Page 63 - ACHEMS 2012 PROGRAM

#P107 POSTER SESSION III:
OLFACTION DEVELOPMENT & CNS;
HUMAN PSYCHOPHYSICS; TASTE PERIPHERY
A novel array design that incorporates tetrode recordings
with optogenetic stimulation
Quang N Dang1,2, Jamie Costabile2,3, Elizabeth Stubblefield2,3,
Saif Al-juboori4, Thomas Bozza5,6, Tim Lei4, Gidon Felsen2,3,
Diego Restrepo 1,2, David Gire1,2
1Department of Cell and Developmental Biology, School of
Medicine University of Colorado Aurora, CO, USA, 2Rocky
Mountain Taste and Smell Center and Neuroscience Program,
School of Medicine University of Colorado Aurora, CO, USA,
3Department of Physiology and Biophysics, School of Medicine
University of Colorado Aurora, CO, USA, 4Department of
Electrical Engineering, University of Colorado Denver Denver,
CO, USA, 5Janelia Farm Research Campus, Howard Hughes
Medical Institute Ashburn, VA, USA, 6Department of Neurobiology,
Northwestern University Evanston, IL, USA
With recent growth in the field of optogenetics arises the constant
need for improvements in multi-electrode array designs that
combine electrophysiological recording and optogenetic
stimulation. We present a design that allows tetrodes to be
precisely targeted to regions of the brain that are stimulated by an
LED-coupled optical fiber. This design focuses on simplicity and
precision in stimulation and surgical implantation. Our design
employs a tapered glass pipette that provides containment for the
LED-coupled optical fiber as well as guide tubes for tetrodes.
This design is ideal for use in freely moving mice, as the array is
small and light enough to be easily tolerated during behavioral
experiments. We provide technical specifications for this array
design, including the extent of light spread from the glass cannula.
We also provide data demonstrating the use of this array in the
mouse olfactory bulb to stimulate olfactory sensory neuron
terminals expressing humanized Channelrhodopsin-2 (hChR2), and
to record from mitral and tufted cells receiving this sensory input.
Acknowledgements: NIDCD R01DC009640 (TB), R21DC010911
(TB), the Whitehall Foundation and the Brain Research Foundation
(TB), State of Colorado Bioscience Discovery Evaluation Grant
(TL), Colorado Clinical Translational Science Institute (TL), the
Boettcher Foundation’s Webb-Waring Biomedical Research
Program (GF), NIDCD R01DC00566 (DR), P30DC04657 (DR),
F32DC011980 (DG)
#P108 POSTER SESSION III:
OLFACTION DEVELOPMENT & CNS;
HUMAN PSYCHOPHYSICS; TASTE PERIPHERY
Odor representations selectively imaged from inhibitory
interneurons and output neurons of the mouse olfactory bulb
Matt Wachowiak, Markus Rothermel, Marta Diaz-Qeusada,
Daniela Brunert, Mike Economo
University of Utah Department of Physiology and Brain Institute
Salt Lake City, UT, USA
To understand how olfactory information is represented and
processed across the olfactory bulb (OB) we are using the
genetically-encoded calcium sensor GCaMP3 to image activity
among genetically- and anatomically-specified populations of
OB neurons, including GABA-ergic periglomerular (PG)
interneurons and mitral and tufted (MT) cells projecting to piriform
cortex. GCaMP3 expression in these neurons was achieved using
Cre recombinase-dependent viral vector injection in mice
expressing Cre in either GAD65-positive neurons (GAD2-cre) or
protocadherin21-positive neurons (pcdh21-cre). We recorded
optical signals using epifluorescence imaging across the dorsal OB
and two-photon imaging yielding cellular-level resolution of
activity within glomeruli and as deep as the mitral cell layer.
Evoked GCaMP3 signals were large and showed clear coupling to
inhalation. Odorant response maps imaged from both MT and PG
cells appeared similar to those imaged from sensory neuron inputs,
showing a rough chemotopy organized into functional domains,
discrete foci reflecting glomerular boundaries and a strong
concentration-dependence. This result suggests that the topography
of odor representations is not drastically remodeled by OB
processing. A second major observation was a strong dependence
of MT and PG cell signals on anesthesia: odorant-evoked PG cell
responses increased as depth of anesthesia decreased, while those
of MT cells decreased and became nearly undetectable in the awake
mouse. The transition from strong to weak MT responses could
occur over a time-course of seconds. These results are consistent
with a critical role for PG cell inhibition in shaping OB output and
with the idea that both local and output neuron populations may be
strongly modulated during behavior. Acknowledgements: NIDCD
#P109 POSTER SESSION III:
OLFACTION DEVELOPMENT & CNS;
HUMAN PSYCHOPHYSICS; TASTE PERIPHERY
Modulation of the spatial representation of odors by an
olfactory associative learning in the mouse olfactory bulb
Romain Chery, Frédéric Pain, Hirac Gurden, Claire Martin
Imagerie et Modélisation en Neurobiologie et Cancérologie
(IMNC), UMR 8165, Universités Paris 7 et 11 Orsay,
F-91405, France
Plasticity of primary sensory cortices is essential for learning and
memory. In the olfactory bulb (OB), a central structure supporting
the first step of odor coding, odor stimulation evokes spatio-
temporal patterns of activity. While the temporal aspect emerges
from the functional loop between mitral cell and granular
interneurons, the spatial component is formed by the activation of
groups of glomeruli, anatomo-functional units of the OB, where
olfactory neuroreceptors make synapses with the mitral cells. In
vivo intrinsic optical signal imaging is a technique based on
changes of endogenous optical properties of the brain tissue during
activation and is commonly used to map odor-induced spatial
activity in the dorsal OB. While modulations of the temporal
component of the olfactory information have been studied through
electrophysiological recordings, changes in spatial maps following
learning in adults were not fully explored. The aim of this study is
to visualize, using intrinsic optical imaging, changes in these odor
maps following learning. Mice were implanted with a chronic
cranial window centered on the OB and activity was recorded
under anesthesia for a set of odors which will be used for training,
plus a control/neutral odor. After few days of recovery, mice were
trained to solve an odor discrimination task (go-nogo task) where
one odor is associated with reinforcement and one odor is not
associated with a reward (paired condition). In another group the
odors were randomly associated with the reinforcement (unpaired
condition). After mice had reached the criterion, maps for these
three odors were recorded in the same conditions as initially, in
order to compare the response profile before and after learning.
We observed no reorganization of spatial maps or change in the
intensity of odor responses in the paired group. However in the
unpaired group, while the spatial maps were not modulated by the
odor stimulation, we saw a decrease of responses following
presentation of odors uses during training. No change was observed
for the control odor. Taken together, our data indicate an impact of
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