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A hypercapnia‐based normalization method for improved spatial localization of human brain activation with fMRI
Author(s) -
Bandettini Peter A.,
Wong Eric C.
Publication year - 1997
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/(sici)1099-1492(199706/08)10:4/5<197::aid-nbm466>3.0.co;2-s
Subject(s) - hypercapnia , normalization (sociology) , blood oxygenation , hemodynamics , oxygenation , voxel , blood volume , blood oxygen level dependent , spatial normalization , hypoxia (environmental) , neuroscience , haemodynamic response , resting state fmri , functional magnetic resonance imaging , cardiology , chemistry , medicine , psychology , blood pressure , oxygen , heart rate , radiology , respiratory system , organic chemistry , sociology , anthropology
An issue in blood oxygenation level dependent contrast‐based functional MRI is the accurate interpretation of the activation‐induced signal changes. Hemodynamic factors other than activation‐induced changes in blood oxygenation are known to contribute to the signal change magnitudes and dynamics, and therefore need to be accounted for or removed. In this paper, a general method for removal of effects other than activation‐induced blood oxygenation changes from fMRI brain activation maps by the use of hypercapnic stress normalization is introduced. First, the effects of resting blood volume distribution across voxels on activation‐induced BOLD‐based fMRI signal changes are shown to be significant. Second, the effects of hypercapnia and hypoxia on resting and activation‐induced signal changes are demonstrated. These results suggest that global hemodynamic stresses may be useful for non‐invasive mapping of blood volume. Third, the normalization technique is demonstrated. © 1997 John Wiley & Sons, Ltd.