TRADITIONAL POSTER - ismrm

1195. Complexity in the Spatiotemporal Hemodynamic Response to Sensory Stimulation in the Un-
Anesthetized Rat
Christopher James Martin 1 , Jason Berwick 2 , Ying Zheng 2 , John Mayhew 2
1 Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom; 2 University of Sheffield
Poster Sessions
The aim of this work was to investigate the spatiotemporal changes in hemodynamics that underlie fMRI signal changes in response to stimulus evoked
changes in neuronal activity. We used optical imaging spectroscopy in an un-anesthetized rat model, to provide measures of changes in blood volume and
oxygenation at higher spatial and temporal resolution than possible with fMRI, without the potentially confounding effects of anesthesia. We found a
complex spatiotemporal hemodynamic response function, consisting of both increases and decreases in blood volume and oxygenation as well as oscillatory
response components. We discuss the implications of these findings for fMRI.
1196. BOLD Changes in Somatosensory Cortex of Malnourished Rats
R Martin 1 , R Godinez 1 , Alfredo O. Rodriguez 1
1 Departament of Electrical Engineering, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF, Mexico
Malnutrition is a main public health problem in developing countries. Incidence is increasing and the mortality rate is still high. Functional Magnetic
Resonance Imaging (BOLD) was used for mapping brain activity of malnourished rats. The food competition method was applied to a rat model to provoke
malnutrition during lactation. The vibrissae-barrel axis was also used due to its advantages for studying structure, function, development and plasticity
within the somatosensory cortex. BOLD response changes caused by the trigeminal nerve stimulation on brain activity of malnourished and control rats were
obtained at 7T. Results showed a major neuronal activity in malnourished rats.
1197. Temporal Hemodynamic Responses of BOLD FMRI in the Rat Brain Related to Electric Forepaw
Stimulation
Dewen Yang 1 , Zhiyong Xie 1 , James Goodman 1 , Anne Burkholder 2 , Nancy Poy 2
1 BioImaging COE, Pifizer Global Research & Development, Groton, CT, United States; 2 WW Comparative Medicine, Pifizer Global
Research & Development, Groton, CT, United States
The neurovascular response to electric forepaw stimulation (EFS) was observed with BOLD signal in the contralateral somatosensory cortex in 11 rats with
normal blood gas physiology under alpha-chloralose anesthesia. Serial CBF maps were also acquired during EFS in a subset of these rats. BOLD activation
and CBF maps showed elevated blood flow in the contralateral somatosensory cortex at the time of stimulation, after which the regional activation and
increases in CBF spread to cortex in the ipsilateral hemisphere.
1198. Reduced BOLD Response in Mice Lacking Nociceptor Specific Sodium Channels (Nav1.7) Indicates
Altered Pain Processing
Simone Claudia Bosshard 1 , Christof Baltes 1 , Markus Rudin 1,2
1 Institute for Biomedical Engineering, ETH Zürich, Zurich, Switzerland; 2 Institute of Pharmacology and Toxicology, University of
Zurich, Zurich, 8057, Switzerland
Electrical stimulation of the forepaws is a widely used stimulation paradigm in functional magnetic resonance imaging (fMRI). We used transgenic mice
lacking the voltage-gated sodium channel Nav 1.7 specifically at the nociceptors (Nav1.7R-/-) to study altered pain sensitivity. Nav1.7R-/-, WT littermates
and WT animals of our lab were examined using BOLD fMRI. The detected BOLD signal changes of the Nav1.7R-/- animals were significantly reduced as
compared to the two WT groups. This is in line with behavioral data reported for these mice. This proves our method to be a valuable tool to non-invasively
study pain processing in mice.
1199. BOLD Response and Associated Metabolic Changes in the Rat Barrel Cortex Following Sustained
Trigeminal Nerve Stimulation
Nathalie Just 1,2 , Hanne Frenkel 3 , Rolf Gruetter 3,4
1 LIFMET, CIBM, EPFL, Lausanne, Switzerland; 2 Department of Radiology, UNIL, Lausanne, Switzerland; 3 LIFMET, EPFL,
Lausanne, Switzerland; 4 Department of Radiology, UNIL and HUG, Lausanne and Geneva, Switzerland
The present study examined the BOLD fMRI response of the rat barrel cortex upon sustained trigeminal nerve stimulation. Moreover, the alterations in the
barrel cortex metabolite concentration due to prolonged functional activation were measured using 1H-MRS at 9.4T. The results demonstrate that sustained
BOLD responses can be obtained reproducibly in the rat barrel cortex following prolonged trigeminal nerve stimulation. Furthermore, preliminary functional
MRS (fMRS) results show changes in several metabolites in the barrel cortex and in particular an increase in lactate levels during barrel cortex activation.
1200. The Utility of FMRI in Measuring Brain Plasticity Following Peripheral Nerve Injury
Christopher Paul Pawela 1,2 , Bharat B. Biswal 3 , Rupeng Li 2 , Anthony G. Hudetz 4 , Hani S. Matloub 1 , James
S. Hyde 2
1 Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, United States; 2 Department of Biophysics, Medical
College of Wisconsin, Milwaukee, WI, United States; 3 Department of Radiology, University of Medicine and Dentistry of New
Jersey, Newark, NJ, United States; 4 Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
In this study brain reorganization following nerve injury and repair was followed for a twelve week period with BOLD fMRI in a rat model. Primary sensory
functional return progressed over the entire study period whereas thalamic areas did not functionally return until the twelve week time point. This study
demonstrates the utility of using BOLD fMRI as a substitute for conventional electrophysiology in studies of brain plasticity and has many applications
outside of peripheral nerve injury and repair.