Givaudan-Roure Lecture - Association for Chemoreception Sciences

219 Poster [ ] Olfactory Bulb: Coding
THE EFFECTS OF STIMULUS DYNAMICS ON OLFACTORY
LOBE RESPONSES IN THE CRAYFISH, PROCAMBARUS
CLARKII USING ENSEMBLE RECORDING TECHNIQUES
Wolf M. 1, Daly K. 2, Moore P.A. 1 1Biological Sciences, Bowling Green
State University, Bowling Green, OH; 2Entomology, Ohio State
University, Columbus, OH
Two major issues facing sensory ecologists are how olfactory
information is coded in the nervous system and that information
correlates with behavior. Behavioral results from our lab indicate that
crayfish are sensitive and respond to temporal components of an odor
signal. As such, we expect to find that underlying this sensitivity to
stimulus dynamics, are neural correlates evident within the olfactory
system. Thus, in this preliminary study, we investigated how the
temporal aspects of an odor signal are coded in the olfactory lobe of the
crayfish. Neural ensemble recordings were made on an isolated head
preparation perfused with oxygenated crayfish saline. Silicon
multichannel electrode arrays were inserted into the olfactory lobe of
the crayfish brain. The medial antennule was placed into an
olfactometer and stimulated with 3 types of stimuli; glutamate, glycine,
and shrimp extract. The stimuli were presented at a specific molar
concentration (10-5 M) and duration (500 ms), varying only the
intermittency between odor pulses. Our results suggest that coordinated
clusters of units, which collectively produced odor-dependent responses
but these responses were further dependent on stimulus intermittency.
These results are consistent with our behavioral data demonstrating that
crayfish are sensitive to the manner in which odors are experienced.
This work was supported by the McDonnell Foundation (KCD),
NIDCD-DC05535, KCD and a Sigma Xi Grant-in-aid of research
(MCW)
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220 Poster [ ] Olfactory Bulb: Coding
THE EFFECT OF STIMULUS DURATION ON EUCLIDIAN
RESPONSE DISTANCE MEASURES OF ODOR
DISCRIMINATION ACROSS ANTENNAL LOBE
POPULATIONS IN MANDUCA SEXTA.
Daly K.C. 1, Smith B.H. 1 1Entomology, Ohio State University,
Columbus, OH
Behavioral studies suggest that animals such as the moth Manduca
sexta perceive subtle differences between odorant based on changes
molecular features such a carbon chain length. Recent theories of
temporal coding predict that closely related odors are “decomposed”
over time and that longer duration stimulations should provide
additional information used by the antennal lobe (AL) or olfactory bulb
to enhance discrimination. To test this we measured the degree to which
AL ensembles could statistically discriminate closely related odors as a
function of increasing stimulus duration. Multiunit recordings from
moths ALs were analyzed in response to 6 alcohols and ketones that
were repeatedly presented at odor pulse durations ranging from 50 to
4000 ms. Principle Components Analysis, on binned data (10ms),
extracted orthogonal factors each representing a collection of units with
common and coordinated responses. General Linear Modeling
identified factors with odor-dependent temporal effects (p< 0.001).
Odor-dependent factors were treated as independent dimensions and the
Euclidian distance between odor responses at bin was calculated in a
high dimensional space. We find that population trajectories rapidly
peak (animal specific ~120-240 ms) and does so at the same time
irrespective of stimulus duration. For longer durations, trajectories do
tend to stay separated for the duration of the pulse length. These
preliminary results suggest that olfactory systems have the capacity to
represent odorant identity of subtly different odors rapidly. Supported
by NIH-NCRR; RR14166-06 (BS) & NIH-NIDCD; DC05535-01 and
the McDonnell Foundation (KD)
221 Poster [ ] Olfactory Bulb: Coding
CHARACTERIZATION OF LABELED CELLS IN THE
OLFACTORY BULB OF TRANSGENIC ZEBRAFISH
EXPRESSING THE SIMIAN CYTOMEGALOVIRUS (SCMV)
PROMOTER
Fuller C.L. 1, Suhr S.T. 2, Goldman D.J. 2, Byrd C.A. 1 1Biological
Sciences, Western Michigan University, Kalamazoo, MI; 2Mental
Health Research Institute, University of Michigan, Ann Arbor, MI
The CMV promoter is commonly used for the production of
transgenic animals due to its effective and essentially ubiquitous
expression. We used a simian CMV promoter to drive the expression of
a fluorescent reporter protein, dsRed, in zebrafish. Expression of the
sCMV promoter has been confirmed in several regions throughout the
nervous system including a specific subset of cells in the olfactory bulb.
These olfactory bulb cells were among the first to express the transgene
early in development. The purpose of this study was to examine the
morphology, distribution, and identity of the labeled cells in the
olfactory bulb using confocal microscopy, immunocytochemistry, and
retrograde tract-tracing methods. The labeled cells have teardropshaped
somata that are 5-10 microns in diameter. The cell bodies are
found throughout the glomerular and superficial internal cell layers, and
they possess a single prominent process containing tufts in the
glomerular layer. Although these cells are found in the same location as
mitral cells, they do not appear to be output neurons since retrograde
labeling of the olfactory tracts with a fluorescent dextran identifies a
different subset of bulbar cells. We are continuing our exploration of
the identity of the bulbar neurons that are labeled in these transgenic
zebrafish.
Supported by NIH DC04262 (CAB) and a grant from the Hereditary
Disease Foundation: Cure Huntington´s Disease Initiative (STS).