Neural correlation between the central and the peripheral neurons in the regulation of the digestive tract in Aplysia

肠神经系统包含大量的外周神经元体，是澳大利亚消化器官所固有的。在去除中枢神经系统的准备中，周围神经元记录了两种节律性爆发活动。其中一种爆发活动持续时间较短，由作物上的神经元、环神经和砂囊同步记录。这种活动被认为引起砂囊的神经源性运动。另一种爆发活动的持续时间更长，并且是由嗉囊和环神经上的神经元同步记录的，但不是在砂囊上。当作物这个暂时储存食物的器官用一个小气球膨胀时，这两种爆炸活动的频率都增加了。这些结果表明，宽感受性外周反射参与了大腹虫消化运动的调节，而长时间爆发活动的功能有待于进一步的研究。砂囊的自主运动包括磨制收缩和混合其内容物的部分收缩。结果表明，收缩是由上述外周神经元的同步爆破活动引起的神经源性收缩，部分收缩是由肌肉组织的起搏器电位引起的肌源性收缩。乙酰胆碱作用于沙囊使外周神经元同步爆破活动频率和肌细胞起搏器电位呈剂量依赖性增加，外周神经元同步爆破活动频率增强。结果表明，砂囊外周神经元和肌肉细胞均具有胆碱能受体，并参与加速砂囊的消化运动。

The enteric nervous system, containing a large number of peripheral neuronal somata, is intrinsic to the digestive organs in Aplysia. Two types of rhythmic bursting activities were recorded from the peripheral neurons in preparations in which the central nervous system had been removed. One of the bursting activities was shorter in duration and was recorded in synchrony from the neurons on the crop, the ring nerve and the gizzard. This activity was suggested to cause the neurogenic movement of the gizzard. The other bursting activity was longer in duration and was recorded synchronously from the neurons on the crop and the ring nerve, but not on the gizzard. When the crop, the organ in which food is temporarily stored, was distended by means of a small balloon, the frequencies of both types of bursting activities were increased. These results suggest that varoceptive peripheral reflexes are involved in the regulation of digestive movements in Aplysia, while the functions of the longer-duration bursting activity should be examined in future studies.The autonomic movements of the gizzard comprise both constrictions for trituration and the partial contractions for mixing its contents. It was shown that the constrictions are the neurogenic contractions originating in the synchronous bursting activities of peripheral neurons as described above and the partial contractions are the myogenic ones generated by the pacemaker potential in the musculature. Acetylcholine applied to the gizzard increased frequencies of both the synchronous bursting activities of the peripheral neurons and the pacemaker potentials in the muscle cells with a dose-dependent manner, while the synchrony among the peripheral bursting neurons was augmented. The results suggest that both the peripheral neurons and muscle cells on the gizzard have cholinergic receptors and are involved in the acceleration of digestive movements of the gizzard.