A new taste reactivity analysis of the integration of taste and
physiological state information.
Grill, Harvey J., Mitchell F. Roitman, and Joel M. Kaplan.
University of Pennsylvania, Graduate Groups of Psychology and
Neuroscience, 3815 Walnut Street, Philadelphia, Pa 19104
APStracts 3:0126R, 1996.
We used conjoint manipulation of taste and physiological state to
address the theoretical issue of signal integration. The interaction
between taste [glucose concentration] and state [food deprivation]
was evaluated using the taste reactivity method where oral motor
responses elicited by direct intraoral infusion is measured. The
timeframe of the typical taste reactivity paradigm, where observation
is limited to the infusion period, was expanded to include the post
-infusion interval. In each test session, rats received a series of
trials consisting of 15 sec intraoral infusions and 45 sec post
-infusion observation intervals. Two experiments were run in which
glucose concentration was varied and rats were run non-deprived and
after 24h food deprivation. In Experiment 1, glucose concentrations
[0, 3.2, 6.25,12.5 and 25%] were randomly presented during each test
session. In Experiment 2, individual glucose concentrations [0, 6.25
or 25%] were presented during separate sessions. For both, a
deprivation condition was flanked by non-deprived [baseline]
sessions. Concentration-response functions were comparable in both
experiments. In each experiment the shape of the concentration
-response function was dramatically different during and after
infusions. During infusions, there were no increases in glucose
-elicited rhythmic oral responses beyond a very dilute concentration.
After infusions, the concentration-response functions appeared linear
across the concentration range. In both experiments deprivation
elevated responding only in the after-infusion periods. In Experiment
1, the concentration-response function was uniformly elevated [on
average, 27 %] by deprivation, which if taken at face value would
suggest an additive combination of taste and state feedback signals.
In Experiment 2, however, deprivation increased responding [about
30%] for 6.25%, but not for 0 or 25%, suggesting a stimulus
specificity of the taste-state integration. Clearly then, the taste
-state profiles differed as a function of experimental design. In
Discussion, we suggest that the uniform elevation of responding to
all glucose concentrations, and to water, may be an artifact of the
random presentation of all stimuli during individual sessions.
Experiment 2, where stimuli were presented in a between-sessions
design, may provide a truer reflection of the underlying integrative
process.
Received 19 September 1995; accepted in final form 7 March 1996.
APS Manuscript Number R581-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96