A: Diagrammatic illustration of the system stimulating the oropharynx by electric pulses (stimulation electrode), and by test solutions (infusion syringe pump) in humans. Both stimulus apparatus tube were introduced into the pharyngeal region through the nasal cavity, and placed on the posterior wall of the oropharynx. See text for details. B: Enlarged picture of the electrode tip (filled arrow) connected to a flexible stainlesssteel coil spring tube for electrical stimulation and tip of the polyethylene tube for stimulation by solution (open arrow). C: Position of the electrode on the posterior wall of the oropharynx and the area stimulated by a test solution. The electrode is indicated by dashed line, and the area after application of a test solution (0.1 ml) is stained blue with food coloring.

Figure 1: The experimental setup.