Staras K, Kemenes G, Benjamin P R
Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Falmer, Brighton, United Kingdom BN1 9QG.
J Neurosci. 1999 Jan 1;19(1):347-57. doi: 10.1523/JNEUROSCI.19-01-00347.1999.
We used a behavioral learning paradigm followed by electrophysiological analysis to find sites in the Lymnaea feeding network in which electrical changes could be recorded after appetitive conditioning. Specifically, we analyzed conditioning-induced changes in cellular responses in the mechanosensory conditioned stimulus (CS) pathway, in the central pattern generator (CPG) network, and in feeding motoneurons. During training, experimental animals received 15 pairings of lip touch (the CS) with sucrose (the unconditioned stimulus, US). Control animals received 15 random CS and US presentations. Electrophysiological tests on semi-intact preparations made from conditioned animals demonstrated a network correlate of the overall feeding conditioned response, a touch-evoked CPG-driven fictive feeding rhythm. At the motoneuronal level, we found significant conditioning-induced increases in the amplitude of an early touch-evoked EPSP and spike activity, recorded from the B3 feeding motoneuron. Increases in EPSP amplitude and motoneuronal spike activity could occur independently of conditioned fictive feeding. These changes in response recorded at the level of CPG interneurons, and motoneurons were preceded by changes recorded in the CS pathway. This was demonstrated by recording a conditioning-induced increase in the number of touch-evoked spikes in the cerebrobuccal connective, which forms part of the CS pathway. The finding that electrophysiological changes after conditioning can be recorded at multiple sites in this simple system provided an important intermediate level of analysis between whole animal behavior and cellular studies on the synaptic sites of plasticity.
我们采用行为学习范式并结合电生理分析，来寻找椎实螺进食网络中在食欲性条件反射后可记录到电变化的位点。具体而言，我们分析了条件反射诱导的机械感觉条件刺激（CS）通路、中枢模式发生器（CPG）网络以及进食运动神经元中细胞反应的变化。在训练过程中，实验动物接受了15次唇部触碰（CS）与蔗糖（非条件刺激，US）的配对。对照动物接受了15次CS和US的随机呈现。对由条件反射动物制备的半完整标本进行的电生理测试表明，存在与整体进食条件反应相关的网络关联，即一种触觉诱发的由CPG驱动的虚构进食节律。在运动神经元水平，我们发现从B3进食运动神经元记录到，条件反射显著诱导早期触觉诱发的兴奋性突触后电位（EPSP）和动作电位活动的幅度增加。EPSP幅度和运动神经元动作电位活动的增加可能独立于条件性虚构进食而发生。在CPG中间神经元和运动神经元水平记录到的这些反应变化之前，CS通路中已记录到变化。这通过记录在构成CS通路一部分的脑颊连接中条件反射诱导的触觉诱发动作电位数量增加得以证明。在这个简单系统中，条件反射后可在多个位点记录到电生理变化这一发现，为全动物行为和可塑性突触位点的细胞研究之间提供了一个重要的中间分析层面。
