Jansen R F, Pieneman A W, Maat A T
Faculty of Biology, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands.
J Neurophysiol. 1999 Dec;82(6):3378-91. doi: 10.1152/jn.1999.82.6.3378.
Central pattern generators (CPGs) are neuronal circuits that drive active repeated movements such as walking or swimming. Although CPGs are, by definition, active in isolated central nervous systems, sensory input is thought play an important role in adjusting the output of the CPGs to meet specific behavioral requirements of intact animals. We investigated, in freely behaving snails (Lymnaea stagnalis), how the buccal CPG is used during two different behaviors, feeding and egg laying. Analysis of the relationship between unit activity recorded from buccal nerves and the movements of the buccal mass showed that electrical activity in laterobuccal/ventrobuccal (LB/VB) nerves was as predicted from in vitro data, but electrical activity in the posterior jugalis nerve was not. Autodensity and interval histograms showed that during feeding the CPG produces a much stronger rhythm than during egg laying. The phase relationship between electrical activity and buccal movement changed little between the two behaviors. Fitting the spike trains recorded during the two behaviors with a simple model revealed differences in the patterns of electrical activity produced by the buccal system during the two behaviors investigated. During egg laying the bursts contained less spikes, and the number of spikes per burst was significantly more variable than during feeding. The time between two bursts of in a spike train was longer during egg laying than during feeding. The data show what the qualitative and quantitative differences are between two motor patterns produced by the buccal system of freely behaving Lymnaea stagnalis.
中枢模式发生器（CPGs）是驱动诸如行走或游泳等主动重复运动的神经回路。虽然根据定义，CPGs在孤立的中枢神经系统中是活跃的，但感觉输入被认为在调整CPGs的输出以满足完整动物的特定行为需求方面发挥着重要作用。我们在自由活动的蜗牛（椎实螺）中研究了在两种不同行为，即进食和产卵过程中，颊部CPG是如何被使用的。对从颊神经记录的单位活动与颊部团块运动之间关系的分析表明，颊外侧/腹侧（LB/VB）神经中的电活动与体外数据预测的一致，但后颈神经中的电活动并非如此。自动密度直方图和间隔直方图显示，在进食过程中CPG产生的节律比产卵时要强得多。两种行为之间，电活动与颊部运动的相位关系变化不大。用一个简单模型拟合两种行为期间记录的脉冲序列，揭示了在所研究的两种行为期间颊部系统产生的电活动模式的差异。在产卵过程中，脉冲串包含的尖峰较少，并且每个脉冲串的尖峰数量比进食时的变化明显更大。在产卵过程中，脉冲序列中两个脉冲串之间的时间比进食时更长。数据显示了自由活动的椎实螺颊部系统产生的两种运动模式之间的定性和定量差异。
