Nargeot R, Baxter D A, Byrne J H
Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas 77030, USA.
J Neurosci. 1997 Nov 1;17(21):8093-105. doi: 10.1523/JNEUROSCI.17-21-08093.1997.
Operant conditioning is characterized by the contingent reinforcement of a designated behavior. Previously, feeding behavior in Aplysia has been demonstrated to be modified by operant conditioning, and a neural pathway (esophageal nerve; E n.) that mediates some aspects of reinforcement has been identified. As a first step toward a cellular analysis of operant conditioning, we developed an in vitro buccal ganglia preparation that expressed the essential features of operant conditioning. Motor patterns that represented at least two different aspects of fictive feeding (i.e., ingestion-like and rejection-like motor patterns) were elicited by tonic stimulation of a peripheral buccal nerve (n.2,3). Three groups of preparations were examined. In a contingent-reinforcement group, stimulation of E n. was contingent on the expression of a specific type of motor pattern (i.e., either ingestion-like or rejection-like). In a yoke-control group, stimulation of E n. was not contingent on any specific pattern. In a control group, E n. was not stimulated. The frequency of the reinforced pattern increased significantly only in the contingent-reinforcement group. No changes were observed in nonreinforced patterns or in the motor patterns of the control and yoke-control groups. Contingent reinforcement of the ingestion-like pattern was associated with an enhancement of activity in motor neuron B8, and this enhancement was specific to the reinforced pattern. These results suggest that the isolated buccal ganglia expressed an essential feature of operant conditioning (i.e., contingent reinforcement modified a designated operant) and that this analog of operant conditioning is accessible to cellular analysis.
操作性条件反射的特点是对特定行为进行偶联强化。此前，已证明海兔的进食行为可通过操作性条件反射进行改变，并且已确定一条介导强化某些方面的神经通路（食管神经；E n.）。作为对操作性条件反射进行细胞分析的第一步，我们开发了一种体外颊神经节标本，该标本表现出操作性条件反射的基本特征。通过对一条外周颊神经（n.2,3）进行强直刺激，引发了代表拟进食至少两个不同方面的运动模式（即类似摄食和类似拒食的运动模式）。对三组标本进行了检查。在偶联强化组中，对E n.的刺激取决于特定类型运动模式的表达（即类似摄食或类似拒食）。在配对对照组中，对E n.的刺激不取决于任何特定模式。在对照组中，不刺激E n.。仅在偶联强化组中，强化模式的频率显著增加。在未强化模式或对照组和配对对照组的运动模式中未观察到变化。类似摄食模式的偶联强化与运动神经元B8的活动增强相关，并且这种增强特定于强化模式。这些结果表明，分离的颊神经节表现出操作性条件反射的一个基本特征（即偶联强化改变了特定的操作性行为），并且这种操作性条件反射的类似物可用于细胞分析。
