Fig. 7.

Influence of blockade of receptors for serotonin with methysergide (M) upon activities of the phrenic nerve (∫Phr) and hypoglossal nerve (∫Hyp) in E and G in the mouse. Note that in E, hypoglossal discharge was linked to the phrenic burst, but periodical bursts of hypoglossal activity were recorded in neural expiration. Following administration of 3.0 μM of M, phrenic and hypoglossal discharges were largely uncoupled. In G, phrenic and hypoglossal discharges were linked, although burst of hypoglossal discharge in neural expiration was seen. Small, high-frequency oscillations, which are visible on ∫Phr activity, represent the electrocardiogram.