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Abstract #3338

Testing Whether the Brain Flow-Metabolism Coupling Ratio Is the Same for Two Different Stimulus Responses Without a Calibration Experiment

Valerie E M Griffeth1, Nicholas P. Blockley2, Aaron Simon3, Richard B. Buxton4

1Bioengineering, University of California San Diego, La Jolla, CA, United States; 2FMRIB, University of Oxford, Oxford, United Kingdom; 3Bioengineering, University of California, San Diego, La Jolla, CA, United States; 4Radiology, University of California San Diego, La Jolla, CA, United States

The simple and straightforward ratio method can be used test whether the CBF-CMRO2 coupling ratio is the same for two different stimulus responses using only combined CBF and BOLD measurements, independent of model parameters, and without an additional calibration experiment. We tested the ratio method using a previously published detailed BOLD model demonstrating that it is an effective approach for comparing stimulus responses in order to differentiate between values of CBF-CMRO2 coupling. We also include a reanalysis of recently published data on varying visual stimulus contrast showing consistency of these results in comparison to the traditional Davis model approach.

Keywords

absolute accuracy activation activity added although analyze analyzing applying around arterial assumes audience bioengineering black blood blue bold brain calibrated calibration capillaries cerebral combination combined comparable comparing complexity consistent constant constants containing contrast coupling decay definite density departure detailed deviation differs diminishing directly dots easily effective energetic even exact examine examining experiment experimental explore extraction flow form fraction full function good growing grows heuristic highly hypothesis identity implying importantly include includes independent indicates inspired instead kingdom linear lumped make mathematical measured metabolic metabolism model necessary necessitating needed nonlinear null oxford oxygen paper physiological plot predict predicted previously prior process produce produces production propose published pure rank reasonable recent relating relationship remains required response responses resting separate separation sets sign significance significantly simple simpler simplicity simulate simulations smaller specifically stimulus straightforward studies subject suited supplying taken taking tends term terms toward type typical uniquely variability variation varies venous versus visual volume whether