Katz P S, Harris-Warrick R M
Section of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853.
J Neurosci. 1990 May;10(5):1495-512. doi: 10.1523/JNEUROSCI.10-05-01495.1990.
In the stomatogastric nervous system of the crab, Cancer borealis, a set of 4 serotonergic/cholinergic proprioceptive neurons, called gastropyloric receptor (GPR) cells, have effects on the pyloric motor pattern. In a semi-intact foregut preparation, the GPR cells are not activated by movements of the pyloric filter; instead they respond to the slower movements of the gastric mill (Katz et al., 1989). Thus, their activity is not synchronized to the pyloric motor pattern. However, when the GPR cells are stimulated in an in vitro preparation in a manner that resembles their normal firing pattern, they produce dramatic effects on the pyloric motor pattern. These effects include: (1) a prolonged increase in the pyloric cycle frequency, (2) a momentary pause in the motor pattern, (3) transient inhibition of some motor neurons, (4) strong excitation of other motor neurons, and (5) altered phase relationships of the different components of the motor pattern. These changes in the motor pattern are due to direct effects of the GPR cells on neurons in the pyloric central pattern generator (CPG). All of the cells in the pyloric circuit appear to receive GPR input. However, only 2 neurons receive detectable rapid nicotinic synaptic potentials. The other neurons receive only slower neuromodulatory input from GPR stimulation. The neuromodulatory effects include burst enhancement, plateau potential enhancement, excitation, and inhibition. These modulatory effects are largely mimicked by bath-applied serotonin (5-HT). Thus, primary sensory neurons can alter the production of motor patterns by a CPG through a phase-independent mechanism; these proprioceptors do not need to fire at a precise time in the cycle to be effective because their effects are mediated through the slower actions of the neuromodulator 5-HT.
在北方黄道蟹的口胃神经系统中，有一组4个血清素能/胆碱能本体感受神经元，称为幽门胃受体（GPR）细胞，它们对幽门运动模式有影响。在半完整前肠标本中，幽门滤器的运动不会激活GPR细胞；相反，它们对胃磨的较慢运动有反应（Katz等人，1989年）。因此，它们的活动与幽门运动模式不同步。然而，当在体外标本中以类似于其正常放电模式的方式刺激GPR细胞时，它们会对幽门运动模式产生显著影响。这些影响包括：（1）幽门周期频率持续增加，（2）运动模式瞬间暂停，（3）对一些运动神经元的短暂抑制，（4）对其他运动神经元的强烈兴奋，以及（5）运动模式不同组成部分的相位关系改变。运动模式的这些变化是由于GPR细胞对幽门中央模式发生器（CPG）中的神经元的直接作用。幽门回路中的所有细胞似乎都接受GPR输入。然而，只有2个神经元接受可检测到的快速烟碱突触电位。其他神经元仅从GPR刺激中接受较慢的神经调节输入。神经调节作用包括爆发增强、平台电位增强、兴奋和抑制。这些调节作用在很大程度上被浴加血清素（5-HT）模拟。因此，初级感觉神经元可以通过一种与相位无关的机制改变CPG产生的运动模式；这些本体感受器不需要在周期中的精确时间放电就有效，因为它们的作用是通过神经调节剂5-HT的较慢作用介导的。
