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Regional dynamics of the fMRI‐BOLD signal response to hypoxia‐hypercapnia in the rat brain
Author(s) -
Kannurpatti Sridhar S.,
Biswal Bharat B.,
Hudetz A.G.
Publication year - 2003
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.10311
Subject(s) - thalamus , hypercapnia , cerebral blood flow , apnea , gyrus , cerebral cortex , ventricle , neuroscience , medicine , hypoxia (environmental) , stimulus (psychology) , blood oxygen level dependent , anesthesia , cardiology , functional magnetic resonance imaging , psychology , chemistry , oxygen , acidosis , psychotherapist , organic chemistry
Purpose To examine the regional blood oxygenation level‐dependent (BOLD) signal response to rapid changes in arterial oxygen tension. Materials and Methods Functional MR imaging (fMRI) was carried out in five male Sprague‐Dawley rats anesthetized with Sodium Pentobarbital. Rats were subjected to different durations of apnea as a rapid, graded, and reversible hypoxic‐hypercapnic stimulus. Dynamics of the BOLD signal response were studied on a pixel‐by‐pixel basis in the cerebral cortex, hippocampus, third ventricle, and thalamus in the rat brain. Results Apnea induced a BOLD signal drop in all the brain regions studied, the magnitude of which increased with longer durations of the stimulus. The signal recovered to preapnic baseline levels after resumption of normal ventilation. Regional variation in the BOLD signal dynamics was observed with the magnitude of the BOLD signal change in the hippocampus being the least, followed by a relatively larger change in the thalamus, cerebral cortex, and third ventricle. The time ( t 0 ) for the signal change after the onset of the stimulus was estimated for every pixel. Time delay maps generated show the highest onset time values in the hippocampus followed by the thalamus, cerebral cortex, and third ventricle. Conclusion The regional dynamics of the BOLD signal in the brain in response to apnea may vary depending on the rate of oxygen metabolism in addition to cerebral blood flow (CBF). J. Magn. Reson. Imaging 2003;17:641–647. © 2003 Wiley‐Liss, Inc.