Page 48 - ACHEMS 2012 PROGRAM

daily food intake per 100 g body weight became greater in LNX
rats. Ambulatory activity was decreased, anxiety-related behaviors
during the activity test increased, time spent in the open arms
during elevated plus maze test decreased, and immobility duration
during Porsolt swim test increased in LNX rats compared with
sham rats. Dopamine contents in the hippocampus, nucleus
accumbens, and the mid-brain dopamine neurons were decreased in
LNX rats compared with sham rats. Results suggest that aberration
of oral sensory relay to brain may lead to the development of
depression- and anxiety-related disorders, and decreased
dopaminergic activity in the brain regions play a role in its
underlying mechanism. Acknowledgements: Supported by the
21st Century Frontier Research Program (2009K001269) and the
NRF (2010-0003642) funded by MOEST
#P60 POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Mixture suppression of sweet and umami taste by quinine in
the mouse brain: Implications for taste coding
John D Boughter, Kenichi Tokita
University of Tennessee Health Science Center/Department of
Anatomy & Neurobiology Memphis, TN, USA
Sweet and bitter-tasting compounds produce opposite patterns of
ingestive and aversive taste reactivity. Previous studies in rodent
taste nerves or brainstem neurons have shown that quinine has a
suppressive effect on the neural response to sucrose. This is likely
dependent on the TRPM5 channel in taste cells (Talavera et al.,
2008). We have recently demonstrated that sucrose and a
“synergistic” mixture of MPG and IMP evoke highly similar
patterns of neural activity in the mouse parabrachial nucleus
(PBN). In this experiment, we extend these findings by assessing
the potential suppressive effects of quinine on the response to
sucrose, MPG, IMP or an MPG-IMP mixture. We recorded
extracellularly from 70 mouse PBN neurons in response to a total
of 15 taste stimuli, including quinine mixtures. Quinine effectively
blocked the response to sucrose and the MPG-IMP mixture in
neurons characterized as sucrose-best (S-best), as well as in NaCl-
best neurons highly responsive to sucrose, but not in other neuron
types. However, the suppressive effect on sucrose was greater than
the effect on the MPG-IMP mixture. The residual response in this
case is likely to due to other, non T1R- or TRPM5-dependent
transduction mechanisms for umami stimuli. Multi-dimensional
scaling analysis showed that when sweet or umami-tasting stimuli
are mixed with quinine, they cluster with quinine in the 3-
dimensional “taste space”. Reconstruction of recording sites
support quality-based topography in the PBN, with S-best cells
occurring preferentially either in the medial or waist region, while
Q-best and N-best cells were most often recorded in lateral
subnuclei. Acknowledgements: NIH DC000353 (J.D.B.)
#P61 POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Taste responses of simultaneously recorded parabrachial and
cortical neural ensembles in awake rats
Madelyn A. Baez-Santiago2,4, Emily Reid1, Anan Moran1,
Yasmin Marrero1, Donald B. Katz1,2,3
1Brandeis University/Psychology Waltham, MA, USA,
2Brandeis University/Neuroscience Program Waltham, MA, USA,
3Brandeis University/ Volen Center for Complex Systems Waltham,
MA, USA, 4Brandeis University/Biology Waltham, MA, USA
Taste neurons in the rodent parabrachial pontine nuclei (PbN) take
almost direct input from the mouth, and are capable of controlling
some basic taste-driven behaviors. Thus it is reasonable to assume
that PbN taste responses might reflect activation of taste cells on
the tongue in a simple manner. However, these neurons also receive
strong feedback from forebrain regions such as gustatory cortex
(GC), which has been shown to respond to tastes with complex
“temporal codes” that signal first the presence, then identity, and
finally the palatability of tastes (Katz et al 2001, Grossman et al
2008, Sadacca et al, under review). Therefore it is also reasonable
to suggest that PbN taste responses may reflect this strong
feedback, in the form of similarly complex temporal codes. In order
to determine whether PbN taste responses reflect simple ascending
information, complex descending information, or both, I recorded
taste responses of multi-site PbN/GC single-neuron ensembles in
conscious female long evans rats (n=11). Rats received 40 μl
aliquots of 0.1 M NaCl, 0.01 M citric acid, 0.0001 M quinine HCl,
0.05 M sucrose passively delivered via interoral cannulae. Analysis
of these data demonstrates that approximately 32% of PbN neurons
respond distinctly to different tastes in the time domain, a
percentage similar to that observed in simultaneously recorded GC
neurons. Furthermore, we observed evidence that PbN taste
responsive neurons may actually be more temporally complex than
those in GC, changing rates at a time point amidst one of the
previously-described GC “epochs.” These results help to clarify
how taste processing occurs in real time, and also shed light on the
processing performed in any sensory system characterized by
extensive feedback from forebrain to early relays.
Acknowledgements: NIH T32 NS007292 NIH/NIDCD
RO1DC007703
#P62 POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Characterization of gustatory event related potentials related
to salt and sweet quality
Anna-Luisa Bartmuss, Thomas Hummel, Neelima Gupta,
Emilia Iannilli
Smell & Taste Clinic, Department of Otorhinolaryngology,
Technical University of Dresden, Dresden, Germany
Dresden, Germany
Aim: The present study aimed to characterize the EEG-derived
event related potentials (ERPs) in response to salt and sweet
stimulation. We compared results from a classical approach with
those from a high spatial resolution model. Methods: An EEG
System with 128 electrodes was used to record ERPs. For the
classical approach 5 electrodes, corresponding to Cz, Fz, Pz, C3
and C4 positions, were extracted. The main ERP components were
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