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#P69 WITHDRAWN
#P70
POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Negative Olfactory Alliesthesia in Anxiety:
An fMRI investigation
Elizabeth A Krusemark, Wen Li
University of Wisconsin Madison, WI, USA
Olfactory hedonic evaluation tends to depend on the perceiver’s
internal state (known as olfactory alliesthesia). Accordingly, the
internal state of anxiety can negatively shift odor valence and
confront anxious people with increased olfactory stress in everyday
life. Combining anxiety provocation and fMRI techniques, we
interrogated anxiety-state-dependent affective evaluation and
perceptual coding of initially neutral odors.We predicted that
anxiety would increase aversion to odors via altered hedonic
judgments subsequent to the experimental manipulation (negative
olfactory alliesthesia). In parallel to behavioral observation, we
predicted fMRI response amplification in olfactory and limbic
circuitry with increased anxiety. Analyses indicated that induced
anxiety led to more negative hedonic judgments for neutral odors
(pure odors and mixtures;
N
=16;
p
<.05). Consistently, anterior
piriform, hippocampus, orbitofrontal, and insular cortices showed
significant response enhancement to both pure and odor mixtures
(versus air) post anxiety induction (
N
=12;
p
<.001, uncorrected).
Therefore, our data highlighted the possibility that anxiety can
negatively bias affective evaluation of one’s olfactory environment,
causing otherwise benign odors to become intrusive. This finding
may provide a novel etiological model of anxiety where anxiety
subjects affected individuals to heightened olfactory distress,
thereby fueling and perpetuating anxiety symptoms.
Acknowledgements: Parts of this research were funded by a
Training grant from the National Institute of Health
T32-MH018931-22 to E.A.K.
#P71
POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Correlation between olfactory bulb volume and olfactory
function in children and adolescents
Thomas Hummel
1
, Martin Smitka
2
, Stefan Puschmann
1
,
Johannes Gerber
3
, Benoist Schaal
4
, Dorothee Buschhüter
1
1
Univ of Dresden Med School, Dept of ORL, Smell & Taste Clinic
Dresden, Germany,
2
Univ of Dresden Med School, Dept of
Pediatrics Dresden, Germany,
3
Univ of Dresden Med School,
Dept of Neuroradiology Dresden, Germany,
4
Centre de Gout
Dijon, France
The olfactory bulb (OB) is considered to be the most important
relay station in odor processing. The present study aimed to
investigate the volumetric development of the human bulb and the
olfactory function during childhood and youth. Furthermore the
present study aimed to investigate a possible correlation between
OB volume and specific olfactory functions including odor
threshold, odor discrimination and odor identification. A total of
87 subjects (46 male, 41 female), aged 1 to 17 years (mean age 8
years), participated in this study. None of them reported olfactory
dysfunction or had signs of a dysfunctional sense of smell.
Whenever possible, participants received a volumetric scan of the
brain (MRI) and lateralized olfactory tests. Volumetric
measurements of the right and left OB were performed by manual
segmentation of the coronal slices through the OB. Significant
correlations between OB volumes and olfactory function was
observed. Both, OB volumes and olfactory function increased with
age, although the correlation between structure and function was
not mediated by the subjects’ age. In conclusion, for the first time
the present study showed a correlation between OB volume and
olfactory functions in children. Acknowledgements: Supported by
the DDELTAS (Dijon-Dresden European Laboratories for Taste
and Smell - LEA 549), underwritten by the Centre National de la
Recherche Scientifique-Paris and the Technische Universität
Dresden, and awarded to BS and TH, and a grant from the Roland
Ernst Stiftung to TH.
#P72
POSTER SESSION II:
TRIGEMINAL SYSTEM; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Cholinergic modulation of olfactory bulb mitral/tufted cell
glomerular odor responses
Max L. Fletcher
University of Tennessee Health Science Center Memphis, TN, USA
Olfactory receptor neurons project their axons to specific glomeruli
across the olfactory bulb. This convergence of ORN input into the
OB forms the basis of odorant-specific spatial maps of mitral/tufted
(M/T) cell glomerular activity. This initial stage of olfactory
information processing receives heavy cholinergic fiber input from
the horizontal limb of the diagonal band (HDB). In other sensory
systems, basal forebrain cholinergic input has been shown to
enhance responses to salient or novel stimuli by increasing signal-
to-noise ratios and altering neuronal receptive fields. While much
work has focused on the role of cholinergic modulation of sensory
responses to input in primary cortical areas, comparatively little is
known about its impact on earlier sensory regions. To explore this
question, we visualized OB glomerular odor responses to ORN
input in transgenic mice expressing a calcium-sensitive fluorescent
indicator of neuronal activity (GCaMP2) in all M/T cells while
manipulating cholinergic release into the olfactory system. We
found that electrical stimulation of the HDB causes a large and
immediate increase in M/T cell population glomerular odor
responses that lasts the length of the odor response. Through
combined HDB stimulation and pharmacological manipulation,
we also found that cholinergic enhancement of M/T cell population
glomerular odor responses is primarily driven by muscarinic
receptor activation within the OB. Current experiments are
underway investigating the functional consequences of this
cholinergic enhancement of glomerular odor responses in terms
OB odor coding and plasticity. Overall, these studies will enhance
our understanding of how neuromodulation shapes neuronal
processing of sensory stimuli at the earliest stages of sensory input
into the central nervous system. Acknowledgements:
Acknowledgements: R03 DC009853 and the Pew Scholars
Program in the Biomedical Sciences
Abstracts | 51
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