Abstracts - Association for Chemoreception Sciences

#17 PLATFORM PRESENTATIONS: OLFACTION
Sexual dimorphism and experience-dependent plasticity
in mouse vomeronasal neurons
Timothy E Holy, Pei S Xu
Washington University in St. Louis St. Louis, MO, USA
Male and female mice exhibit behaviors particular to their sex,
and these differences presumably reflect sexual dimorphism
in neuronal circuitry. However, in terms of neuronal anatomy
or function in the mouse, there are relatively few reported
differences males and females. Here we asked whether neurons
in the vomeronasal organ, a social odor- and pheromone-sensing
neuroepithelium, differed functionally between males and
females. We performed exhaustive high-speed calcium imaging
from intact vomeronasal epithelia in 26 imaging volumes from
male and female mice, measuring the responses of more than a
quarter-million individual sensory neurons. Using a battery of
sulfated steroids, a class of odors originally isolated from mouse
urine, we found that the large majority of responsive neuronal
types were found in equal abundance in both males and females.
However, we found restricted cases of clear sexual dimorphism,
including one neuronal type that was more than one-hundredfold
more common in males than in females, by far the
strongest dimorphism ever reported in the mammalian central
nervous system. We then explored the mechanism generating
this dimorphism. Surprisingly, male/female differences
depended entirely on the history of sensory experience, as
vomeronasal organs from males could be converted to a pattern
indistinguishable from females simply by prolonged exposure
to the odors of female mice. The finding that a strong neuronal
dimorphism is determined entirely by experience, in a sensory
system long believed to be devoted to “innate” responses,
raises important new questions about the roles of “nature”
and “nurture” in brain architecture. Acknowledgements:
NIH-NIDCD R01 DC005964 NIH-NINDS/NIAAA R01
NS068409 NIH DP1 OD006437
#18 PLATFORM PRESENTATIONS: OLFACTION
Reinforcement of Sexual Attraction through
Pheromone-Induced Associative Learning
Jane L Hurst, Sarah A Roberts, Emma Hoffman,
Amanda J Davidson, Lynn McLean, Robert J Beynon
University of Liverpool / Institute of Integrative Biology Liverpool,
United Kingdom
Scents play an integral role in mediating reproductive
interactions in many species, allowing animals to recognize
and locate individual conspecifics of the opposite sex, assess
their attractiveness and stimulate mating. The urine used by
male house mice to advertise their location and competitive
dominance contains many androgen-dependent volatiles together
with a high concentration of major urinary proteins (MUPs) that
bind and slow the release of these volatiles. Females that detect
airborne urinary volatiles are attracted to approach and sniff
the scent marks closely, but it is contact with an atypical malespecific
MUP named darcin that reliably elicits female sexual
attraction to spend time near male scent. Darcin will elicit this
attraction even in the absence of all other urinary components,
while male urine without darcin is no more attractive than
female urine. Importantly, though, darcin acts not only through
direct attraction to spend time near the pheromone itself. It is
also highly potent in stimulating associative learning such that
animals rapidly learn the same attraction towards the individual
airborne odor detected in association with darcin, targeting
attraction to a specific male. Darcin also rapidly conditions
preference for spatial cues associated with its location, such that
mice relocate and prefer to spend time in the site even when scent
is absent. This conditioned place preference is remembered for
approximately 14 days. Preference for multiple locations can be
remembered, while the relative amount of darcin in competing
male scents influences female conditioned preferences. This
reveals that pheromone-induced social learning can both
target and strongly reinforce female sexual attraction towards
individual males even though male mice all produce the same sex
pheromone. Acknowledgements: These studies were supported
by the Biotechnology and Biological Science Research Council
(BBC503897 and BB/J002631/1) and the Natural Environment
Research Council (NE/G018650), UK
#19 PLATFORM PRESENTATIONS: OLFACTION
Behavioral effects of bulbar neuromodulation
Christiane Linster, Sasha Devore, T Samuel Dillon, Olga Escanilla,
Matthew Lewis, Laura Manella
Cornell University Neurobiology and Behavior Ithaca, NY, USA
The olfactory bulb (OB) is modulated by a number of extrinsic
and intrinsic modulatory substances. We here synthesize work
from our lab investigating the effects of cholinergic (ACh),
noradrenergic (NE), serotonergic (5HT), dopaminergic (DA) and
hormonal modulation on olfactory perception. We compare the
behavioral effects by using well–established behavioral paradigms
such as olfactory habituation memory and reward-association.
We find that ACh modulation affects the discrimination of
chemically and perceptually similar odorants (Mandairon et al.
2006; Chaudhury et al. 2009), with specific roles for muscarinic
and nicotinic receptors (Devore et al., in prep). NE, while also
modulating odor discrimination of chemically and perceptually
similar odorants (Mandairon et al. 2006; see also Doucette et
al. 2007), also plays a specific role in regulating signal to noise
ratio when very low concentration odorants are used (Escanilla
et al 2010). In a direct comparison, NE, but not ACh, is shown
to be functionally important during learning of very low
concentration odorants (Escanilla et al 2012). DA, intrinsic to
the bulb, modulated odor concentration perception via activation
of D2 but not D1 receptors (Escanilla et al. 2009). Blockade of
5HT receptors impaired habituation memory formation and
specificity, as well as reward-driven discrimination at low, but
not higher odor concentrations (Lewis and Linster, in prep).
Both hormonal (estrodial, in mice) and NE manipulations (in
rats) extended the duration of an olfactory habituation memory
(Dillon et al, in prep; Manella et al. in prep). In summary, the
behavioral effects of OB neuromodulators, while similar at first
ORAL ABSTRACTS
Abstracts are printed as submitted by the author(s).
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