Mozzachiodi Riccardo, Lechner Hilde A, Baxter Douglas A, Byrne John H
W.M. Keck Center for Neurobiology of Learning and Memory, Department of Neurobiology and Anatomy, The University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Learn Mem. 2003 Nov-Dec;10(6):478-94. doi: 10.1101/lm.65303.
The feeding behavior of Aplysia californica can be classically conditioned using tactile stimulation of the lips as a conditioned stimulus (CS) and food as an unconditioned stimulus (US). Moreover, several neural correlates of classical conditioning have been identified. The present study extended previous work by developing an in vitro analog of classical conditioning and by investigating pairing-specific changes in neuronal and synaptic properties. The preparation consisted of the isolated cerebral and buccal ganglia. Electrical stimulation of a lip nerve (AT4) and a branch of the esophageal nerve (En2) served as the CS and US, respectively. Three protocols were used: paired, unpaired, and US alone. Only the paired protocol produced a significant increase in CS-evoked fictive feeding. At the cellular level, classical conditioning enhanced the magnitude of the CS-evoked synaptic input to pattern-initiating neuron B31/32. In addition, paired training enhanced both the magnitude of the CS-evoked synaptic input and the CS-evoked spike activity in command-like neuron CBI-2. The in vitro analog of classical conditioning reproduced all of the cellular changes that previously were identified following behavioral conditioning and has led to the identification of several new learning-related neural changes. In addition, the pairing-specific enhancement of the CS response in CBI-2 indicates that some aspects of associative plasticity may occur at the level of the cerebral sensory neurons.
加州海兔的摄食行为可以通过将唇部的触觉刺激作为条件刺激（CS），食物作为非条件刺激（US）进行经典条件反射。此外，已经确定了经典条件反射的几种神经关联。本研究通过开发经典条件反射的体外模拟物并研究神经元和突触特性的配对特异性变化，扩展了先前的工作。实验准备包括分离的脑和颊神经节。分别对唇神经（AT4）和食管神经分支（En2）进行电刺激作为CS和US。使用了三种方案：配对、非配对和单独的US。只有配对方案使CS诱发的虚构摄食显著增加。在细胞水平上，经典条件反射增强了CS诱发的向模式启动神经元B31/32的突触输入幅度。此外，配对训练增强了CS诱发的突触输入幅度以及指令样神经元CBI-2中CS诱发的峰电位活动。经典条件反射的体外模拟物重现了先前在行为条件反射后确定的所有细胞变化，并导致了几种新的与学习相关的神经变化的发现。此外，CBI-2中CS反应的配对特异性增强表明，联想可塑性的某些方面可能发生在脑感觉神经元水平。
