Pearson K G, Reye D N, Parsons D W, Bicker G
J Neurophysiol. 1985 Apr;53(4):910-25. doi: 10.1152/jn.1985.53.4.910.
We have used intracellular recording and staining techniques to investigate the cellular mechanisms for the initiation and maintenance of flight in the locust, Locusta migratoria. In particular, we examined the properties of a small group of interneurons in the mesothoracic ganglion. We refer to these interneurons as 404 neurons. Their structure has been described, in a closely related species, by Watson and Burrows (21). Using a preparation in which intracellular recordings could be made from the main neurite of a 404 neuron during the generation of flight activity, we observed that the 404 neurons discharged tonically throughout flight episodes elicited by a constant wind stimulus on the head and by a sudden dimming of the lights. Their discharge rate was linearly related to the frequency of the flight activity. Depolarization of individual 404 neurons often initiated flight activity in quiescent preparations, and the application of hyperpolarizing currents during a flight episode either slowed or stopped flight activity. Hyperpolarizing currents also prevented the initiation of flight activity in some preparations. Individual 404 neurons were not always necessary for the generation of flight activity, since flight activity sometimes persisted when all spiking in a 404 neuron was prevented by the application of a hyperpolarizing current. We conclude that the 404 neurons function to initiate and maintain flight activity in response to wind stimulation of the head, but we have not yet established that they are the only thoracic neurons with this function. The 404 neurons discharged with a high-frequency burst at the time of triggering of a kick. Since the motor program for a jump is similar to that for a kick, the 404 neurons may also be involved in linking the initiation of flight activity to the jump. None of our data indicate that the 404 neurons receive input from the central rhythm generator. Thus the neuronal circuitry for flight appears to be hierarchically organized with at least one distinct neuronal system providing a tonic drive to initiate and maintain activity in the system that patterns activity in flight motoneurons.
我们运用细胞内记录和染色技术，研究了飞蝗（Locusta migratoria）飞行启动与维持的细胞机制。具体而言，我们检测了中胸神经节中一小群中间神经元的特性。我们将这些中间神经元称为404神经元。Watson和Burrows（21）在一个亲缘关系相近的物种中描述了它们的结构。利用一种能在飞行活动产生期间从404神经元的主要神经突进行细胞内记录的标本，我们观察到，在头部受到恒定风刺激和灯光突然变暗引发的整个飞行过程中，404神经元持续放电。它们的放电频率与飞行活动的频率呈线性相关。单个404神经元的去极化常常在静止标本中引发飞行活动，并且在飞行过程中施加超极化电流会使飞行活动减慢或停止。超极化电流在某些标本中也能阻止飞行活动的启动。单个404神经元对于飞行活动的产生并非总是必需的，因为当通过施加超极化电流阻止404神经元的所有动作电位发放时，飞行活动有时仍会持续。我们得出结论，404神经元的功能是响应头部的风刺激来启动和维持飞行活动，但我们尚未确定它们是唯一具有此功能的胸段神经元。在踢腿触发时，404神经元会高频爆发式放电。由于跳跃的运动程序与踢腿相似，404神经元可能也参与将飞行活动的启动与跳跃联系起来。我们的数据均未表明404神经元接收来自中枢节律发生器的输入。因此，飞行的神经回路似乎是分层组织的，至少有一个独特的神经元系统提供紧张性驱动，以启动和维持使飞行运动神经元活动模式化的系统中的活动。
