|
Neuroscience
Cluster Scientific Retreat |
|
Graduate Student, Committee on Neurobiology Does the sampling of an
odor stimulus modulate the way it is perceived? On entering the nose,
a stream of air carrying an odorant will elicit a particular pattern of
spatial excitation along the olfactory epithelium, depending mainly on its
ability to dissolve (what is called the /sorptiveness/
of the odorant) in the mucus covering the epithelium. Several lines of
evidence suggest that these odorant-specific activation patterns depend also
on the flow of the airstream, implying that the activation of different
subsets of olfactory sensory neurons is a function of the odorant sampling
process, i.e., the animalā€™s sniffing.
This has been called the 'Chromatographic hypothesis', due to the analogies
between the nasal passageways and a chromatographic column. The evidence
comes mainly from anesthetized or /ex vivo/ preparations, and had not been
tested in behaving animals facing olfactory discriminations. My project aims to
study sniffing patterns in the rat during olfactory discriminations. These
discriminations involve odorants that differ in sorptiveness,
in such a way that the animal is required to disambiguate mixtures of
different chemicals. If the animal takes advantage of the abovementioned
chromatographic properties when discriminating stimuli, then it is expected
that different sniffing strategies are required to perform discriminations of
odorants differing in sorptiveness. To look at sniffing,
I record the electromyographic activity of the
diaphragm of the albino rat, in chronically implanted animals. This signal
gives me information about duration of respiratory events (i.e., inspiration,
expiration), as well as an indirect estimation of the volume of air inhaled
in each sniff. I also record local field potentials from two brain areas that
are crucial for olfaction: olfactory bulb and pyriform
cortex. Animals are trained to perform an olfactory discrimination task, and
recordings are being made during the performance of this task. 09/03/2009 |