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extracellular recordings from the OT and PCX of anesthetized
mice. We found a wealth of similarities between structures,
including odor-evoked response magnitudes, breadth of odor
tuning, and odor-evoked firing latencies. In contrast, only few
differences between structures were found, including spontaneous
activity rates and odor signal-to-noise ratios. These results suggest
that despite major anatomical differences in innervation by
olfactory bulb mitral/tufted cells, the basic features of odor
representation and processing, at least within this limited odor
screen, are similar within the OT and PCX. We predict that the
olfactory code follows a distributed processing stream in
transmitting behaviorally and perceptually-relevant information
from low-level stations. Acknowledgements: Supported by grant
IOS-1121471 to D.W.W. and D.A.W. from the National Science
Foundation and DC003906 to D.A.W. from the National
Institutes of Health.
#P231
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
Dreaming of Odors: Odor Replay During Slow Wave Sleep
Enhances Memory
Dylan C Barnes
1,2
, Julie Chapuis
2,3
, Donald A. Wilson
1,2,3
1
CUNY/Cognitive Neuroscience New York City, NY, USA,
2
NKI/Emotional Brain Instiute Orangeburg, NY, USA,
3
NYU
Langone School of Medicine New York City, NY, USA
Post-training slow wave sleep (SWS) may contribute to memory
consolidation by allowing replay during a time of reduced sensory
input and possibility of interference. Here, by using precise
spatiotemporal patterns of electrical olfactory bulb stimulation as
the CS+ and CS- during differential odor-fear training, we tested
the replay hypothesis of SWS, by applying replay CS+ stimuli
during either SWS or waking during the immediate post-training
period. We used an electrical odor (e-odor) paradigm utilizing
electrical stimulation of various locations in the olfactory bulb
(OB) as conditioning stimuli in a differential odor-fear conditioning
task. We recorded local field potentials from the anterior piriform
cortex (aPCX) in behaving animals during fear conditioning and
ensuing sleep. Rats were chronically implanted with electrodes in
the aPCX and two stimulating electrodes in the OB. After recovery,
the rat was placed in a conditioning box for 30 min on three
baseline days, differentially conditioned with 5 CS+
e-odor/footshock and 25 CS- e-odor stimuli on the 4
th
day, and
tested with 5 CS+ and CS- stimuli on the 5
th
day in a new
context. CS+ and CS- were delivered (100Hz, 4 pulse trains, 160ms
inter-train interval, 2 sec total stimulation) via different electrodes
located 1mm apart in the OB. During the 4 hours post-training at
least 20 CS+ stimuli were delivered during either SWS or waking,
as monitored with EEG and EMG. On the test day, freezing
responses to the CS+ and CS- were examined. The results suggest
that CS+/CS- e-odor stimulation supports differential fear
conditioning. Furthermore, CS+ e-odor stimulation during post-
conditioning SWS enhances fear memory, while the same
stimulation during waking slightly reduces (extinguishes) memory
— consistent with odor replay during SWS. Acknowledgements:
NIDCD, DC03906
#P232
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
Functional connections of the medial amygdala and response
to chemosignal salience
Michael Meredith, Lindsey Biggs, Ariel Simonton, Ioana Stroe
Florida State University Tallahassee, FL, USA
In rodents, the vomeronasal organ detects conspecific and
heterospecific chemosensory signals and relays information to the
accessory olfactory bulb and medial amygdala. The anterior and
posterior medial amygdala (MeA, MeP) project to preoptic and
hypothalamic areas involved in social behavior. In mice, immediate
early gene FRAs expression in MeA increases for conspecific and
heterospecific stimuli. In MeP, conspecific reproductive stimuli
increase FRAs expression in the dorsal division, while a predatory
heterospecific stimulus activates the ventral division. Similar
results are seen in hamsters, although a response to predatory odors
has not yet been identified. The main intercalated nucleus (m-ICN),
a group of mostly GABAergic neurons lateral to MeP, may
modulate MeP activation, preventing response to non-relevant
stimuli. For heterospecific stimuli, the hamster m-ICN is active
while MeP is suppressed and the inverse is true for responses to
some conspecific stimuli. Responses in medial amygdala may
represent an evaluation of chemosensory signals, categorizing
stimuli based on salience. The immediate early gene expression
data suggest m-ICN is involved in shaping MeP response.
Preliminary slice electrophysiology results also suggest a functional
connection between m-ICN and MeP, in that stimulation of m-ICN
leads to inhibition of MeP neurons. Given that MeP activates for
unlearned relevant odors, changing the relevance (with
conditioning) may change activation within MeP and modulation
by m-ICN. Basolateral amygdala (BLA) is known to be activated
by conditioned odors and can be used as a positive control.
Preliminary results confirm the established effect of training in
BLA and suggest odor conditioning may decrease MeP activation.
Acknowledgements: Supported by NIDCD grants R01-DC005813,
T32-DC000044 and FSU Neuroscience Program Fellowship
#P233
POSTER SESSION VI:
OLFACTION CNS; TASTE PERIPHERY &
CNS; MULTIMODAL RECEPTION
Short-term Synaptic Plasticity Contributes to Differential
Cortical Population Responses to LOT Stimulation that
Mimics Passive or Active Respiratory Frequencies
Anne-Marie M. Oswald
1,2
, Nathaniel N. Urban
1
1
Department of Biological Sciences, Center for the Neural Basis
of Cognition, Carnegie Mellon University Pittsburgh, PA, USA,
2
Department of Neuroscience, University of Pittsburgh
Pittsburgh, PA, USA
This study focuses on how short-term plasticity at synapses
between mitral/tufted (M/T) cells and cortical neurons influences
population activity in the piriform cortex. We are particularly
interested in population responses to LOT stimulation at timescales
that mimic olfactory bulb input during passive breathing or active
sniffing. We hypothesize that LOT stimulation using burst stimuli
(40 Hz) delivered at 2 Hz (passive breathing) or 8 Hz (active
sniffing) produces differential population responses. Furthermore,
these differences are correlated with the type of short-term
plasticity expressed at M/T-to-cortical neuron synapses. To assess
population activity, piriform cortex slices (n=13) were loaded with
the calcium indicator, Oregon Green Bapta-1. The slices were then
104 | AChemS Abstracts 2012
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