Figure 1. Effect of 5-HT on trigeminal rhythmic activities. (A) After a coronal transection at the Y-crossing point, BIC (10 µM) - NMA (20 µM) application induced trigeminal rhythmic activities. (B) Rhythmic trigeminal motor activity was not induced in the whole brainstem preparations by chemical application of BIC (10 µM) - NMA (20 µM), whereas it was by an application of BIC (10 µM) - NMA (20 µM) combined with 5-HT (60 µM). (C) Comparison of the effect of 5-HT (60 µM) - NMA (20 µM) - BIC (10 µM) on trigeminal activities (Vm) with that on cervical nerve (C2) activities (n = 5). Middle traces show Vm and C2 activities after application. These activities were not synchronized with each other. Upper traces: trigeminal activities (Vm). Lower traces: cervical nerve (C2) activities.