Anna Leigh Rack-Gomer1, Tom T. Liu1
Center for Functional MRI, UC
Prior work has shown that caffeine decreases the amplitude and correlation of resting-state BOLD fluctuations. However, the physiological mechanisms by which caffeine alters spontaneous BOLD fluctuations remain unclear. In this study, we show that the ratio of the amplitudes of resting-state BOLD and cerebral blood flow (CBF) fluctuations in the motor cortex is reduced by caffeine. This finding indicates that caffeine tightens the coupling between resting-state fluctuations in CBF and oxygen metabolism. Tighter flow-metabolism coupling is consistent with the caffeine-induced decrease in the amplitude of spontaneous BOLD fluctuations and may also contribute to the reduced resting-state BOLD connectivity.