Trimarchi J R, Schneiderman A M
Section of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853-2702.
J Exp Biol. 1993 Apr;177:149-67. doi: 10.1242/jeb.177.1.149.
Cinematographic analysis reveals that an important component of the light-elicited escape response of Drosophila melanogaster is the extension of the femur-tibia joint of the mesothoracic leg. During the jumping phase of the response, this extension works synergistically with extension of the femur. Femur extension is generated by contraction of the tergotrochanteral muscle (TTM), one of four previously described escape response muscles. Femur-tibia joint extension in the mesothoracic leg has been thought to be controlled by contraction of the tibial levator (TLM), an intrinsic leg muscle. We investigated the activation of the TLM during the escape response. Electrical stimulation of the giant fiber interneuron that mediates the escape response results in activation of the TLM with a latency of 1.46 +/- 0.02 ms. The TLM is innervated by a motor neuron (TLMn) with a large cell body in the mesothoracic ganglion. The TLMn has extensive arborizations in the lateral mesothoracic leg neuromere and has a prominent medially directed neurite. To investigate possible presynaptic inputs activating the TLMn during the escape response, we analyzed the muscle responses of two mutants, giant fiber A1 and bendless. Our analysis suggests that the TLMn is activated by a novel pathway.
电影摄影分析显示，果蝇光诱发逃避反应的一个重要组成部分是中胸腿股骨-胫骨关节的伸展。在反应的跳跃阶段，这种伸展与股骨的伸展协同作用。股骨伸展是由背转子肌（TTM）收缩产生的，TTM是先前描述的四种逃避反应肌肉之一。中胸腿的股骨-胫骨关节伸展一直被认为是由腿部固有肌肉胫骨提肌（TLM）的收缩控制的。我们研究了逃避反应期间TLM的激活情况。电刺激介导逃避反应的巨纤维中间神经元会导致TLM激活，潜伏期为1.46±0.02毫秒。TLM由中胸神经节中一个大细胞体的运动神经元（TLMn）支配。TLMn在中胸腿外侧神经节有广泛的分支，并有一条明显的向内侧延伸的神经突。为了研究逃避反应期间激活TLMn的可能突触前输入，我们分析了两个突变体巨纤维A1和无弯曲的肌肉反应。我们的分析表明，TLMn是由一条新途径激活的。
