There are three
ongoing lines of behavioral research in our laboratory:
The use of conditioned
taste aversions to characterize the detection thresholds and
discriminative capabilities for free fatty acids in a
Sprague-Dawley rat model.
we have demonstrated that rats can detect and avoid linoleic
acid and oleic acid during 2-bottle preference tests the day
after receiving a conditioned taste aversion (CTA) pairing
of the consumption of either linoleic or oleic acid followed
by an i.p. injection of lithium chloride which causes
gastric distress. We hypothesize that rats may be
using orosensory cues in the detection and avoid of the free
fatty acids. This project seeks to minimize the role
of olfaction and post-ingestive cues through short-stimulus
testing of licking behavior in the Davis Rig apparatus
following a CTA pairing with linoleic or oleic acid.
Use of short-stimulus (8-30s) testing allows the licking
behavior to multiple concentrations of the conditioned
stimulus as well as other potentially associated stimuli to
Click here to view our recent
publication that used this
methodology to identify the detection thresholds of free
fatty acids and the ability to form generalized avoidances
across free fatty acids.
The effect of
adding free fatty acids to other taste solutions on the
consumption patterns of appetitive and aversive taste
that rats can detect very small quantities (88 micromolar)
of linoleic acid and oleic acid, it is thought that these
free fatty acids may be a 'tastable' chemical component of
fats such as corn oil. Adding a fat (corn oil) to taste
solutions will increase the consumption of the solution by a
rat. The proposed transduction mechanism of free fatty acids
(delayed-rectifying potassium channels) would support the
hypothesis that free fatty acids may enhance the intensity
of concomitant taste stimuli. In this study, solution
intake is measured in a Davis Rig apparatus which has a
shutter that opens and closes to allow a discrete access
time, typically 8-30 seconds, during which the rat can lick
a bottle spout of up to 16 different solutions. A
computer controls the presentation of each solution and
measures the number of licks during each trial.
Click here to view our recent publication that established consumption
patterns for varied concentrations of appetitive (sweet) and
aversive (salty, sour, & bitter) tastants and then measured
the effect of adding free fatty acids to the taste
The effect of
the benzodiazepine chlordiazepoxide (CDP aka Librium) on the
ingestion of sweet, sour, salty, and bitter tastants.
Evidence suggests that benzodiazepines such as CDP act to
increase the palatability of taste stimuli. We are
exploring the effects of CDP administration on taste through
brief access (<30s) and long-term (>30min) stimulus testing
of sweet, sour, salty, and bitter taste solutions.
This research is a collaboration between the Pittman
laboratory at Wofford College and the laboratory of Dr. JP
Baird at Amherst College. Check back soon for updates on
this new line of research.
When we are collecting data, click here to view the live web
cam from inside the Davis Rig testing chamber!
Having shown that Sprague-Dawley rats can
detect and avoid free fatty acids following a CTA, we seek
to identify the afferent neural signals that permit this
detection and avoidance. One method of identifying
necessary and sufficient afferent neural pathways involves
compromising the system through selective nerve elimination.
We have begun a series of experiments combining the CTA
detection of free fatty acids with the systematic
elimination of the three gustatory nerves.
Click here to view our recent publication that implicates
the chorda tympani afferent taste nerve as transmitting
information about free fatty acids from the tongue to the
Representing the latest addition to our
facilities, we plan to commence neural recordings of
afferent gustatory signals during oral cavity stimulation by
free fatty acids. Preliminary evidence from our nerve
transection studies suggests that the chorda tympani nerve
plays a role in the ability of rats to avoid linoleic acid
following a CTA. Whole-nerve recordings of the
chorda tympani nerve combined with multi-unit and
single-unit recordings in the geniculate ganglion will be
used to characterize any afferent neural response to
linoleic acid stimulation of the oral cavity.
See our research facilities for additional information.