Garm A, Bielecki J
Department of Cell and Organism Biology, Lund University, Lund, Sweden.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2008 Jul;194(7):641-51. doi: 10.1007/s00359-008-0336-0. Epub 2008 Apr 30.
A major part of the cubozoan central nervous system is situated in the eye-bearing rhopalia. One of the neuronal output channels from the rhopalia carries a swim pacemaker signal, which has a one-to-one relation with the swim contractions of the bell shaped body. Given the advanced visual system of box jellyfish and that the pacemaker signal originates in the vicinity of these eyes, it seems logical to assume that the pacemakers are modified by the visual input. Here, the firing frequency and distribution of inter-signal intervals (ISIs) of single pacemakers are examined in the Caribbean box jellyfish, Tripedalia cystophora. It is shown that the absolute ambient light intensity, if kept constant, has no influence on the signal, but if the intensity changes, it has a major impact on both frequency and ISIs. If the intensity suddenly drops there is an increase in firing frequency, and the ISIs become more homogeneously distributed. A rise in intensity, on the other hand, produces a steep decline in the frequency and makes the ISIs highly variable. These electrophysiological data are correlated with behavioral observations from the natural habitat of the medusae.
立方水母纲动物中枢神经系统的主要部分位于带有眼睛的缘膜瓣中。来自缘膜瓣的神经元输出通道之一携带游泳起搏器信号，该信号与钟形身体的游泳收缩具有一一对应的关系。鉴于箱形水母具有先进的视觉系统，且起搏器信号起源于这些眼睛附近，因此可以合理推测起搏器会受到视觉输入的影响。在此，对加勒比箱形水母（Tripedalia cystophora）单个起搏器的放电频率和信号间间隔（ISI）分布进行了研究。结果表明，如果绝对环境光强度保持恒定，则对信号没有影响，但如果强度发生变化，则会对频率和ISI产生重大影响。如果强度突然下降，放电频率会增加，ISI分布会变得更加均匀。另一方面，强度增加会导致频率急剧下降，并使ISI高度可变。这些电生理数据与来自水母自然栖息地的行为观察结果相关联。
