家鸽Herbst小体对振动的反应特征

鸟类的Herbst小体是一种形态特殊的感觉性神经末梢器官.本文利用电生理学方法,研究了家鸽腿部胫骨-腓骨之间的Herbst小体对振动刺激的反应特征.这种小体对振动刺激非常敏感,当振动频率在600—800赫时,它们有反应的最低阈值约为0.3微米.不同的Herbst小体的反应阈值与频率的关系曲线表明:这种小体具有明显的带通滤波的特征,对振动反应的最佳频率范围为400—1000赫.在适宜频率、超阈值强度的振动刺激下,Herbst小体能以1:1的方式作出反应,即相对于每次正弦波振动刺激都有一个锁相的神经脉冲产生.在背根脊神经节内的细胞外记录表明:对振动敏感的神经节细胞具有和Herbst小体完全相似的反应特征.

Responses of the Herbst Corpuscles in the Pigeon to Vibration

The avian Herbst corpuscle is one kind of morphologically specialized sensory end-organs. By means of the electrophysiological recording from single Herbst corpuscles located in the interosseous region of the pigeon's leg, response characteristics of such a kind of corpuscles to vibration have been studied. The Herbst corpuscle is very sensitive to vibrational stimuli, which were transmitted by an aluminium stylus (0.2 mm, diameter of its tip) to single Herbst corpuscle on the tibia or to the bone at the ankle joint.The lowest threshold amplitude (peak to peak)for the Herbst corpuscle is about 0.3 A*m at the best frequency of 600 -800 Hz.The threshold-frequency relationships for the individual Herbst corpuscles show that the Herbst corpuscles possess "bandpass-filter" property like the mammalian Pacinian corpuscles.Their best frequencies cover a frequency range of 400- 1000 Hz.When supra-threshold vibrational stimuli of adequate frequencies were applied, the Herbst corpuscle could fire in a regular one-to-one fashion, namely,one phase-locked spike per sine wave.The extracellular recordings from the dorsal spinal ganglion cells of the lumbosacral spinal cord show that the vibration-sensitive units have the properties quite similar to those of the Ilerbsl corpuscle.The vibration sense mediated by the Herbst corpuscle in the leg may play an important warning role for a sleeping bird on a branch or the ground in sensing approaching predators.