Cortical cells driven by the low-threshold tooth pulpal afferent in cats.

The input pattern and spatial distribution of tooth pulp-driven neurons (TPNs) in the cat cortex were studied by recording the unitary activities of these neurons. Stimulation was applied to the upper and lower canine and molar tooth pulps. It was possible to record activities of TPNs in the deep layers of the areas 3a and 3b of the coronal gyrus of cerebral cortex. TPNs driven by the ipsilateral tooth pulp stimulation were distributed more anteroventrally than those driven by contralateral stimulation. Cells driven by bilateral pulp stimulation were situated between these two neurons. The threshold intensity for TPNs in the area 3a was lower than that for neurons in 3b. The majority of TPNs in the area 3a of the anterior part of the coronal gyrus received inputs from low-threshold masseteric muscular afferents as well as from tooth pulp afferents. The findings suggest that TPNs in the area 3a may have a relation to orofacial motor functions.