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An Introduction to Normalization and Calibration Methods in Functional MRI

Published online by Cambridge University Press:  01 January 2025

Thomas T. Liu ,
Gary H. Glover ,
Bryon A. Mueller ,
Douglas N. Greve  and
Gregory G. Brown
Thomas T. Liu*
Affiliation:
Center for Functional MRI, University of California San Diego
Gary H. Glover
Affiliation:
Department of Radiology, Stanford University
Bryon A. Mueller
Affiliation:
Department of Psychiatry, University of Minnesota
Douglas N. Greve
Affiliation:
Department of Radiology, Massachusetts General Hospital
Gregory G. Brown
Affiliation:
VA San Diego Healthcare System and Department of Psychiatry, University of California San Diego
*
Requests for reprints should be sent to Thomas T. Liu, Center for Functional MRI, University of California San Diego, 9500 Gilman Drive, MC 0677, La Jolla, CA 92093, USA. E-mail: ttliu@ucsd.edu
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Abstract

In functional magnetic resonance imaging (fMRI), the blood oxygenation level dependent (BOLD) signal is often interpreted as a measure of neural activity. However, because the BOLD signal reflects the complex interplay of neural, vascular, and metabolic processes, such an interpretation is not always valid. There is growing evidence that changes in the baseline neurovascular state can result in significant modulations of the BOLD signal that are independent of changes in neural activity. This paper introduces some of the normalization and calibration methods that have been proposed for making the BOLD signal a more accurate reflection of underlying brain activity for human fMRI studies.

Keywords

functional MRIarterial spin labelingcerebral blood flowquantitative fMRIcalibrated fMRIhypercapnia
Type
Original Paper
Information
Psychometrika , Volume 78 , Issue 2 , April 2013 , pp. 308 - 321
Copyright
Copyright © 2012 The Psychometric Society

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