The raphe obscurus projects to the cerebellar lobes VI and VII and to crus II along with the nucleus raphe pontis . This so called obscure nucleus has also been implicated in the modulation of the hypoglossal nerve. It has been observed that the ablation of this nucleus causes a change in the firing pattern in the XII nerve . In addition, the raphe obscurus mediates expiration via the inhibitory effect of serotonin and depresses periodic synaptic potentials . It has also been shown that this nucleus stimulates gastrointestinal motor function; microinjections of 5-HT into the n.r. obscurus increase gastric movement . [WP,unvetted]. [ http://en.wikipedia.org/wiki/Nucleus_raphe_obscurus ]