Comparative aspects of raphé-induced modulation of evoked and spontaneous cerebellar unit activity.

Electrical activation of the raphé complex predominantly inhibits spontaneous firing of randomly encountered Purkinje cells. These experiments were performed to compare the effects of raphé stimulation upon spontaneous and evoked climbing and mossy fiber inputs, as well as GABA-mediated inhibition of Purkinje cells. The findings revealed a preferential inhibitory influence of the raph nuclei on evoked simple and complex activity rather than spontaneous firing of Purkinje cells. Furthermore, the raphé appears to augment GABAergic "off-beam" inhibition of Purkinje cells.