Regional dynamics of the fMRI-BOLD signal response to @entity519 -hypercapnia in the XXXX brain.

@entity26 @entity1372 @entity519 @entity35 @entity386
PURPOSE: To examine the regional blood oxygenation level-dependent (BOLD) signal response to rapid changes in arterial @entity26 tension. MATERIALS AND METHODS: Functional MR imaging (fMRI) was carried out in five male @entity35 anesthetized with @entity1372 Pentobarbital. @entity35 were subjected to different durations of @entity386 as a rapid, graded, and reversible @entity519 -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 @entity35 brain. RESULTS: @entity386 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 @entity386 may vary depending on the rate of @entity26 metabolism in addition to cerebral blood flow (CBF).
