Slow vasomotor fluctuation in fMRI of anesthetized child brain

Signal intensity changes in fMRI during rest caused by vasomotor fluctuatio ns were investigated in this work. Resting-state baseline fluctuations were evaluated in 12 children anesthetized with thiopental, Five subjects had f luctuations related to subvoxel motion. In seven subjects without significa nt motion, slow signal fluctuation at 0.025-0.041 Hz near one or more prima ry sensory cortices was observed. In each subject the amplitude and frequen cy of the fluctuations were stable. It is hypothesized that thiopental, whi ch reduces blood pressure and flow in the cortex, alters the feedback in ne urovascular coupling leading to an increase in the magnitude and a reductio n in the frequency of these fluctuations. The use of anesthesia in fMRI may provide new insight into neural connectivity and the coupling of blood flo w and neural metabolism. (C) 2000 Wiley-Liss, Inc.