Marder E, Eisen J S
J Neurophysiol. 1984 Jun;51(6):1362-74. doi: 10.1152/jn.1984.51.6.1362.
The two pyloric dilator (PD) motor neurons and the single anterior burster (AB) interneuron are electrically coupled and together comprise the pacemaker for the pyloric central pattern generator of the stomatogastric ganglion of the lobster, Panulirus interruptus. Previous work (31) has shown that the AB neuron is an endogenously bursting neuron, while the PD neuron is a conditional burster. In this paper the effects of physiological inputs and neurotransmitters on isolated PD neurons and AB neurons were studied using the lucifer yellow photoinactivation technique (33). Stimulation of the inferior ventricular nerve (IVN) fibers at high frequencies elicits a triphasic response in AB and PD neurons: a rapid excitatory postsynaptic potential (EPSP) followed by a slow inhibitory postsynaptic potential (IPSP), followed by an enhancement of the pacemaker slow-wave depolarizations. Photoinactivation experiments indicate that the enhancement of the slow wave is due primarily to actions of the IVN fibers on the PD neurons but not on the AB neuron. Bath-applied dopamine dramatically alters the motor output of the pyloric system. Photoinactivation experiments show that 10(-4) M dopamine increases the amplitude and frequency of the slow-wave depolarizations recorded in the AB neurons but hyperpolarizes and inhibits the PD neurons. Bath-applied serotonin increases the frequency and amplitude of the slow-wave depolarizations in the AB neuron but has no effect on PD neurons. Pilocarpine, a muscarinic cholinergic agonist, stimulates slow-wave depolarization production in both PD neurons and the AB neuron, but the waveform and frequency of the slow waves elicited are quite different. These results show that although the electrically coupled PD and AB neurons always depolarize synchronously and act together as the pacemaker for the pyloric system, they respond differently to a neuronal input and to several putative neuromodulators. Thus, despite electrical coupling sufficient to ensure synchronous activity, the PD and AB neurons can be modulated independently.
两个幽门扩张肌（PD）运动神经元和单个前爆发神经元（AB）中间神经元存在电耦合，它们共同构成了龙虾（Panulirus interruptus）口胃神经节幽门中央模式发生器的起搏器。先前的研究（31）表明，AB神经元是内源性爆发神经元，而PD神经元是条件性爆发神经元。在本文中，我们使用荧光黄光灭活技术（33）研究了生理输入和神经递质对分离的PD神经元和AB神经元的影响。高频刺激心室下神经（IVN）纤维会在AB和PD神经元中引发三相反应：快速兴奋性突触后电位（EPSP），随后是缓慢抑制性突触后电位（IPSP），接着是起搏器慢波去极化增强。光灭活实验表明，慢波增强主要是由于IVN纤维对PD神经元的作用，而非对AB神经元的作用。浴加多巴胺会显著改变幽门系统的运动输出。光灭活实验表明，10^(-4) M多巴胺会增加AB神经元中记录的慢波去极化的幅度和频率，但会使PD神经元超极化并抑制其活动。浴加5-羟色胺会增加AB神经元中慢波去极化的频率和幅度，但对PD神经元没有影响。毛果芸香碱，一种毒蕈碱型胆碱能激动剂，会刺激PD神经元和AB神经元产生慢波去极化，但引发的慢波波形和频率有很大不同。这些结果表明，尽管电耦合的PD和AB神经元总是同步去极化，并共同作为幽门系统的起搏器，但它们对神经元输入和几种假定的神经调质的反应不同。因此，尽管电耦合足以确保同步活动，但PD和AB神经元仍可独立调节。
