The technique of reversible cold block was used to explore the possibility that the trigeminal subnucleus caudalis (Vc) influences the responses of rostral trigeminal brainstem nuclear complex (TBNC) neurons to stimulation of the cerebrovasculature. Reversible cold block of Vc was found to abolish totally the responses of many rostral TBNC neurons to stimulation of the cerebrovasculature. The remaining neurons were not affected by the cold block. These data suggest that some rostral TBNC neurons may receive an indirect input from the cerebrovasculature via Vc while other rostral TBNC neurons receive a direct input from the cerebrovasculature.