Expertise:
Behavioral
electrophysiology, olfactory psychophysics, time series analysis,
computation
Olfactory perception is unique among sensory systems, as
there are sensory afferents that project directly into cortex
(the olfactory bulb). This same structure receives central
input from most of the limbic system (including the hippocampus,
entorhinal cortex and amygdala), as well as olfactory cortex
(pyriform cortex) and many brainstem modulatory regions (e.g.,
locus coeruleus, raphe nuclei, diagonal band of Broca). We
use this unique architecture to study direct influences of
learning, attention and experience on primary sensory activity.
We use the local field potential and prominent olfactory
system gamma band oscillations as markers for underlying
neural synchrony, and many of our studies address modulation
of this synchrony by behavioral state and with learning (Kay
and Freeman, 1998; Kay, 2003) . Single unit recordings in
the olfactory bulb and hippocampus also address the role
of experience on odor coding and higher order associations
(Kay and Laurent, 1999) . We also use pharmacological manipulation
to change the level of synchrony in the olfactory bulb, which
results in reliable deficits and improvements in odor discrimination.
We combine many of these studies with recordings in the respiratory
system to examine the role that motor attention (sniffing)
plays in modulating sensory processing (Kay, 2005) . In order
to describe these processes it is necessary to understand
the importance of anatomical ordering of sensory input. We
therefore also use psychophysics to uncover the rules governing
odorant mixture perception which may be determined by hard
wiring (Kay et al., 2003; Kay et al., 2005) .
All of our studies use rats and mice, and all electrophysiology
is done with chronically implanted electrode arrays in multiple
areas of the olfactory and limbic systems. Single unit recordings
use multiple individually moveable electrodes (single etched
metal electrodes and tetrodes). In some experiments we also
record EMG activity as a measure of respiratory drive. Recordings
are made using 32-channel Neuralynx Cheetah systems during
operant odor discrimination tasks with simultaneous control
of behavioral equipment (MedAssociates and Coulbourn).
Thus far, our studies have shown that anatomical structure
can predict some features of odor mixture perception, and
physical properties of some odorants produce distinct oscillatory
patterns in the olfactory system, which mimic those found
after learning. Aside from these studies of the intrinsic
properties of odorants and the olfactory system, we find
that even the first relay in olfactory processing (mitral
cells in the olfactory bulb) is strongly affected by an animal’s
behavior, prior experience with an odor and learned associations.
Synchrony in the olfactory bulb, whether manipulated behaviorally,
pharmacologically or genetically produces reliable changes
in odor discrimination ability, with increases in synchrony
accompanying improved odor discrimination and decreases accompanying
deficits in odor discrimination. Finally, locking at the
sniffing frequency between the olfactory bulb and hippocampus
accompanies improvements in odor discrimination in a difficult
sensorimotor task, suggesting that respiratory attention
is key to modulating sensory information.
Specific research projects:
-- Multiple gamma oscillations in the rat olfactory system – Behavioral
physiology and computational modeling; collaborative project
with Nancy Kopell at Boston University
-- Olfactory, hippocampal and respiratory interactions
in olfactory perception – Behavioral physiology
-- Modulation of olfactory perception by experience – Collaborative
with Christiane Linster, Cornell University
-- Rules regarding odor mixture perception – Psychophysics
of binary mixtures
Laboratory personnel:
Claire Martin, PhD, Postdoctoral Fellow
clmartin@uchicago.edu
Catherine Lowry, Graduate student in Neurobiology
calowry@midway.uchicago.edu
Jennifer Beshel, Graduate student in Psychology
beshel@uchicago.edu
Emma Wyatt, Graduate student in Psychology
ewyatt@uchicago.edu
Daniel Rojas, Graduate student in Neurobiology
dirl@uchicago.edu
Magdalena Krysiak, Undergraduate in Biology/Psychology
mag@uchicago.edu
Lale Barlas, Undergraduate in Psychology
lale@uchicago.edu
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