Abstracts - Association for Chemoreception Sciences

#P205 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
#P206 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
How do rabbit newborns and human adults perceive the
configuration in a 6-component blending odor mixture?
Sébastien Romagny, Thierry Thomas-Danguin, Gérard Coureaud
Centre des Sciences du Goût et de l’Alimentation (CSGA), UMR 6265
CNRS, UMR 1324 INRA, Université de Bourgogne, Flavour Perception
Team and Developmental Ethology and Cognitive Psychology Team
Dijon, France
Comparative studies give the opportunity to better understand
common and dissimilar processes in terms of perception,
cognition and behavior between organisms. Regarding the
elemental and configural perception of odor mixtures, newborn
rabbits and human adults present some similarities. In particular,
they both process a 6-component mixture (RC) in a weak
configural way, leading to the perception of a novel odor (e.g.,
red cordial in humans) in the mixture: in rabbits, neonates do
not respond to RC after learning of one component, while they
generalize for another mixture of same complexity; in humans,
the quality of the single odorants is judged as significantly
different to the mixture. Here, we set out to examine whether
the perception of the RC configuration strictly depends on the
quantity and/or the quality of the components. To that goal,
we carried out a generalization experiment in rabbit pups and
a similarity rating task in human adults, using several submixtures
of increasing complexity (i.e., 2, 3, 4 or 5 odorants). We
conditioned the pups to sub-mixtures and tested their behavioral
responsiveness to these stimuli compared to the full mixture
(RC). In humans, participants rated the similarity between
the sub-mixtures and RC. The results indicated that newborn
rabbits became able to respond to the RC mixture when they had
previously acquired at least 4 of its components, whatever their
odor quality. In human adults, similarity between sub-mixtures
and the RC mixture depended more on the odor quality of the
odorants included in sub-mixtures rather than on the number of
mixed odorants. Therefore, even if these two models shared a
configural perception of the same RC odor mixture, the factors
underpinning its perception seem to be different, at least in part.
The Contribution of the T1R1 Subunit to Taste Detection of
Glutamate as Behaviorally Assessed in a Murine Model.
Kimberly R Smith, Alan C Spector
Florida State University Tallahassee, FL, USA
Whether taste detection of L-glutamate is mediated solely
by the T1R1+T1R3 heterodimer or whether an additional
glutamate-sensing taste transduction mechanism(s) contributes
is controversial. Here, we behaviorally assessed the necessity
of the T1R1 subunit to taste detection of monosodium
glutamate (MSG) in a two-response discrimination procedure
using T1R1 knockout (KO) mice and their same-sex littermate
wild-type (WT) controls. Water-restricted mice were trained
to discriminate a tastant from water with a correct response
resulting in the delivery of a water reinforcer and an incorrect
response resulting in a time-out. Sensitivity to NaCl and MSG
was similar between genotypes. However, upon the addition
of the sodium channel blocker amiloride (100 µM) and inosine
5’ monophosphate (IMP), at a concentration (2.5 µM) shown
to potentiate the glutamate signal in a variety of assays,
performance of the KO mice to this MSG mixture (M+A+I) was
severely impaired. Whereas WT mice performed at consistently
high levels across concentrations, the ability of the KO mice to
detect the M+A+I solution was above chance only at the higher
MSG concentrations. The possibility that IMP was precluding
concentration-dependent performance in the WT mice to the
MSG in the presence of amiloride was confirmed when we
found that WT mice could detect 2.5 µM IMP alone with
relatively high accuracy, whereas KO mice could not respond
significantly above chance. Collectively, these results strongly
suggest that 1) the Na + ion dominates the taste detection of MSG
in mice consistent with other recent data from our laboratory,
and 2) glutamate may be activating a T1R1-independent highthreshold
receptor in the presence of IMP, but normal detection
of glutamate depends on the T1R1 subunit. Acknowledgements:
NIH R01-DC004574 (ACS) & NSF GRF to KRS
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
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