NEURAL ACTIVITY OF CHORDA TYMPANI MECHANOSENSITIVE FIBERS DURING LICKING BEHAVIOR IN RATS
NEURAL ACTIVITY OF CHORDA TYMPANI MECHANOSENSITIVE FIBERS DURING LICKING BEHAVIOR IN RATS
复制标题
DOI：
10.1016/0006-8993(95)00582-b
复制
发表时间：
1995-08-21
期刊：
影响因子：
2.9
通讯作者：
MORIMOTO, T
中科院分区：
文献类型：
--
作者：
MATSUO, R;INOUE, T;MORIMOTO, T
供应舌前三分之二的鼓索神经含有味觉和机械敏感型传入纤维。我们分析了大鼠在舔食行为中记录到的各种神经纤维的放电模式，其中4种是味觉敏感型，12种是机械敏感型。在麻醉状态下对这两种类型的发生率进行电生理评估，并测量它们的传导速度。在自由活动动物中的记录显示，支配舌背的机械敏感纤维每舔一次发出两次突发性放电，这表明舌头与上门牙和/或嘴唇的接触发生在舌头前伸和后缩的过程中。来自舌尖的纤维每舔一次就会出现一次突发性放电，这是对接触饮水口的反应。在舌外侧纤维或味觉敏感纤维中，没有观察到与舔咬信号同步的节律性放电。这种机械感受器放电在整个鼓索神经的记录中很难检测到。这种反应的掩蔽主要是由于舔舔诱导的机械刺激激活了少量的机械敏感纤维。唾液的润滑作用也降低了机械感受器的敏感性。尽管机械敏感纤维的数量很少，但与味觉敏感纤维相比，机械敏感纤维的轴突具有更快的传导速度(直径更大)。这可能是为什么在清醒的大鼠中，被解剖的神经束更多地表现出机械反应而不是味觉反应的原因。
The chorda tympani nerve, supplying the anterior two-thirds of the tongue, contains gustatory and mechanosensitive afferent fibers. We have analyzed discharge patterns in rats of various fibers recorded from dissected nerve filaments during licking behavior of which 4 were taste-sensitive and 12 mechanosensitive. The incidence of these two types was estimated electrophysiologically under anesthesia and their conduction velocity measured. Recordings in freely moving animals showed that the mechanosensitive fibers innervating the dorsal part of the tongue gave two burst discharges per lick, suggesting that contact of the tongue with the upper incisors and/or lip occurred during tongue protrusion and retraction. The fibers from the tip of the tongue showed one burst discharge per lick, which was the response to contact with a drinking spout. No rhythmical discharges synchronized with lick signals were observed in the fibers from the lateral part of the tongue or the taste-sensitive fibers. Such mechanoreceptor discharges were difficult to detect in recordings from the whole chorda tympani nerve. This masking of responses was due mainly to activation of a small number of mechanosensitive fibers by licking-induced mechanical stimulation. The lubricating action of saliva also decreased mechanoreceptor sensitivity. Despite their small number, the mechanosensitive fibers had axons with faster conduction velocities (larger diameter) than the taste-sensitive fibers. This was probably the reason why dissected nerve bundles more frequently showed mechanical than taste responses in conscious rats.