To assess the functional meaning of the gustatory projections previously seen to converge with trigeminal and fastigial afferents within Staderini's nucleus intercalatus of the rabbit medulla, unitary and/or multiunitary activity was recorded during systematic micro-electrode penetrations performed in said nucleus and in adjoining structures, i.e., the motor nuclei of X and XII cranial nerves, the nuclei gigantocellularis and ventralis of the reticular formation, and (for reference) the nucleus of solitary tract. Each one of the 198 explored foci was tested for reactivity to the chemical stimulation of lingual taste buds (papillae circumvallatae and foliatae, IX nerve). For all structures, the density of the response was noted, as well as their latency and strength. Each structure explored was seen to react to gustatory stimuli. Reactivity of nucleus intercalatus, however, proved to be very similar to that of n. tracti solitarii, and far greater than that of the vagal or hypoglossal motor nuclei and that of the reticular formation. The hypothesis th at the gustatory activation of nucleus intercalatus might be nothing but aspecific side-activation of convergence neurons reticular in nature seems therefore to be disproved.
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