||Modulation of excitability of trigeminal neurons during electrical stimulation of the superior laryngeal nerve in anesthetized rabbits
学位の種類: 博士（歯学）. 報告番号: 甲第4153号. 学位記番号: 新大院博（歯）甲第351号. 学位授与年月日: 平成28年3月23日
The present study investigated the effect of electrical stimulation of the superior laryngeal nerve (SLN) on evoked potentials from trigeminal interneurons. Experiments were carried out on 19 rabbits anesthetized with urethane. Single-unit responses evoked by electrical stimulation of the inferior alveolar nerve were recorded in the trigeminal nucleus. To evoke swallowing reflex, the SLN was electrically stimulated (train pulses; 0.2 ms, 30 Hz). Current intensity of SLN stimulation was set at 2, 4, or 8 times the threshold for evoking swallowing reflex at least once for 10 s. Initiation and change in latency were compared among the periods (before, during, and after SLN stimulation) or among stimulus intensities. Inhibition of evoked responses and delay in latency was observed in 15 of 27 identified neurons (55.6%) and 26/27 (96.3%) neurons, respectively, either during or after SLN stimulation. The rate of inhibition of evoked responses was significantly different among SLN stimulus intensities. Modulated neurons were divided into two groups based on latency, short (< 3 ms) or long (>= 3 ms). Longer latencies resulted in longer delays. Eighteen neurons (66.7%) were found to project to the digastric motor nucleus. Most neurons were distributed in the main sensory trigeminal nucleus or subnucleus-γ of the oral nucleus of the spinal trigeminal tract. These results suggest that sensory information originating from the orofacial region, possibly related to the jaw reflex, was inhibited during or after SLN stimulation possibly by input from the swallowing central pattern generator.