Changes in brain cellular activity are accompanied almost invariably by changes in the local cerebral blood flow (CBF). In most functional imaging studies, the increase in local blood flow is assumed to correlate with an increase in the net spike activity of the neurons in the activated region. The question raised in this work is whether the increase in perfusion correlates to spike activity or synaptic transmission, or both. By utilizing measurements of neuronal activity, i.e., single-cell spike activity and synaptic activity of ensembles of neurons (i.e., field potentials), we were able to show that activity-dependent increases in CBF are independent of spiking activity; however, it can be explained by active and passive pre- and postsynaptic mechanisms distinct from spiking. Our work has primarily been focused on the cerebellar cortex where CBF was monitored by laser-Doppler flowmetry and neuronal activity was measured using a glass electrode positioned close to the Purkinje cell.