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Incorporating periodic variability in hidden Markov models for animal movement

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The Gene Ontology and the Meaning of Biological Function

More harm than good? The questionable ethics of medical volunteering and international student placements

Soup and Reform: Improving the Poor and Reforming Immigrants through Soup Kitchens 1870–1910

Ivy Shiue

Caregivers had neighbourhood support but perceived it unsatisfactory and worsened: England Community Life Survey, 2012–2014

ML Oshinsky

AL Murphy

ME Cooper

BJ Simon

POSTER PRESENTATION Open Access
Trigeminal pain is suppressed by non-invasive
vagal nerve stimulation in a rat headache model
ML Oshinsky1*, AL Murphy2, ME Cooper2, BJ Simon3
From The European Headache and Migraine Trust International Congress
London, UK. 20-23 September 2012
Introduction
Non-invasive vagal nerve stimulation (nVNS) is a novel
technology for painless stimulation of the vagus nerve
through the skin on the neck. Using a rat model of trigem-
inal allodynia, we tested the ability of nVNS to suppress
the behavioral response and neurotransmitter changes fol-
lowing trigeminal pain. In this model, nociceptor activa-
tion is induced by infusing an inflammatory soup onto the
dura in awake rats. This is repeated 3 times per week for
4 weeks. This stimulation leads to a state of secondary
chronic pain on the face, which matches the pattern of
referred pain in the migraineur.
Objective
To study the mechanism of action of nVNS on beha-
vioral and physiological correlates of trigeminal pain.
Methods
One week after the last infusion, electrodes were posi-
tioned on the neck over the vagus nerve and the animal
was stimulated for 1min. The nVNS signal consisted of
1ms bursts of a 5kHz sine wave repeated at 25Hz. The
peak voltage applied was 22V. The control for nVNS was
electrode placement, without stimulation. Another group
of rats were used for microdialysis studies to determine
the mechanism of action of nVNS effect on trigeminal
pain. Rats were anesthetized and placed in a stereotaxic
frame. Using a small microdialysis probe, extracellular
amino acids were sampled for up to 3.5hr after GTN
(0.1mg/kg) treatment with and without nVNS stimulation.
Results
Following the 10 infusions of the IS, the rats were allody-
nic. All of the rats responded to nVNS stimulation with
an increase in their periorbital pain threshold within
5min. This effect was maintained for at least 3.5hr after
the stimulator was turned off. GTN treatment elicited a
>7 fold increase in extracellular glutamate, which peaked
at ~2hr after treatment. This increase in glutamate was
completely blocked by 2min of nVNS stimulation.
Conclusion
In a rat model of recurrent headache, both behavioral
and physiological measures of trigeminal pain and allo-
dynia are suppressed by 1-2min of nVNS. Funding: NIH
R01-NS061571, ElectroCore LLC. COI: Bruce Simon is
an employee of ElectroCore LLC.
Author details
1Thomas Jefferson University, USA. 2Thomas Jefferson Unversity, USA.
3ElectroCore LLC., USA.
Published: 21 February 2013
Reference
1. Oshinsky ML, Gomonchareonsiri S: Episodic Dural Stimulation in Awake
Rats: A Model for Recurrent Headache. Headache 2007, 47:1026-1036,
Oshinsky ML, Luo J. Neurochemistry of Trigeminal Activation in an Animal
Model of Migraine. Headache.2006;46: S39-S44.
doi:10.1186/1129-2377-14-S1-P80
Cite this article as: Oshinsky et al.: Trigeminal pain is suppressed by
non-invasive vagal nerve stimulation in a rat headache model. The
Journal of Headache and Pain 2013 14(Suppl 1):P80.
1Thomas Jefferson University, USA
Full list of author information is available at the end of the article
Oshinsky et al. The Journal of Headache and Pain 2013, 14(Suppl 1):P80
http://www.thejournalofheadacheandpain.com/content/14/S1/P80
© 2013 Oshinsky et al; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.


Trigeminal pain is suppressed by non-invasive vagal nerve stimulation in a rat headache model

GJ Metzger

S Schmitter

X Li

P Van de Moortele

P Schmitt

X Bi

WORKSHOP PRESENTATION Open Access
Four-dimensional noncontrast-enhanced MR
angiography at ultrahigh field
GJ Metzger1*, S Schmitter1, X Li1, P Van de Moortele1, P Schmitt2, X Bi3
From 16th Annual SCMR Scientific Sessions
San Francisco, CA, USA. 31 January - 3 February 2013
Background
Arterial spin labeled (ASL) 4D MRA has been shown to
be a valuable method for simultaneously assessing ana-
tomic structure and dynamic filling of cerebral arteries.
Beyond improved SNR and parallel imaging perfor-
mance, performing these studies at ultrahigh field will
benefit from longer T1s resulting in more persistent
labeling allowing for improved visualization of distal ves-
sels, especially in conditions of reduced flow.
Methods
Studies were performed on Siemens 7T whole body MRI
scanner with a 16-channel transceiver TEM stripline
array head coil driven by a series of 16, 1 kW amplifiers
(CPC, Pittsburgh, PA). Non-contrast enhanced 4D ASL
MRA was performed using an ECG-triggered, segmented,
3D acquisition using signal targeting with alternating
radiofrequency (STAR) for spin labeling. Label and con-
trol volumes were acquired with magnetization prepara-
tion immediately after the ECG R-wave and before the
segmented readout used to generate the time resolved
frames (Fig. 1). Background saturation over the imaging
volume was applied for both label and control volumes.
Data was acquired with 26 frames over 1700 ms (two R-R
intervals) with a temporal resolution of ~60 ms and an
acquisition time of 12:23.
To address the challenges of B1+ homogeneity and effi-
ciency at 7T, B1+ shimming was performed based on a
small flip angle, calibration scan. Two B1+ shimming
strategies were compared; 1) a static approach which
used a CP-like mode over the entire brain for all RF
pulses in the sequence, and 2) a dynamic approach which
used a separate B1+ shim optimized for efficiency for the
IR labeling pulse (Shim 1) and the CP-like mode for exci-
tation and background suppression (Shim 2) (Fig. 1).
Results
The CP-like mode provides reasonable transmit effi-
ciency and homogeneity over the head and is a sensible
solution for RF pulses applied within the imaging volume.
At the location of the labeling volume however, B1+ is
appreciably weaker and thus benefits from its own shim
focusing on optimized efficiency. By using an efficient
solution optimized specifically on the labeling volume for
the IR pulse and the CP-like mode for excitation and
background suppression, far superior images were
obtained. Higher labeling efficiency in the dynamically
applied B1+ shimming strategy resulted in higher con-
trast between the vessels and surrounding tissue. With
this acquisition strategy and the increased T1s of blood
at 7T, dynamics of distal cerebral vessels were nicely
characterized out to 1.56 s post labeling (Fig. 2).
Conclusions
A dynamically applied transmit B1 (B1+) shimming strat-
egy was employed to accommodate limitations on peak
B1+, B1+ homogeneity and SAR for four-dimensional
non-contrast enhanced angiography at 7T. Initial results
showing signal persistence in distal arteries is made pos-
sible by the increased labeling efficiency of the dynamic
B1+ shimming approach as well as the increased T1s of
blood at ultrahigh field.
Funding
Funding Provided by P41 EB015894, S10 RR26783 and
WM KECK Foundation.
1Center for Magnetic Resonance Research, University of Minnesota,
Minneapolis, MN, USA
Full list of author information is available at the end of the article
Metzger et al. Journal of Cardiovascular Magnetic
Resonance 2013, 15(Suppl 1):W11
http://www.jcmr-online.com/content/15/S1/W11
© 2013 Metzger et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Author details
1Center for Magnetic Resonance Research, University of Minnesota,
Minneapolis, MN, USA. 2MR Application & Workflow Development, Siemens
AG, Erlangen, Germany. 3Cardiovascular MR R&D, Siemens Healthcare,
Chicago, IL, USA.
Published: 30 January 2013
doi:10.1186/1532-429X-15-S1-W11
Cite this article as: Metzger et al.: Four-dimensional noncontrast-
enhanced MR angiography at ultrahigh field. Journal of Cardiovascular
Magnetic Resonance 2013 15(Suppl 1):W11.
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Figure 1 Volumetric MIPs at every 4th frame up to 1.02 s post labeling (upper row). Normalized signal intensity over 2 RR intervals at 5 locations
over all 28 frames encompassing 1.68 seconds after labeling (lower row). The zoomed region on which the ROIs are placed is demarcated in the
last frame of the upper row.
Figure 2 4D ASL MRA sequence. The label volume is acquired with an inversion labeling (IR) pulse on and the control volume with the IR pulse
off. Background suppression (BS) is applied in the imaging volume for label and control volume acquisitions. The locations for the dynamically
applied B1+ shim solutions are shown by the labels “Shim 1” and “Shim 2”.
Metzger et al. Journal of Cardiovascular Magnetic
Resonance 2013, 15(Suppl 1):W11
http://www.jcmr-online.com/content/15/S1/W11
Page 2 of 2


Four-dimensional noncontrast-enhanced MR angiography at ultrahigh field

Ruben J. van der Wekken

Hans Kemperman

Mark Roest

Dylan W. de Lange

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Armin Hofmeister

Johannes Böhm

Application of ray-traced tropospheric slant delays to geodetic VLBI analysis

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