Cook D G, Carew T J
Department of Psychology, Yale University, New Haven, Connecticut 06520.
J Neurosci. 1989 Sep;9(9):3107-14. doi: 10.1523/JNEUROSCI.09-09-03107.1989.
Aplysia can readily exhibit operant conditioning of their head-waving response when bright light is used as aversive reinforcement (Cook and Carew, 1986). In the first paper of this series (Cook and Carew, 1989a), we showed that the electromyographic (EMG) activity of a discrete band of neck muscles, the lateral columellar muscles (LCMs) of Aplysia is significantly correlated with the component of head-waving (the horizontal component) that is modified during operant conditioning. In the present paper, we asked whether the EMG activity of the LCMs themselves could also be contingently modified, using the same procedures that produce operant conditioning of the behavioral response. Differential EMG from the LCMs was recorded in freely behaving animals with chronically implanted muscle cuff electrodes. Animals receiving aversive reinforcement (bright light) that was contingent upon specific patterns of LCM activity readily learned to alter their differential EMG output. Like operant conditioning of the head-waving response, this operant modification of LCM activity was rapidly acquired and was specific to the contingencies of reinforcement. These results show that a restricted group of muscles, the LCMs, exhibit the essential features of the head-waving system observed at the behavioral level: (1) their activity is significantly correlated with head-waving behavior, and (2) the LCMs are capable of operant modification of their output. Thus, this restricted response system provides a useful preparation for examining the neural mechanisms of operant conditioning of head-waving in Aplysia.
当强光用作厌恶性强化物时，海兔能够很容易地表现出其头部摆动反应的操作性条件反射（库克和卡鲁，1986年）。在本系列的第一篇论文中（库克和卡鲁，1989a），我们表明，海兔颈部一组离散肌肉（外侧小柱肌，LCMs）的肌电图（EMG）活动与在操作性条件反射过程中发生改变的头部摆动成分（水平成分）显著相关。在本文中，我们探讨了使用产生行为反应操作性条件反射的相同程序，LCMs自身的EMG活动是否也能被偶然改变。用长期植入的肌肉袖带电极在自由活动的动物身上记录LCMs的差异EMG。接受取决于LCM活动特定模式的厌恶性强化（强光）的动物很容易学会改变其差异EMG输出。与头部摆动反应的操作性条件反射一样，LCM活动的这种操作性改变迅速获得，并且特定于强化的偶然性。这些结果表明，一组受限的肌肉，即LCMs，表现出在行为水平观察到的头部摆动系统的基本特征：（1）它们的活动与头部摆动行为显著相关，（2）LCMs能够对其输出进行操作性改变。因此，这个受限的反应系统为研究海兔头部摆动操作性条件反射的神经机制提供了一个有用的实验准备。
