Abstracts - Association for Chemoreception Sciences

P O S T E R S
#P213 POSTER SESSION V:
CENTRAL OLFACTION; CHEMOSENSORY
PSYCHOPHYSICS & CLINICAL STUDIES
An Ih-dependent Switch from Inhibition to Excitation in ET
Cells by Co-release of GABA and DA from SA Cells
Zuoyi Shao, Shaolin Liu, Adam C. Puche, Michael T. Shipley
Department of Anatomy & Neurobiology, Program in
Neuroscience, University of Maryland School of Medicine
Baltimore, MD, USA
Olfactory bulb short axon (SA) cells co-express DA and GABA
and form multiglomerular circuits spanning 10’s-100s of
glomeruli. ET cells receive direct ON input and provide
excitatory drive to SA, PG and mitral/tufted (MT) cells. Thus
modulation of ET cells significantly impacts glomerular
processing and OB output to olfactory cortex. There is evidence
that ET cells receive synaptic input from the GABA-DAergic SA
cells. How does co-release of DA and GABA influence ET cells?
ET cells respond to stimulation of SA cell interglomerular circuit
with short latency hyperpolarization followed by a strong
rebound depolarization that generates a burst of action potentials.
Both the initial hyperpolarization and the rebound spike burst
were blocked by gabazine. Brief hyperpolarization of ET cells
leads to strong rebound depolarization due to activation of a
prominent Ih current. Thus, ET cell hyperpolarization mediated
by SA cell GABA release might activate Ih triggering the rebound
spike burst. In many CNS neurons DA enhances Ih. Indeed, bath
applied DA (in the presence of fast synaptic blockers) increased Ih
in ET cells. Thus co-release of DA by SA cells might strengthen
the GABA-induced rebound excitation. Consistent with this
hypothesis, upon SA stimulation the rebound depolarization, but
not the initial hyperpolarization, was significantly attenuated by
D1-like antagonists. ET cells drive PG cells, which inhibit MT
cells. Thus the net result of SA cell activation may be to generate
interglomerular inhibition of MT cells. Further, the present
findings demonstrate a novel neural mechanism whereby synaptic
inhibition is transformed into strong excitation by target cell
intrinsic properties and DA modulation. Acknowledgements:
Supported by NIH NIDCD DC005676
#P214 POSTER SESSION V:
CENTRAL OLFACTION; CHEMOSENSORY
PSYCHOPHYSICS & CLINICAL STUDIES
Olfactory-visual integration facilitates perceptual
discrimination of facial expressions
Emily Cahill, Lucas Novak, Wen Li
University of Wisconsin-Madison Madison, WI, USA
Multisensory integration markedly improves perception of a
stimulus, especially when the sensory input is minimal (known as
“the rule of inverse effectiveness”). Research has largely focused
on cross-modal interactions among senses other than olfaction,
implicating the thalamus as a primary neural substrate in this
process. Given that olfactory input bypasses this structure en
route to the primary olfactory cortex, this theory is unlikely to
figure well in olfaction-related sensory merging. It thus remains to
be explored how olfactory information interacts with other
sensory stimulation. In this study, we examined the effect of odor
on the discrimination of two highly similar faces using a dotprobe
paradigm in combination with brain event-related
potentials. On a given trial, we delivered an unpleasant or neutral
odor for 2 sec, and then presented a pair of faces simultaneously
in the left and right visual fields for 400ms, followed by a dot
appearing at the location of either of the faces. In each pair, one
face contained a neutral expression and the other face the neutral
expression morphed with 12.5% of fearful expression of the same
person. Despite that a two-alternative-forced-choice task
confirmed that these faces were indistinguishable, a visual ERP
component, P1, appearing at 90 ms post-stimulus indicated visual
discrimination of the faces in the presence of unpleasant (vs.
neutral) odors, varying as a function of the level of anxiety of the
subjects (P