Pinsker H M
J Physiol (Paris). 1982;78(8):775-85.
This paper reviews analog and digital studies of the population of siphon motoneurons involved in a defensive withdrawal reflex that is activated by a tactile stimulus to the siphon of Aplysia californica. Multiunit activity was monitored during normal behavior by implanting noninvasive cuff electrodes on the siphon nerve of intact animals. The siphon motoneuron population integrates activity originating in distributed reflex pathways and in a local oscillatory circuit called the Interneuron II (INT II) network, a central pattern generator (CPG) that spontaneously produces large siphon and gill contractions. In intact animals (but not in reduced preparations) a novel tactile stimulus to the siphon phase advances the spontaneously occurring burst of activity in the CPG (on about 60% of trials), thereby transforming the reflex from one that is graded with stimulus intensity to one that is nearly maximal even with weak stimuli. When a series of stimuli are given, reflex decrement (habituation) results, in large part, from a failure to stably entrain the CPG component. When a noxious stimulus is presented across days, long-term sensitization results in large and very prolonged withdrawal responses. The increase in reflex amplitude is due, in part, to heightened entrainment of the CPG (about 90% of trials). Digital spike train analysis revealed an additional factor associated with the prolonged responses of sensitized animals; increased tonic background firing in the motoneuron population that could last for several minutes.
本文回顾了对参与防御性退缩反射的虹吸管运动神经元群体的模拟和数字研究，该反射由对加州海兔虹吸管的触觉刺激激活。在正常行为期间，通过在完整动物的虹吸管神经上植入非侵入性袖带电极来监测多单位活动。虹吸管运动神经元群体整合了源自分布式反射通路和一个称为中间神经元II（INT II）网络的局部振荡电路的活动，INT II网络是一个中央模式发生器（CPG），可自发产生强烈的虹吸管和鳃收缩。在完整动物中（但在简化标本中则不然），对虹吸管的一种新的触觉刺激会使CPG中自发出现的活动爆发提前（约60%的试验中），从而将反射从一种随刺激强度分级的反射转变为即使是弱刺激也几乎最大的反射。当给予一系列刺激时，反射消退（习惯化）很大程度上是由于未能稳定地带动CPG成分。当连续数天给予有害刺激时，长期敏感化会导致大且非常持久的退缩反应。反射幅度的增加部分归因于CPG带动增强（约90%的试验中）。数字尖峰序列分析揭示了与敏感化动物延长反应相关的另一个因素；运动神经元群体中持续性背景放电增加，可持续数分钟。
