Basic HTML Version
20 | AChemS Abstracts 2012
Abstracts are printed as submitted by the author(s)
humanized Channelrhodospin-2 (hChR2) in all olfactory sensory
neurons (OSNs), we have developed a novel technique for
precisely controlling both the spatial and temporal aspects of OSN
input within the olfactory bulbs of freely moving mice. This
technique involves optically stimulating OSN axon terminals and
making tetrode recordings from mitral and tufted (MT) cells in the
ventral aspect of the olfactory bulb. We show that by adjusting the
power output of the LED coupled to the optical fiber, patterns of
OSN activation with various spatial extents can be created in the
olfactory bulb. Further, the patterns of OSN input can be adjusted
such that the activity of the recorded MT cells contains information
adequate to discriminate between the OSN input patterns. We
demonstrate the use of this technique to examine the effect that
ongoing bulbar activity has upon the ability of populations of
simultaneously recorded MT cells to discriminate between spatial
patterns of OSN input. We also report results from experiments in
freely moving mice regarding the impact that behavioral state has
upon MT responses to precisely controlled olfactory stimuli.
Acknowledgements: NIDCD F32DC011980 (DG), R01DC009640
(TB), R21DC010911 (TB), the Whitehall Foundation and the Brain
Research Foundation (TB), the Boettcher Foundation’s Webb-
Waring Biomedical Research Program (GF), NIDCD R01DC00566
(DR), P30DC04657 (DR).
#32
PLATFORM PRESENTATIONS —
POLAK YOUNG INVESTIGATOR AWARD WINNERS
Neuronal population state dynamics changes in taste processing
following emotional learning
Anan Moran, Donald B Katz
Department of Psychology and the Volen Center for Complex
Systems Waltham, MA, USA
A bad experience with an unfamiliar dish can cause us to avoid that
for a long time thereafter. Gustatory cortex (GC) plays a significant
role in driving this effect of experience on behavior, but the manner
in which GC ensemble taste processing is altered during this
process is not fully understood. Here, we investigated this question,
basing our work on recent studies showing that ensembles of GC
neurons respond to taste delivery with coherent sequences of states,
each uniquely defined in terms of the set of firing rates across the
neuronal ensemble, that repeat reliably across trials, but with a
variable time course. We recorded multiunit activity from the GC
of rats, holding a subset of neurons across a conditioned taste
aversion (CTA) and extinction protocol, whereby rats first learned
to associate a taste (CS) with malaise (US) and then learned that the
CS was again safe. The protocol was optimized to alter the
emotional value of an initially palatable taste twice in quick
succession, while leaving its sensory characteristics unchanged.
Hidden Markov Model (HMM) analysis of the neuronal data then
revealed the putative underlying state transition timings. These
analyses demonstrated that following CTA GC ensembles jump into
state sequences earlier, and progress through those state sequences
more quickly (the durations of states became shorter) and sharply
(transition times between states got shorter). Following extinction
these changes were relaxed back towards pre-CTA values.
Altogether our findings suggest that CTA somehow “primes”
networks in GC to process tastes more quickly.
Acknowledgements: This work is funded by R01 DC-6666
and the Swartz Foundation
#33
PLATFORM PRESENTATIONS —
POLAK YOUNG INVESTIGATOR AWARD WINNERS
Volatile Inhibitors and Activators of the Carbon
Dioxide-Sensitive Neuron as a New Generation of
Mosquito Control Agents
Dyan MacWilliam
1
, Sean M Boyle
2
, Anandasankar Ray
1,2
1
University of California, Riverside/Entomology Riverside, CA,
USA,
2
University of California, Riverside/Genetics, Genomics and
Bioinformatics Program Riverside, CA, USA
Carbon dioxide (CO
2
) present in our exhaled breath is an important
sensory cue for blood-feeding mosquitoes, causing activation of
long-distance host-seeking and an increased responsiveness to
human skin-odors. CO
2
is used as the primary lure in mosquito
traps in the developed world, but generating CO
2
is expensive and
impractical for use in developing countries where vector borne
diseases cause millions of deaths each year. The identification of
affordable and safe chemicals that can either activate or inhibit the
CO
2
receptor neuron could enhance the control of disease
transmitting mosquitoes. CO
2
is detected by 7-transmembrane
receptors (Gr1,3) expressed by neurons in peg-sensilla of the
mosquito maxillary palp. Using structural similarity measurements
to known agonists and antagonists, we performed a novel chemical
informatics screen of >400,000 chemicals to predict novel CO
2
receptor ligands. We selected 139 of these chemicals and tested
them for activity using single sensillum recordings from the
mosquito,
Aedes aegypti
. We found that over 20% of the predicted
compounds increase activity of the CO
2
receptor neuron
substantially. The strongest activators (>100 spikes/sec) were tested
in both
Aedes
and
Culex quinquefasciatus
, and results indicate a
conservation of response across species. We identified several
compounds that decreased responsiveness to CO
2
when odor pulses
were overlaid on a background of a longer CO
2
stimulus. The top
two inhibitors decreased activity by 60 and 83%. Several of these
newly identified activators and inhibitors are pleasant-smelling to
humans and are already approved for use as flavor and fragrance
agents. These odors are being tested in both laboratory and semi-
field conditions for their potential use as agents in a new generation
of mosquito control. Acknowledgements: RO1 grant from
NIAID (NIH)
#35
WORKSHOP:
RESEARCH CAREERS IN INDUSTRY
Round-table Q&A session with all the speakers and audience
Workshop attendees are eligible to attend the Social with workshop
speakers and ChEMA members
O R A L A B S T R A C T S