Abstracts - Association for Chemoreception Sciences

#29 SYMPOSIUM - SENSORY
INTEGRATION AND COMPETITION
Smelling sounds: olfactory–auditory sensory convergence in
the olfactory tubercle
Daniel W. Wesson 1,2 , Donald A. Wilson 1,2
1
Nathan Kline Institute for Psychiatric Research Orangeburg, NY,
USA, 2 New York University School of Medicine New York, NY,
USA
The olfactory code is influenced by numerous factors, including
behavioral state, odor-sampling patterns and cross-modal sensory
convergence. Growing evidence supports the view that primary
olfactory cortical regions are not unimodal, but instead represent
information from several sensory modalities – providing a
substrate for sensory convergence early in olfactory processing.
Adding to previous reports of both gustatory and visual
influences on the cortical processing of odors, here we report
novel findings revealing that the olfactory code is subject to
auditory cross-modal influences. In vivo extracellular recordings
from the olfactory tubercle, a tri-laminar structure within the
basal forebrain, of anesthetized mice revealed that olfactory
tubercle single-units selectively respond to odors – with 65% of
units showing significant odor–evoked activity. Remarkably, 19%
of olfactory tubercle single-units also showed robust responses to
an auditory tone. Furthermore, 29% of single-units tested
displayed supra-additive or suppressive responses to the
simultaneous presentation of odor and tone, suggesting crossmodal
modulation. In contrast, olfactory bulb units did not show
significant responses to tone presentation, nor modulation of
odor-evoked activity by tone – suggesting a lack of olfactoryauditory
convergence upstream from the olfactory tubercle. Thus,
the tubercle presents itself as a source for direct multimodal
convergence within an early stage of odor processing, and may
serve as a seat for psychophysical interactions between smells and
sounds. Acknowledgements: NIDCD grant DC003906 to D.A.W.
#30 SYMPOSIUM - SENSORY
INTEGRATION AND COMPETITION
Multisensory stimulation modulates perceptual ratings and
neuronal activity
Jessica Albrecht 1 , Jay A. Gottfried 2,3 , Johan N. Lundstrom 1,4,5
1
Monell Chemical Senses Center Philadelphia, PA, USA,
2
Department of Neurology, Northwestern University Feinberg
School of Medicine Chicago, IL, USA, 3 Department of Psychology,
Northwestern University Weinberg College of Arts and Sciences
Chicago, IL, USA, 4 Department of Psychology, University of
Pennsylvania Philadelphia, PA, USA, 5 Department of Clinical
Neuroscience, Karolinska Institute Stockholm, Sweden
Over the last few decades, sensory perception and its
neurobiological substrates have been extensively studied.
However, up until recently, most of this research has focused on
only one modality in isolation, thus standing in sharp contrast to
how we experience multimodal stimuli in our everyday lives.
Multimodal sensory experiences, such as seeing, hearing, and
smelling a coffee brewer or a popcorn machine, have the
behavioral advantage of being more easily identifiable than
unimodal stimuli alone. The aim of this series of studies was to
investigate the perceptual and neural correlates of multisensory
integration using behavioral testing and event-related functional
MRI. We used odors, short videos, and sounds originating from
six distinct stimulus objects, evenly split between positive and
negative percepts. Congruent as well as incongruent stimulus
combinations were administered to allow for comparison of the
unimodal sensation with the multimodal combination of the
stimuli. The behavioral results show that perceptual ratings of
multisensory stimuli differed compared to their bimodal
equivalent. Moreover, increased cerebral activation in response to
multisensory integration occurred bilaterally in areas known to
integrate crossmodal stimuli and bilaterally in a not previously
demonstrated integration area residing within the superior frontal
gyrus. The benefits of multisensory experiences for perceptual
and neuronal processing and their implication in our everyday life
will be discussed. Acknowledgements: Supported by start-up
funds from the Monell Chemical Senses Center awarded to JNL
and a DAAD postdoctoral fellowship D/08/40252 awarded to JA.
#31 SYMPOSIUM - SENSORY
INTEGRATION AND COMPETITION
fMRI and TMS studies of multisensory integration
Michael S Beauchamp
University of Texas Medical School Houston, TX, USA
In the first part of the talk, I will discuss human brain areas that
fMRI suggests are important for multisensory integration. The
first area, the intraparietal sulcus, is important for integration of
vision and touch. The second area, the superior temporal sulcus,
is important for the integration of the visual and auditory
modalities. In the second part of the talk, I will discuss how the
brain performs multisensory integration when it is presented with
conflicting information from different modalities; and, more
generally, how it handles situations in which different sensory
modalities provide information about the environment that is
more or less reliable. The concept of Bayes-optimal integration
will be introduced, and imaging experiments that explore the
neural mechanisms for optimal multisensory integration will be
described. Finally, I will discuss what happens to perception when
brain areas for performing multisensory integration are disrupted
using transcranial magnetic stimulation (TMS).
Acknowledgements: NSF and NIH
#32 SYMPOSIUM - SENSORY
INTEGRATION AND COMPETITION
Odor information processing by the olfactory bulb analyzed
in gene-targeted mice
Minmin Luo
NIBS Beijing, China
In mammals, olfactory sensory neurons (OSNs) expressing a
specific odorant receptor (OR) gene project with precise
stereotypy onto one or a few glomeruli in the main olfactory bulb
(MOB). In recent years we examined the functional connectivity
of bilateral olfactory bulbs and the representation of olfactory
signals by mitral/tufted cells, the projection neurons of the bulb.
By focal injection of tracer into genetically identified glomeruli,
we have found that the anterior olfactory nucleus pars externa
(AONpE) links isofunctional olfactory columns in the bilateral
MOB and serves an important role in bilateral exchange of
odorant-specific information. By recording from OSNs
expressing mouse I7 receptor and their postsynaptic neurons in
the bulb, we found that I7 OSNs and their corresponding M/T
cells exhibit similarly selective tuning profiles at low
concentrations. Increasing the concentration significantly reduces
16 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)