Abstracts - Association for Chemoreception Sciences

#P241 POSTER SESSION V:
CENTRAL OLFACTION; CHEMOSENSORY
PSYCHOPHYSICS & CLINICAL STUDIES
Measuring referral of retronasal odors: The effect of taste
Barry Green 1,2 , Karen Blacher 1 , Danielle Nachtigal 1
1
The John B. Pierce Laboratory New Haven , CT, USA,
2
Yale School of Medicine New Haven, CT, USA
Referral of odors to the oral cavity is a fundamental phenomenon
of flavor perception, yet the mechanism of referral remains poorly
understood. A major impediment to understanding has been the
absence of a method to measure referral. The aims of the present
study were to use a novel psychophysical procedure to measure
the perceived location of retronasal odors and to assess the role of
taste stimulation in producing or augmenting referral. After
sipping and spitting 5-ml aqueous solutions of citral (0.00025%)
or vanillin (1.8 mM), Ss breathed normally through the nose and
made natural tasting movements as they drew the perceived
locations of odors on a diagram of the nasal and oral cavities using
Microsoft Paint. The effect of taste was studied by comparing
localization when the odorants were presented alone or with
sucrose (0.56 M) or NaCl (0.32 M). With 17 Ss tested the results
show that when perceived alone, vanillin and citral are localized
about equally often to the nose (61% and 67% of trials) and to the
oral cavity above the tongue (52% and 68% of trials), but much
less frequently to the tongue itself (29% and 38% of trials). When
the odorants were mixed with sucrose, the frequency of
localization to the tongue more than doubled (71% and 79%),
while the frequency of localization to the nose declined (46% and
57%). Notably, when the odorants were mixed with NaCl,
localization was unchanged from the odorants alone. Thus,
referral to the mouth can occur, albeit incompletely, in the absence
of a specific taste or somatosensory stimulus, but referral to the
tongue depends strongly upon the presence of a congruent taste.
These findings have implications for the neural mechanism of
retronasal referral, particularly for how odors and tastes become
co-localized on the tongue. Acknowledgements: Supported by
NIH grant RO1 DC005002
#P242 POSTER SESSION V:
CENTRAL OLFACTION; CHEMOSENSORY
PSYCHOPHYSICS & CLINICAL STUDIES
A Modest Influence of Response Bias on the Enhancement
of Taste-Like Properties of Odors
Sarah Nolan-Poupart 1 , Barry Green 1,2 , Maria G. Veldhuizen 1,2 ,
Jessica Blanton 1 , Dana M. Small 1,2
1
John B. Pierce Laboratory New Haven, CT, USA,
2
Yale University New Haven, CT, USA
Prior work has shown that odors come to be rated as smelling
more like tastes with which they have been experienced. There is
some question, however, regarding whether this effect can be
attributed to perceptual learning vs. response bias. For example,
one could observe a “halo effect” where rating one attribute (e.g.
pleasantness) may influence the rating of the subsequent attribute
(e.g. sweetness), or a “dumping effect” where the absence of a
measure for a particular attribute results in the subject “dumping”
that attribute into another response category. The current
investigation aimed to determine the possible roles of these two
response biases in the so-called acquisition of taste-like properties
by odors. In experiment 1 we examined halo effects. 12 subjects
were exposed to a target odor mixed with a sweet solution (0.3 M
sucrose) and a non-target odor mixed with water. Subjects rated
the odors before and after exposure for intensity, familiarity,
sweetness and pleasantness. The order of the ratings was
counterbalanced and the effect of order on the predicted increase
in odor sweetness rating was examined. We found that sweetness
ratings increased for the odor paired with the sweet solution but
not for the odor paired with water. Sweetness enhancement was
greater when order was included as a covariate. In experiment 2
we are examining dumping by testing whether inclusion of a scale
in which subjects can rate “other” aspects of the sensation
influences the enhancement of taste-like qualities of odors by
taste. Preliminary data show that enhancement occurs irrespective
of whether the “other” category is available. Taken together these
findings support the view that the enhancement of taste-like
qualities in odors represents perceptual learning, but may also be
augmented by halo effects. Acknowledgements: Firmenich
#P243 POSTER SESSION V:
CENTRAL OLFACTION; CHEMOSENSORY
PSYCHOPHYSICS & CLINICAL STUDIES
Not all Formulas are Alike: Differential Growth
Patterns among Infants Fed Protein Hydrolysate or Cow
Milk-Based Formulas
Alison K. Ventura, Laura D. Lukasewycz, Sara M. Castor,
Gary K. Beauchamp, Julie A. Mennella
Monell Chemical Senses Center Philadelphia, PA, USA
The rate of growth during infancy is a predictor of later obesity
risk. Thus, interventions aimed at preventing obesity should begin
during infancy when children are fed predominantly milk-based
diets. Because of the striking differences among formulas,
specifically the higher protein and amino acid content of protein
hydrolyzed formulas (PHF) compared to cow milk-based
formulas (CMF), we hypothesized that infants fed PHF would
consume less formula and show slower rates of growth across
infancy. To this end, we conducted a clinical trial in which infants
whose mothers had decided to formula feed were randomized to
feed either CMF (n=32) or PHF (n=24) from 0.5 to 7.5 months.
Infants were weighed and measured monthly, then videotaped
feeding their assigned formula under naturalistic conditions.
Multilevel linear growth models were employed to compare
trajectories for anthropometry and intake. Although there were
no group differences at study entry, CMF infants had significantly
higher weight-for-age and weight-for-length z-scores across ages
2.5- 7.5 months and significantly greater change in weight-for-age
z-scores across ages 1.5-7.5 months compared to PHF infants.
Infants fed CMF consumed more formula to satiation than infants
fed PHF throughout the study. That there were no differences in
infant acceptance or maternal rating of infant enjoyment at any
age suggests that the slower growth rate of PHF infants cannot be
attributed to rejection of the flavor of PHF. In conclusion, infants
fed PHF satiated faster than infants fed CMF and the ensuing
decreased intakes resulted in more normative growth trajectories.
Whether the enhanced satiating effect of PHF is attributable to its
higher protein content, amino acid distribution, or some other
metabolic effect is an important area for future
research. Acknowledgements: The project described was
supported by Award Number R01HD37119 from the Eunice
Kennedy Shriver National Institute of Child Health and Human
Development. The content is solely the responsibility of the
authors and does not necessarily represent the official views of the
Eunice Kennedy Shriver National Institute of Child Health and
Human Development or the National Institutes of Health.
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