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Animal fMRI Hall B Wednesday 13:30-15:30 1187. Increased Sensitivity to the BOLD-FMRI Signal Response During Electrical Forepaw Stimulation in Mice Using a Cryogenic RF Probe Christof Baltes*1, Simone Bosshard*1, Thomas Mueggler1,2, Markus Rudin1,3 1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; 2Pharmaceutical Research Neuroscience, F. Hoffmann-La Roche Ltd., Basel, Switzerland; 3Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland BOLD-fMRI in mice using electrical forepaw stimulation was performed with a cryogenic transceive RF probe and a room-temperature receive-only surface coil. The effect of the increased sensitivity of the cryogenic probe on detecting BOLD responses was analyzed. In fMRI experiments, a gain in image SNR and in temporal SNR of a factor of 3.10 and 1.77 was found, respectively. As further optimization parameter adjusting the thermal shield temperature of the cryogenic probe allows for altering baseline perfusion and accordingly BOLD responses. Cryogenic cooling reduces BOLD signal variations by a factor of 1.59 and therefore increases the statistical power of fMRI. 1188. Investigating Color Vision Using FMRI: Rodent Vs Primate Andy Paul Salzwedel1, Matt Mauck2, James Kuchenbecker3, Chris Pawela1, James Hyde1, Maureen Neitz3, Jay Neitz3 1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Department of Ophthalmology, Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States; 3Ophthalmology, University of Washington, Seattle, WA, United States In a comparative study, the visual pathways of two different animal models (rodent vs primate) were probed using high field strength (9.4T) fMRI. The primary goal of this research was to assay the color vision systems of these two species in hope of demonstrating the evolutionary homology thereof. Here we present several techniques that combine to form a unique overall method for probing this pathway; pharmacological intervention (AP4), precession fMRI compatible LED based stimuli, and intra-brain controls. 1189. Detectability of the BOLD Signal Jozien Goense1, Hellmut Merkle2, Nikos Logothetis1,3 1Department of Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tuebingen, Germany; 2Laboratory of Functional and Molecular Imaging, NINDS, NIH, Bethesda, MD, United States; 3Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom The BOLD signal is a weak signal, and hence if no BOLD signal is found in an area this does not necessarily mean there is no neural activity in that area. Signal dropout, artifacts, instability, physiological noise, RF-coil inhomogeneity etc. can all reduce the SNR locally leading to decreased detectability of the BOLD signal Here we illustrate that calculation of the spatial distribution of the detection for a given set of experimental conditions allows us to estimate the confidence by which absence of an fMRI signal can be interpreted as an absence of neural activity. 1190. BOLD FMRI of Anesthetized Baboons Hsiao-Ying Wey1,2, Jinqi Li1, M. Michelle Leland3, Lisa Jones3, C Akos Szabo4, John W. Roby1, James T. Scribner1,2, Ghzawan M. Kroma2, Peter T. Fox1, Timothy Q. Duong1,2 1Research Imaging Institute, UT Health Science Center at San Antonio, San Antonio, TX, United States; 2Radiology, UT Health Science Center at San Antonio, San Antonio, TX, United States; 3Laboratory Animal Resources, UT Health Science Center at San Antonio, San Antonio, TX, United States; 4Neurology, UT Health Science Center at San Antonio, San Antonio, TX, United States This study reports a robust anesthetized baboon model for BOLD fMRI studies on a clinical 3T human MRI scanner. BOLD fMRI of visual and somatosensory/motor stimulations in anesthetized baboons were investigated. Comparisons of BOLD fMRI sensitivity were made between isoflurane and ketamine anesthetics with and without paralytics. To our knowledge, this is the first report on baboon BOLD fMRI of visual and somatosensory/motor. 1191. Using T1 Map to Guide Functional MRI Study of Ipsilateral Somatosensory Cortex in Awake Non-Human Primates Junjie V. Liu1, Nicholas A. Bock2, Ara Kocharyan1, Julie Mackel1, Afonso C. Silva1 1NINDS, National Institutes of Health, Bethesda, MD, United States; 2Medical Physics, McMaster University, Hamilton, ON, Canada By combining BOLD fMRI with T1 mapping, here we study the ipsilateral responses in somatosensory cortex of awake marmosets. Our results show a surprising spatial mismatch between contralateral and ipsilateral representations of the same body part. 1192. Fine -Scale Functional Connectivity Network Revealed at High Field (9.4T) Within Somatosensory Cortices of Anesthetized New World Monkeys Arabinda Mishra1, Baxter P. Rogers1, Barbara Dillenburger1, Kevin Wilson1, Feng Wang1, John C. Gore1, Li Min Chen1 1Radiology & Radiological Science, VUIIS, Nashville, TN, United States Correlations between resting state BOLD signals in widely distributed brain regions is a key signature of consciously driven mental activity in humans. In this work we attempted to explore if a fine scale functional connectivity can be detected within the anatomically well defined primary somatosensory cortex (SI) at high field and whether the functional connectivity reflects anatomical hierarchical relationships in anesthetized monkeys. We found that functional connectivity exists among anatomically interconnected cortical subregions (areas 3a, 3b, 1 and 2) within SI without the involvement of consciousness (or alertness), and the strengths of the correlation among these subregions reflect the strength of their underlying anatomical connections. 1193. fMRI Analysis of the Olfactory Responses to Home-Stream Water in Sockeye Salmon Hiroshi Bandoh1, Ikuhiro Kida2, Hiroshi Ueda1,3 1Division of Environmental Science Development, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan; 2Integrated Neuroscience Research Team, Tokyo Institute of Pschiatry, Setagaya-ku, Tokyo, Japan; 3Laboratory of Aquatic Ecosystem Conservation, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Hokkaido, Japan The odor-information processing involved in olfactory imprinting and homing of the home-stream odor in the central nervous system of salmon has not been completely elucidated. In this study, to investigate this information-processing mechanism, we used BOLD fMRI to measure the response to home-stream water in the olfactory bulb and telencephalon of sockeye salmon. The presence of BOLD signals in the dorsal area of the telencephalon indicated that the odor information for home-stream water was processed in a specific area in the telencephalon of sockeye salmon. 1194. Evaluation of Functional Deficit and Recovery in the Rat Somatosensory Cortex After Moderate Traumatic Brain Injury Using FMRI Juha-Pekka Niskanen1,2, Antti Airaksinen1, Jari Nissinen1, Asla Pitkänen1, Olli Gröhn1 1Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland; 2Department of Physics, University of Kuopio, Kuopio, Finland Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In this study, 10 rats with TBI and 6 sham operated controls were imaged during electrical stimulation of the forepaws before TBI and 1, 2 and 8 weeks after TBI. fMRI with forepaw stimulation was able to reveal functional deficit after TBI in the somatosensory cortex outside of the main lesion and also detect partial sensory recovery 8 weeks after TBI. The results suggest that fMRI could serve as a non-invasive user independent tool to evaluate functional recovery after TBI. 1195. Complexity in the Spatiotemporal Hemodynamic Response to Sensory Stimulation in the Un-Anesthetized Rat Christopher James Martin1, Jason Berwick2, Ying Zheng2, John Mayhew2 1Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom; 2University of Sheffield 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 Martin1, R Godinez1, Alfredo O. Rodriguez1 1Departament 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 Yang1, Zhiyong Xie1, James Goodman1, Anne Burkholder2, Nancy Poy2 1BioImaging COE, Pifizer Global Research & Development, Groton, CT, United States; 2WW 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 Bosshard1, Christof Baltes1, Markus Rudin1,2 1Institute for Biomedical Engineering, ETH Zürich, Zurich, Switzerland; 2Institute 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 Just1,2, Hanne Frenkel3, Rolf Gruetter3,4 1LIFMET, CIBM, EPFL, Lausanne, Switzerland; 2Department of Radiology, UNIL, Lausanne, Switzerland; 3LIFMET, EPFL, Lausanne, Switzerland; 4Department 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 Pawela1,2, Bharat B. Biswal3, Rupeng Li2, Anthony G. Hudetz4, Hani S. Matloub1, James S. Hyde2 1Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, United States; 2Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 3Department of Radiology, University of Medicine and Dentistry of New Jersey, Newark, NJ, United States; 4Department 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. 1201. Investigating the Role of Transcallosal Projections in Mediating Neuroplasticity Following Injury in a Rat Using FMRI Jennifer I. Wood1,2, Suresh E. Joel1,3, Michael T. McMahon1,2, James J. Pekar1,2, Galit Pelled, 2,4 1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States; 2The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 3The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 4F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute , Baltimore, MD, United States Human and animal studies suggest the involvement of the transcallosal projection in shaping neuroplasticity following injury may be crucial in dictating the rehabilitation probability. This study was designed to investigate the role of the transcallosal pathways in mediating neuroplasticity following injury in a rat model of sensory deprivation. Using fMRI, we have studied the time course and the age-dependency of which the transcallosal projections effect cortical reorganization. The results demonstrate that the transcallosal projections involvement in neuroplasticity varies dependent on the age and the time following the injury and may introduce a critical consideration when choosing the right rehabilitation strategy. 1202. BOLD FMRI Assessment of the Functional Response to Taste Stimulation in Rat Brain Ikuhiro Kida1, Yoko Hoshi1, Yoshinobu Iguchi1 1Integrated Neuroscience Research Team, Tokyo Institute of Pschiatry, Setagaya-ku, Tokyo, Japan Some aspects of taste information processing have not been conclusively clarified, such as the process by which the gustatory cortex uses spatial codes to characterize taste information.We used BOLD fMRI measurements obtained at 7 T in an animal system to investigate the process by which taste information is encoded. Sucrose yielded a reproducible BOLD signal increase in the gustatory cortex. During taste stimulation, BOLD signals were also detected in the lip region of the primary somatosensory cortex, secondary somatosensory cortex, and amygdalae. This is the first study that used BOLD fMRI to observe gustatory activation in the rat brain. 1203. Functional MRI of Cortico-Striato-Thalamal Circuit Using a Novel Flexible Polyimide-Based Microelectrode Array Implanted in Rodent Deep Brain Pai-Feng Yang1, You-Yin Chen2, Jyh-Horng Chen1, Chen-Tung Yen3 1Electrical Engineering, National Taiwan University, Taipei, Taiwan; 2Electrical Engineering, National Chiao-Tung University, Hsinchu, Taiwan; 3Zoology, National Taiwan University, Taipei, Taiwan This paper proposes a novel flexible MRI-compatible microelectrode array that leverages the stimulation and recording properties for neuroscience application. We perform functional MRI to investigate the cortico-striato-thalamal circuit with thalamic stimulation. Significant positive BOLD responses were observed in receptive field in upper lip region (S1ULp), barrel field (S1BF) and secondary somatosensory cortex (S2). Negative BOLD responses were revealed in caudate putamen (CPu). We inferred a limbic cortico-striatal loop might exist. 1204. A Non Invasive Experimental Protocol for FMRI Studies: Investigation of the Basal Ganglia-Cortex Circuit in a Rat Model Salem Boussida1, Amidou Traore2, Jean-Pierre Renou2, Franck Durif3 1INRA, UR370 QuaPA/NMR plateforme, Centre Clermont-Ferrand/Theix, F-63122 Saint Genès Champanelle, France; 2INRA, UR370 QuaPA/NMR plateforme, Centre Clermont-Ferrand/Theix, F-63122 Saint Genès Champanelle, France; 3CHU Clermont-Ferrand, Service de Neurologie, Clermont-Ferrand, F-63001, France. Combination of blood– oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) and electrical hindpaw stimulation has been used as a standard model to study the somatosensory pathway and brain rehabilitation in rats. In the present study, we examined the feasibility of performing BOLD fMRI experiments on rat to investigate the activity of the basal ganglia (BG)-cortex circuit associated to hindpaw sensitive stimulation. These findings will have relevance in the fMRI studies dealing with physiopathology of neurodegenerative diseases such as Parkinson 1205. Refining the Sensory and Motor Ratunculus of the Rodent Upper Extremity: Evaluation of the C7 Nerve Root Using FMRI and Direct Nerve Stimulation Patrick C. Hettinger1, Rupeng Li2, Ji-Geng Yan1, Hani S. Matloub1, Young R. Cho1, Matthew L. Runquist2, Christopher P. Pawela1, James S. Hyde2 1Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, United States; 2Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States The purpose of this study is to further define the ratunculus by observing cortical activity using BOLD fMRI during direct stimulation of the C7 nerve root. In this study, 7 Sprague-Dawley rats underwent implantable electrode placement on the C7 nerve root. BOLD response to nerve stimulation was then studied using a Bruker 9.4T MRI scanner. C7 nerve stimulation resulted in a small amount of activation in the S1FL region along with a large amount of activation within the M1/M2 regions. These findings are similar to the sensory and motor distributions described in human C7 nerve root literature. 1206. Functional MRI Detects Chronically Enhanced Somatosensory Activation Maps Following Multiple Seizures in Rats. Ursula I. Tuor1, Jennifer Vuong2, Jeffrey F. Dunn3, Tadeusz Foniok1, Dave Kirk4, Amy H. Henderson2, G Campbell Teskey2,5 1Institute for Biodiagnostics (West), National Research Council of Canada , Calgary, Alberta, Canada; 2Psychology, University of Calgary; 3Radiology, University of Calgary; 4Experimental Imaging Centre, University of Calgary; 5Anatomy and Cell Biology, University of Calgary, Calgary, Alberta, Canada We used functional magnetic resonance imaging (fMRI) in rats to investigate whether following 20 repeatedly elicited seizures there are seizure-induced alterations in the somatosensory maps to forepaw stimulation. We observed increased areas of activation both acutely (1-3 days) and chronically (3-5 weeks) after experimental kindling induced epilepsy. The data indicate that there is considerable neuroplasticity and development of new pathways during the progression of epilepsy. Whether comparable plasticity of cortical maps is present in humans should be tested using fMRI in future studies, considering that such seizure-induced changes may be involved in producing interictal behavioural disturbances. 1207. Layer-Specific FMRI of Photic Stimulation in the Rat Retina at 11.7 T Yen-Yu Ian Shih1, Bryan H. De La Garza1, William J. Lavery1, Eric R. Muir1,2, Timothy Q. Duong1 1Research Imaging Institute, Ophthalmology/Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States; 2Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States The retina is about 276 micron thick including the choroid and has highly organized laminar structures. This study reports, for the first time, the feasibility of high-resolution blood-volume fMRI to image layer specific (retinal and choroidal) visual responses in the rat retina at 11.7T up to 40x40x600 micron nominal resolution. Given that the choroid is behind the retina and the retinal pigment epithelium, it is generally inaccessible by optical techniques. Blood-volume fMRI thus could provide a unique means to evaluate lamina-specific functional changes in the rat retina where many retinal disease models are readily available. 1208. Pass-Band Balanced Steady State Free Precession Functional MRI of the Mouse Retina Eric Raymond Muir1,2, Sung-Hong Park3, Timothy Q. Duong2 1Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States; 2Research Imaging Institute, Ophthalmology/Radiology, UT Health Science Center San Antonio, San Antonio, TX, United States; 3Research Imaging Institute, Radiology, UT Health Science Center San Antonio, San Antonio, TX, United States BOLD fMRI of the thin retina with the widely used EPI acquisition is challenging because the eye is a region of large magnetic inhomogeneity and high-resolution EPI is pushing the limits of gradient performance, resulting in susceptibility-induced signal drop out and image distortion. To overcome these limitations, we implemented a pass-band balanced steady state free precession (bSSFP) sequence for fMRI of the mouse retina at 45x45x500 µm. bSSFP has comparable temporal resolution and SNR per unit time as EPI, without the artifacts common in EPI. bSSFP fMRI could reliably detect layer-specific responses to hypoxic challenge in the mouse retina. 1209. Simultaneous FMRI and Long-Term in Vivo Electrochemistry (LIVE): Identifying the Neurochemical Correlates of Functional Imaging Signals John Lowry1, Karen Griffin2, Stephen McHugh3, Nicola Sibson4 1Department of Chemistry, National University of Ireland, Maynooth, Ireland; 2University College Dublin, Ireland; 3Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom; 4Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom Long-term in-vivo electrochemistry (LIVE) enables real-time measurement of brain metabolites. Here we have simultaneously obtained BOLD fMRI and amperometric LIVE tissue oxygen data from rat cerebral cortex, during both increases and decreases in inspired oxygen. BOLD and tissue oxygen measurements demonstrated close correlation during both complete oxygen removal (negative responses) and increases in inspired oxygen (positive responses). Our findings demonstrate the feasibility of obtaining real-time metabolite information during fMRI acquisition. The results show that the BOLD signal provides a close correlate of the tissue oxygen dynamics or, alternatively, that tissue oxygen concentration can predict the magnitude of the BOLD response. 1210. Evaluation of Cerebral Energy Demand During Graded Hypercapnia Stefan Alexandru Carp1, Maria Angela Franceschini1, David Alan Boas1, Young Ro Kim1 1Martinos Center/Radiology, Massachusetts General Hospital, Charlestown, MA, United States The cerebral metabolic rate of oxygen (CMRO2) is a physiological parameter closely linked to neural activation as well as to various disease states. Hypercapnic calibration is used to calibrate the BOLD-CBF-CBV relationship under the assumption of iso-metabolic blood flow increase during CO2 inhalation. Simultaneous near infrared optical measurements of cerebral blood volume, blood flow and oxygen extraction can also be used to monitor CMRO2 changes, albeit at low spatial resolution. We use these optical measurements during graded hypercapnia to test the iso-metabolic assumption, and demonstrate an apparent increase in brain metabolism at higher inhaled CO2 levels. 1211. Dissociation of BOLD and Local Field Potentials Wen-Ju Pan1, Matthew Magnuson1, Garth Thompson1, Waqas Majeed1, Dieter Jaeger2, Shella Keilholz1 1BME, Georgia Institute of Technology / Emory University, Atlanta, GA, United States; 2Biology, Emory University, Atlanta, GA, United States To examine what extent consistence of the measurements between BOLD fMRI and local field potential (LFP), we evaluated BOLD and LFP simultaneously in rat somatosensory cortex with a combined measurement technique. The preliminary results indicated a dissociation between BOLD and LFP during low-level neural activity, which might mirror the limitation of neurovascular coupling, the bridge between BOLD and neural activity. 1212. TR and TE Dependence on Low Frequency BOLD Fluctuations Matthew Evan Magnuson1, Wenju Pan1, Waqas Majeed1, Garth Thompson1, Shella Keilholz1 1Biomedical Engineering, Georgia Institute of Technology / Emory University, Atlanta, GA, United States Low freqnecy fluctuations in resting state BOLD data have often been used to map functional connectivity in the rat brain. These low frequency BOLD fluctuations contain contributions from CBF, CBV, and CMRO2. Each of these components have unique physiological time signatures and effective echo times; therefore, modification of the TR and TE used in resting state scans should result in altered contributions from each BOLD component. In this study we examine the dependence of the selection of the TR and TE variables on low frequency resting state data. 1213. Further Test and Validation of Saturation-Recovery T1 MRI Measurement for Imaging Absolute CBF Change Xiao Wang1, Xiao-hong Zhu1, Yi Zhang1, Wei Chen1 1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States The feasibility of saturation-recovery T1 MRI for imaging and quantifying absolute CBF change was further tested at 9.4T using a rat hypercapnia model on two aspects: using diffusion gradients to investigate macrovascular inflow contribution; and slab saturation with varied thickness to test the effects of blood transit distance on measuring CBF. The results indicate that the outcomes of CBF changes induced by hypercapnia were coincident with the literature reports, and not significantly affected by large-vessel inflow effect and blood transit time. The overall results demonstrate that the saturation-recovery T1 MRI is sensitive to microvascular perfusion; it provides a noninvasive and reliable imaging approach for studying cerebral perfusion changes induced by physiology or pathology perturbation. 1214. In Vivo MR Measurement of Arterial Pulse Pressure in the Murine Aorta Volker Herold1, Marco Parczyk1, Wolfgang Rudolf Bauer2, Eberhard Rommel1, Peter Michael Jakob1 1Department of Physics EP5, University of Wuerzburg, Wuerzburg, Bayern, Germany; 2Medizinische Universitätsklinik, University of Wuerzburg, Wuerzburg, Bayern, Germany Mouse models are increasingly used to investigate functional and cardiovascular parameters. In this work we present an approach to noninvasively estimate the arterial pulse pressure by measuring the time dependant blood flow pulse and the local pulse wave velocity. By determining the complex impedance with solutions from the Navier-Stokes equations for incompressible fluids, the pressure pulse could be calculated from the accordant flow pulse. The present results are in good agreement with results from the literature obtained by invasive methods. 1215. Problems for Motion Correction: Paradigm Correlated Motion Remains a Confounding Source for FMRI Artefacts. Lubos Budinsky1, Benito de Celis Alonso2, Marina Sergejeva1, Andreas Hess2 1Institute of Pharmacology, FAU, Erlangen, Germany; 2Institute of Pharmacology, FAU, Erlangen, Germany The undesired motion, which is correlated with the fMRI paradigm (often present in experiments which are using mechanical stimulation or painful stimulus) can create false areas of an activity, which could remain real BOLD activity areas and a signal time course. Here we present series of fMRI experiment with phantoms and dead animals to which the motion was induced by using an air driven device integrated into the animal cradle. Using results from these experiments we suggest strategy, how to deal with this problem even if conventional motion correction algorithm are not able to remove these false areas completely. 1216. Functional MRI in the Rat at 9.4 T and 16.4 T David Zsolt Balla1, Hannes M. Wiesner1, Gunamony Shajan1, Rolf Pohmann1 1High Field Magnetic Resonance Center, Max Planck Insitute for Biological Cybernetics, Tübingen, Baden-Württemberg, Germany Functional MRI (fMRI) in animals at high magnetic fields keeps expanding our knowledge about the basics of neural processing but the specificity of the fMRI-signal is still under ongoing investigation. Yet, as the signal to noise ratio in MRI depends linearly on the magnetic field strength and calls for even stronger magnets for the detection of even smaller anatomical details, the relation between the functional MR-response and field strength can only be approximated with complex models. In this study the blood oxygenation dependent (BOLD) effect was measured and compared at 9.4 T and 16.4 T in the same animal with segmented gradient-echo (GE) and spin-echo (SE) echo planar imaging (EPI) sequence using optimal echo times for the respective field. Furthermore, high resolution fMRI acquisition at 16.4 T was performed up to a 50 µm in-plane accuracy and for an 8 s temporal resolution without the use of cryo-coils or coil-arrays. 1217. BOLD, CBV, and CBF FMRI of Caudate Putamen in Rat Brain During Noxious Electrical Stimulation: Its Negative Hemodynamic Response to Neural Activities Fuqiang Zhao1, Denise Welsh1, Mangay Williams1, Alexandre Coimbra1, Mark O. Urban2, Richard Hargreaves2, Jeffrey Evelhoch1, Donald S. Williams1 1Imaging Department, Merck Research Laboratories, West Point, PA, United States; 2Neuroscience Department, Merck Research Laboratories, West Point, PA, United States In central nervous system, neuronal activity generally leads to increases in local venous blood oxygenation level (BOLD), cerebral blood flow (CBF), and cerebral blood volume (CBV). However, previous studies have reported that the neural activity in rat caudate putamen (CPu) during noxious electrical stimulation (NES) of paws causes BOLD and CBV decreases. To further understand the specific hemodynamic response in this anatomical structure and its temporal characteristics, BOLD, CBV, and CBF fMRI studies were performed in a rat brain slice containing the CPu. Our results suggest that the neural activity in the CPu during NES causes decreases in CBV and CBF, and an increase in CMRO2 which lasts >2 minutes after stopping the NES. 1218. fMRI at 17.6 T and Optical Fiber-Based Ca2+-Imaging in Rodents Albrecht Stroh1, Florian Schmid2, Afra Wohlschlaeger3, Valentin Riedl4, Jenny Kressel3, Cornelius Faber2 1Department of Neuroradiology, Technical University Munich, Munich, Germany; 2Institute for Clinical Radiology, University Hospital Münster, Münster, Germany; 3Department of Neuroradiology, Technical University Munich, Germany; 4Department of Neurology, Technical University Munich, Germany n this study we tested the feasibility of rat fMRI at highest field strength in combination with an implanted optical fiber. We aim for the combination of fiber based optical Ca2+ imaging with functional magnetic resonance imaging (fMRI) at 17.6 T in vivo. We increased the temporal resolution of fMRI to 20 ms by applying k-space segmentation. Additionally, we conducted fiber-based Ca2+ imaging in mice upon electric forepaw stimulation, detecting neuronal population activity. Our study indicates that a multimodal approach combining a global method like fMRI with a spatially confined, highly specific method as optical Ca2+ imaging becomes amenable. 1219. Layer Specific Detection of Inhibitory FMRI Response in Somatosensory Cortex Through Cortico-Cortical Interaction in Rats Yoshiyuki Hirano1, Alan P. Koretsky2, Afonso C. Silva1 1CMU, LFMI, NINDS, NIH, Bethesda, MD, United States; 2FMMS, LFMI, NINDS, NIH, Bethesda, MD, United States We investigated the laminar dependence of cortico-cortical interactions induced by paired bi-lateral somatosensory stimulation in α-chloralose anesthetized rats. When compared to the response obtained at 0 ms ISI, the BOLD percent signal change in the S1FL responding to the late stimulus was decreased by 47 % at 40 ms ISI. The degree of suppression in layers III to V was stronger than suppression of fMRI changes in layers I-II and in bottom of layer VI. Our data shows that BOLD fMRI has sufficient spatial and temporal resolution to study cortical circuits, within functional columns and layers. Yüklə 4,25 Mb. Dostları ilə paylaş:
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