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Physiological basis for BOLD MR signal changes due to neuronal stimulation: Separation of blood volume and magnetic susceptibility effects
Author(s) -
Kennan Richard P.,
Scanley B. Ellen,
Innis Robert B.,
Gore John C.
Publication year - 1998
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910400609
Subject(s) - stimulation , blood volume , blood oxygen level dependent , signal (programming language) , nuclear magnetic resonance , chemistry , magnetic resonance imaging , volume (thermodynamics) , neuroscience , medicine , functional magnetic resonance imaging , biology , physics , radiology , computer science , programming language , quantum mechanics
Abstract An NMR method is applied for separating blood volume and magnetic susceptibility effects in response to neuronal stimulation in a rat model. The method uses high susceptibility contrast agents to enhance blood volume induced signal changes. In the absence of exogenous agent, the dominant source of signal change on neuronal activation is associated with the signal increase from the blood oxygen level dependent (BOLD) effect. The relative negative contribution of blood volume changes to BOLD changes is maximally estimated to be 34%. The blood volume changes associated with median nerve stimulation (7 Hz) in the motor cortex are 26 ± 7% and the corresponding blood susceptibility changes are 0.021 ± 0.006 ppm. These methods can be applied to enhance the sensitivity of fMRl signal response and provide accurate quantitative measures of blood volume response to stimulation.