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Advances in MRI to probe the functional and structural network of the macaque brain

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dc.contributor.advisor Wim Vanduffel and David Tuch. en_US
dc.contributor.author Khachaturian, Mark Haig, 1979- en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering. en_US
dc.date.accessioned 2009-03-16T19:42:45Z
dc.date.available 2009-03-16T19:42:45Z
dc.date.copyright 2007 en_US
dc.date.issued 2007 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/44785
dc.description Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007. en_US
dc.description Includes bibliographical references (leaves 95-103). en_US
dc.description.abstract Diffusion MRI and fMRI have provided neuroscientists with non-invasive tools to probe the functional and structural network of the brain. Diffusion MRI is a neuroimaging technique capable of measuring the diffusion of water in neural tissue. It can reveal histological architecture irresolvable by conventional magnetic resonance imaging methods and has emerged as a powerful tool to investigate a wide range of neuropathologies. fMRI is a neuroimaging technique sensitive to hemodynamics which is indirectly linked to neural activity. Despite the applications of diffusion MRI and fMRI in basic and clinical neuroscience, the underlying biophysical mechanisms of cerebral diffusion and the hemodynamic response remain largely unknown. Also, these neurotechnqiues suffer from low SNR compared to conventional MRI. The challenges associated with the acquisition and interpretation of diffusion MRI and fMRI limit the application of these powerful non-invasive neuroimaging tools to study the functional and structural network of the brain. The purpose of this thesis is three fold; (1) improve the acquisition and reconstruction of the diffusion MRI and fMRI signals and (2) develop an MR-compatible cortical cooling system to reversibly deactivate cerebral glucose metabolism, and (3) apply the cortical cooling system to investigate the effect of cerebral glucose metabolism on cerebral diffusion and the hemodynamic response. First, I describe a novel phased array monkey coil capable of improving the resolution of diffusion MRI (4 fold increase) and fMRI (2 fold increase) in monkeys. Secondly, I present a novel reconstruction method to resolve complex white matter architecture which boosts the sampling efficiency of the diffusion MRI acquisition by 274-377%. en_US
dc.description.abstract (cont.) Thirdly, I present a MR-compatible cortical cooling system capable of reversibly deactivating cerebral metabolism in monkeys. The cortical cooling system has been applied to study the effect of cerebral glucose metabolism on the cerebral diffusion of water. I use MR temperature maps to quantify the region and degree of deactivation (accuracy of ±1 °C in vivo). Then, I show that reversible deactivation of cerebral glucose metabolism affects the magnitude of cerebral diffusion (12-20%) but not the anisotropy. Finally, I apply the cortical cooling system to study the effect of reversibly deactivating cerebral glucose metabolism in V1 and its effect on the hemodynamic response in the visual system. Reversible deactivation of V1 decreased the hemodynamic response in visually driven regions upstream and downstream from V1. Compensatory effects were observed in V1 in both hemispheres and ipsilateral TEO with in 2 minutes of deactivation. Here I have described the tools to probe the functional and structural network of the macaque brain. en_US
dc.description.statementofresponsibility by Mark Haig Khachaturian. en_US
dc.format.extent 106 leaves en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582 en_US
dc.subject Nuclear Science and Engineering. en_US
dc.subject.lcsh Magnetic resonance imaging en_US
dc.title Advances in MRI to probe the functional and structural network of the macaque brain en_US
dc.title.alternative Advances in magnetic resonance imaging to probe the functional and structural network of the macaque brain en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering. en_US
dc.identifier.oclc 300301097 en_US


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