Kannurpatti Sridhar S, Biswal Bharat B, Hudetz A G
Department of Radiology, UMDNJ-New Jersey Medical School, Newark, New Jersey 07103, USA.
J Magn Reson Imaging. 2003 Jun;17(6):641-7. doi: 10.1002/jmri.10311.
To examine the regional blood oxygenation level-dependent (BOLD) signal response to rapid changes in arterial oxygen tension.
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.
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.
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).
研究动脉血氧张力快速变化时局部脑血流灌注依赖（BOLD）信号的反应。
对5只戊巴比妥钠麻醉的雄性Sprague-Dawley大鼠进行功能磁共振成像（fMRI）。大鼠接受不同时长的呼吸暂停，作为一种快速、分级且可逆的低氧-高碳酸血症刺激。在大鼠脑的大脑皮层、海马体、第三脑室和丘脑逐像素研究BOLD信号反应的动态变化。
呼吸暂停在所有研究的脑区均引起BOLD信号下降，其幅度随刺激时长增加而增大。恢复正常通气后，信号恢复至呼吸暂停前的基线水平。观察到BOLD信号动态变化存在区域差异，海马体中BOLD信号变化幅度最小，其次是丘脑、大脑皮层和第三脑室有相对较大的变化。对每个像素估计刺激开始后信号变化的时间（t(0)）。生成的时间延迟图显示海马体中的起始时间值最高，其次是丘脑、大脑皮层和第三脑室。
大脑中BOLD信号响应呼吸暂停的区域动态变化除脑血流量（CBF）外，可能还取决于氧代谢率。
