Wood E R, Wiel D E, Weeks J C
Institute of Neuroscience, University of Oregon, Eugene 97403-1254, USA.
J Comp Physiol A. 1997 Jun;180(6):639-57. doi: 10.1007/s003590050080.
The larval proleg withdrawal reflex of the hawk moth, Manduca sexta, exhibits robust habituation. This reflex is evoked by deflecting one or more mechanosensory planta hairs on a proleg tip. We examined neural correlates of habituation in an isolated proleg preparation consisting of one proleg and its segmental ganglion. Repeated deflection of a single planta hair caused a significant decrease in the number of action potentials evoked in the proleg motor nerve (which carries the axons of proleg retractor motor neurons). Significant response decrement was seen for interstimulus intervals of 10 s, 60 s and 5 min. Response decrement failed to occur in the absence of repetitive stimulation, the decremented response recovered spontaneously following a rest, and electrical stimulation of a body wall nerve facilitated the decremented response (a neural correlate of dishabituation). Adaptation of sensory neuron responses occurred during repeated hair deflections. However, when adaptation was eliminated by direct electrical stimulation of sensory neurons, the response in the proleg motor nerve still decreased significantly. Muscle recordings indicated that the response of an identified proleg retractor motor neuron decreased significantly during habituation training. Thus, habituation of the proleg withdrawal reflex includes a central component that is apparent at the level of a single motor neuron.
烟草天蛾（Manduca sexta）幼虫的腹足退缩反射表现出强烈的习惯化。该反射是通过轻触腹足尖端的一根或多根机械感觉性腹足毛而诱发的。我们在由一个腹足及其节段神经节组成的离体腹足标本中研究了习惯化的神经关联。对单根腹足毛的重复轻触导致腹足运动神经（携带腹足收缩运动神经元的轴突）诱发的动作电位数量显著减少。在刺激间隔为10秒、60秒和5分钟时，观察到明显的反应递减。在没有重复刺激的情况下，反应递减不会发生，休息后递减的反应会自发恢复，并且对体壁神经的电刺激会促进递减的反应（去习惯化的神经关联）。在重复轻触毛发的过程中，感觉神经元的反应发生了适应性变化。然而，当通过对感觉神经元的直接电刺激消除适应性时，腹足运动神经中的反应仍然显著下降。肌肉记录表明，在习惯化训练期间，一个已识别的腹足收缩运动神经元的反应显著降低。因此，腹足退缩反射的习惯化包括一个在单个运动神经元水平上明显的中枢成分。
