odors
after inhaling odors through the mouth alone or in the presence of
either water or tastes in the mouth; and 3) rated the congruency of
tastes and odors. The results showed that only sucrose significantly
enhanced the perceived intensities of citrus and coffee odors
(Tukey test,
p
<0.05), while other tastes (caffeine, CA) failed to
enhance or even suppressed the odors. However, congruent tastes
significantly increased localization of odors to the tongue (χ
2
,
p
<0.05), independent of nutritive status. These findings suggest that
taste-odor congruency is a necessary but not sufficient condition for
retronasal odor enhancement. In contrast, taste-odor congruency is
the only requirement for retronasal odor referral, and the degree of
congruency modulates the degree of odor referral to the mouth. The
implications of the study findings will be discussed in terms of the
cognitive and perceptual factors of flavor perception.
#P254
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
Influence of Color and Viscosity on Milk Pleasantness and
Intensity Ratings in Disordered Eaters
Mark Sappington, August Capiola, Michael Seals,
Bryan Raudenbush
Wheeling Jesuit University Department of Psychology
Wheeling, WV, USA
While previous research on viscosity and taste perception tends to
be in agreement, the research on color and taste perception exhibits
a tremendous amount of inconsistency. Possible reasons for this
inconstancy are the multi-modal nature of gustation and possible
confounds, such as level of disordered eating, which are rarely
accounted for. The purpose of the present study was to evaluate the
effect of both color and viscosity on the pleasantness and intensity
ratings of milk, while taking level of disordered eating into
account. Thirty-eight participants (22 male, 16 female) completed
the study. The stimuli were distinct milk samples which varied in
color (red, blue, brown, white) and viscosity (skim, 2%, whole),
which led to 12 possible combinations. Food-neophobics (those
individuals who are unwilling to try new foods) rated milk as less
pleasant and more intense, as well as consumed less of it, when
compared to food-neophilics (those individuals who are particularly
willing to try new foods). However, the significant pleasantness
and intensity ratings were found to disappear when Food
Neophobia Score was used as a covariate, suggesting that
significance within the data relied upon whether an individual was
classified as food-neophilic or food-neophobic. While this does not
provide an all-inclusive explanation for the past ambiguity, it does
open up a new direction for future research on the multi-modal
influences of taste perception where level of disordered eating
should remain a covariate.
#P255
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
Trigeminal stimuli influence perception of olfactory stimuli
Valentin A Schriever, Volker Gudziol
Smell & Taste Clinic Department of Otorhinolaryngology
University of Dresden Medical School Dresden, Germany
Although most common odors target both, the olfactory and the
trigeminal system, little is known about the influence of the
trigeminal system on the perception of olfactory stimuli. With this
in mind we examined the influence of a pure trigeminal (CO2)
stimulus on the intensity perception of a pure olfactory stimulus
(PEA). The stimuli were presented in pairs (containing a CO2 and a
PEA stimulus) using the Burghart olfactometer OM6.b. Duration of
one stimulus was set to 400ms. Forty normosmic subjects, 29
female, 11 male, age range: 20-32 years (mean: 24.95 SD 3.13)
participated in the study. To ensure that subjects were normosmic,
every subject was tested with the “Sniffin’ Sticks” 16 odor
identification test: range: 13-16 (mean: 14.60 SD 1.08). The study
consisted of three parts: Part one: Both stimuli were presented at
the same time. While the PEA stimulus was held constant the
Abstracts | 111
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