Abstracts - Association for Chemoreception Sciences

allows visualization and quantification of the interneuron cell
bodies throughout the bulbar layers of the AOB (Krosnowski
et al, 2012). We found significant differences in the number of
cholinergic interneurons in the anterior and posterior glomerular
layer (GL) and the external plexiform layer (EPL), with the
highest numbers of cholinergic interneurons in the anterior GL
and posterior EPL. In the posterior EPL, we also noted a high
density of GFP+ cells forming a ring around the outer edges
of the layer, thus creating a heavy GFP+ population along
the border between the anterior and posterior AOB. We then
examined the possible role of ChAT interneurons in the AOB
using adult male mice exposed to either bedding from a mated
pair or to a male aggressor mouse. We monitored the activity
marker, c-fos, in these regions and found significantly higher
levels of activation of ChAT-expressing cells in the EPL in both
exposure groups when compared to activation in control mice,
suggesting that this population may serve a role in the processing
of social odor cues. Thus, we have identified a significant
cholinergic interneuron population in the AOB that varies
significantly in the anterior and posterior regions. Thus, our data
supports the idea that the anterior and posterior AOB process
sensory information differently and suggests that this cholinergic
interneuron population may serve to process olfactory
information in a region specific manner. Acknowledgements:
Supported by research grants NIH/NIDCD 009269, 012831 and
ARRA administrative supplement to WL
#P87 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Suppression of Association Synapses in Piriform Cortex
During Post-Training Sleep Impairs Odor Memory Selectivity
Dylan C Barnes 1,2 , Donald A Wilson 1,2,3
1
Graduate Center CUNY New York City, NY, USA, 2 Nathan Kline
Institute Orangeburg, NY, USA, 3 NYU Langone Medical Center New
York City, NY, USA
Slow wave sleep (SWS) is characterized by slow-wave
oscillations in neocortex, as well as sharp waves (SPW) in
both the hippocampus and piriform cortex (PCX). Neural
activity during SWS is hypothesized to contribute to memory
consolidation through “replay” of waking activity patterns. For
example, we have demonstrated that imposed replay of odorevoked
activity in the olfactory system during SWS enhances
subsequent memory of that odor. Neurons co-activated by an
odor are hypothesized to become linked into a cohesive ensemble
through strengthening of association synapses. Replay of odor
evoked ensemble activity during SWS may help strengthen
these connections and improve memory and memory acuity.
Here, we tested the hypothesis of that association fiber activity
during SWS facilitates replay and memory of recently learned
odors by infusing baclofen (or saline) into the PCX during posttraining
sleep. Baclofen is a GABA-B receptor agonist that has
been shown to selectively depress association fiber synapses.
Rats were chronically implanted with bilateral cannulae and
a recording electrode in the anterior PCX. After recovery, rats
were differentially conditioned with CS+ odor/footshock and
CS- odor stimuli. During the 4 hours immediately post-training,
animals were placed in a sleeping chamber and bilaterally
infused with either baclofen or saline. Local field potential
and EMG activity were recorded during conditioning,
post-training sleep, and test periods. On test day, 24 hours
following conditioning, freezing responses to the CS+, CSand
other odors were examined. Preliminary behavioral results
suggest that post-training PCX baclofen infusions do not
impair memory for the CS+ but reduce odor acuity/enhance
generalization of the odor-fear response. Acknowledgements:
F31-DC012284 to D.C.B. and R01-DC003906 from the
NIDCD to D.A.W.
#P88 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Cholinergic modulation of glomerular odor sensitivity
in the olfactory bulb
Mounir Bendahmane, M Cameron Ogg, Max L Fletcher
University of Tennessee Health Science Center Memphis, TN, USA
In the olfactory system, many studies have shown that
cholinergic input to the olfactory bulb is not only involved in
learning and memory but also detection and discrimination.
In this study we used calcium imaging to explore the cholinergic
effect on OB postsynaptic glomerular odor responses. Using mice
expressing GCaMP2 in M/T cells, we studied the modulation
of dorsal surface glomerular odor concentration-response
curves via HDB (horizontal limb of the diagonal band of Broca)
stimulation or OB cholinergic pharmacological manipulation.
Overall, we find that increased cholinergic OB activation through
HDB stimulation or cholinergic-uptake blocker application
increases the sensitivity of individual glomerular odor responses
by shifting the odor concentration-response curve to the left and
decreasing the EC50 by up to one log unit in odor concentration.
This effect was observed for all glomeruli tested regardless
of baseline odor sensitivity or odorant used. OB application
of a muscarinic antagonist completely blocks these shifts,
suggesting that the increased sensitivity observed is primarily
driven by muscarinic activation. We are now exploring the
cholinergic effects on individual OB cell types using two-photon
microscopy to further address these effects at the single cell level.
Acknowledgements: NIH R03 DC009853 and the Pew Scholars
Program in the Biomedical Sciences.
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
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