Eisen J S, Marder E
J Neurophysiol. 1984 Jun;51(6):1375-93. doi: 10.1152/jn.1984.51.6.1375.
During motor activity of the pyloric system of the lobster stomatogastric ganglion, there are rhythmic alternations between activity in the pyloric dilator (PD) and pyloric (PY) motor neurons. We studied the phase relations between PD motor neuron activity and PY motor neuron activity in preparations cycling at a wide range of frequencies and after altering the activity of the PD neurons. The PY neurons fall into two classes, early (PE) and late (PL) (21), distinguished by the different phases in the pyloric cycle at which they fire. The phase at which PE neurons fired and the phase at which PL neurons fired was independent of pyloric cycle frequency over a range of frequencies from 0.5 to 2.25 Hz. The anterior burster (AB) interneuron is electrically coupled to the PD motor neurons. Together the AB and PD neurons form the pacemaker for the pyloric system. Synchronous depolarization of the AB and PD neurons evokes a complex inhibitory post-synaptic potential (IPSP) in PY neurons. This IPSP has two components: an early, AB neuron-derived component and a late, PD neuron-derived component. Deletion of the PD neurons from the pyloric circuit by photoinactivation removed the PD-evoked component of the pacemaker-evoked IPSP. This resulted in a decrease in the duration of the IPSP evoked by pacemaker depolarization and a significant advance in the firing phase of PY neurons. Bath application of dopamine was used to hyperpolarize and inhibit the PD neurons (30), causing them to release less neurotransmitter. As a consequence, the duration of the IPSP evoked by pacemaker depolarization was decreased and the firing phase of the PY neurons was significantly advanced. Stimulation of the inferior ventricular nerve (IVN) produces a slow excitation of the PD neurons (30), causing them to release more neurotransmitter. Consequently, the duration of the IPSP evoked by pacemaker depolarization was increased and the firing phase of the PY neurons was significantly retarded for several cycles of pyloric activity following IVN stimulation. Thus, modulation of the strength of PD-evoked inhibition in PY neurons is responsible for altering the firing phase of the PY neurons with respect to the pyloric pacemaker. We suggest that frequency of the pyloric output and the phase relations of the elements within the pyloric cycle can be regulated independently. The potential implications of these data for modulation of synaptic efficacy in other preparations are discussed.
在龙虾口胃神经节幽门系统的运动活动期间，幽门扩张肌（PD）和幽门（PY）运动神经元的活动存在节律性交替。我们研究了在广泛频率范围内循环的标本中以及改变PD神经元的活动后，PD运动神经元活动与PY运动神经元活动之间的相位关系。PY神经元分为两类，早期（PE）和晚期（PL）（21），通过它们放电的幽门周期中的不同相位来区分。在0.5至2.25Hz的频率范围内，PE神经元放电的相位和PL神经元放电的相位与幽门周期频率无关。前爆发神经元（AB）中间神经元与PD运动神经元电耦合。AB和PD神经元共同构成幽门系统的起搏器。AB和PD神经元的同步去极化在PY神经元中诱发复杂的抑制性突触后电位（IPSP）。该IPSP有两个成分：一个早期的、源自AB神经元的成分和一个晚期的、源自PD神经元的成分。通过光灭活从幽门回路中删除PD神经元，消除了起搏器诱发的IPSP中PD诱发的成分。这导致起搏器去极化诱发的IPSP持续时间缩短，并且PY神经元的放电相位显著提前。浴用多巴胺用于使PD神经元超极化并抑制它们（30），导致它们释放更少的神经递质。结果，起搏器去极化诱发的IPSP持续时间缩短，并且PY神经元的放电相位显著提前。刺激下室神经（IVN）会使PD神经元产生缓慢兴奋（30），导致它们释放更多的神经递质。因此，起搏器去极化诱发的IPSP持续时间增加，并且在IVN刺激后的几个幽门活动周期中，PY神经元的放电相位显著延迟。因此，PY神经元中PD诱发抑制强度的调节负责改变PY神经元相对于幽门起搏器的放电相位。我们认为幽门输出频率和幽门周期内各元素的相位关系可以独立调节。讨论了这些数据对其他标本中突触效能调节的潜在影响。
