Friday, 7 may 2010
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| fMRI in Genetics & phMRI
Room K1 10:30-12:30 Moderators: Timothy Q. Duong and Christopher Pawela 10:30 704. Optogenetic Functional Magnetic Resonance Imaging (OfMRI): Genetically Targeted in Vivo Brain Circuit Mapping Jin Hyung Lee1, Remy Durand2, Viviana Gradinaru2, Feng Zhang2, Dae-Shik Kim3, Karl Deisseroth2 1Electrical Engineering, University of California, Los Angeles, Los Angeles, CA, United States; 2Bioengineering, Stanford University, Stanford, CA, United States; 3Boston University, Boston, MA, United States Despite an enormous, rapidly-growing functional brain imaging literature based on blood oxygenation level dependent (BOLD) signals, it remains controversial which classes of local activity and cellular elements (e.g., glia, axonal tracts, or excitatory neurons) can trigger BOLD responses. Using a novel methodology integrating Optogenetics with high-field fMRI, we show here that robust BOLD signal can be triggered in primary motor cortex by specific recruitment of CaMKIIa-expressing excitatory neurons. We further show that this approach allows for highly specific in vivo circuit identification, in which the functional role of cell types defined by location and genetic identity, can be directly observed and globally mapped in the living mammal. 10:42 705. Light-Induced Activation of Light-Sensitive Pumps Modulates FMRI Responses John E. Downey1,2, Piotr Walczak3,4, Suresh E. Joel1,2, Assaf A. Gilad3,4, Michael T. McMahon1,2, Heechul Kim3,4, James J. Pekar1,2, Galit Pelled, 2,5 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; 4Cellular Imaging Section, Vascular Biology Program, Institute for Cell Engineering , Johns Hopkins University School of Medicine, Baltimore, MD, United States; 5F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute , Baltimore, MD, United States Recent developments in optical-genetic (optogenetics) approaches enable immediate manipulations of neuronal firing rate by using light-induced activation of light sensitive pumps. We have engineered the excitatory neurons in rat somatosensory cortex to express halorhodopsin (light-sensitive chloride pump) using direct neuronal infection with lentivirus. Thus, in the presence of light, the chloride pumps open and trigger neuronal hyperpolarization i.e. decreases in neuronal firing rate. Consistent with electrophysiology results, light induced activation of halorhodopsin during forepaw stimulation, decreased the amplitude and the extent of fMRI responses. These results introduce an exciting and novel approach to study neuronal behavior in vivo. 10:54 706. In-Vivo Optogenetic Activation of Cortical Astrocytes with FMRI at 9.4T: OptoMRI Jack A. Wells1, Simon Walker-Samuel1, Nephtali Marina2, Melina Figueiredo3, Anja G. Teschemacher3, Michael Spyer2, Alexander V. Gourine2, Sergey Kasparov3, Mark F. Lythgoe1 1Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom; 2Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom; 3Physiology & Pharmacology, University of Bristol, Bristol, United Kingdom The relative contribution of the neuronal and glial activation to the BOLD signals is not fully established. Optogenetic techniques, in which particular brain cells are engineered to express light-sensitive ion channels, offer minimally invasive and temporally precise control of the activities of distinct cellular populations. In this study we performed simultaneous optogenetic activation of cortical astrocytes with high field fMRI . Astrocytes in the cortex of the anaesthetised rat brain were stimulated during continuous imaging using gradient echo EPI at 9.4T. Here we present our preliminary data.
Functional MRI methods have been widely applied to map regional changes in brain activity elicited by somatosensory stimuli, complex cognitive or emotional tasks, and pharmacological challenges. Here we describe and demonstrate the use of fMRI to map the functional effects of rapid and reversible pharmacogenetic silencing of selected neuronal populations focally expressed in specific regions of the mouse brain. In combination with behavioural observations, this novel approach provides a powerful means to assess the functional role of these neurons, to resolve the brain circuitry they are elements of, and to establish their implication in behavioural control 11:18 708. Pharmacological MRI and Resting-State FMRI of Functional Brain Organization in the Serotonin Transporter Knock-Out Rat Yüklə 256,39 Kb. Dostları ilə paylaş:
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